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Chapter 18: Conservation of Materials

Early Neglect of Conservation

Before World War II, conservation of materials was not a major consideration in the design of military equipment in the United States. In fact, extravagance rather than economy was the order of the day. Instead of carefully studying each part of a weapon or vehicle in terms of its military functions, determining the maximum strength or wearing quality required of it, and then manufacturing it of the most readily available material that provided the required strength plus a suitable margin for safety, Ordnance designers tended to specify the highest quality material available thus giving the part strength far in excess of maximum needs. In 1941 a survey of Ordnance items to discover ways of conserving critical materials revealed that, in a multitude of parts not subject to high stresses, alloy steel was prescribed when carbon steel would have been adequate, and that electric-furnace steel was specified for certain purposes even though open-hearth steel would have been just as satisfactory. This prodigality in the use of materials was not confined to the designers of military equipment but was common throughout American industry. Emphasis in military circles on high standards of performance under adverse conditions probably influenced military designers to be more wasteful than their counterparts in private industry, but openhandedness in employing material resources was so common before 1941 that it stood virtually as a national characteristic.1

The most obvious reason for this condition was the wealth of resources found within the United States or under the control of friendly, near-by nations such as Canada and Mexico. With an abundant supply of most essential minerals at hand there was no apparent necessity for parsimony in their use. For the Ordnance Department there were also other reasons for neglecting conservation, among them the national policy that envisaged mobilization in time of war of a comparatively small military force for defense only. To produce the munitions that might be needed by this small force in time of emergency, the resources of the United States, with a few exceptions, were certainly more than adequate. Under such circumstances there was no strong pressure for materials conservation, except for the few items on the War Department list of strategic materials, and even for those the emphasis

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was on building up a reserve stockpile rather than on curtailing their use.2

In some instances, designers in the prewar years chose a critical material for a specific use without giving due consideration to the fact that some other, noncritical, material would have been just as satisfactory. Metallurgical developments in industry were proceeding so rapidly and along so many different lines that it was often impossible for Ordnance designers, who were not themselves metallurgists, to make intelligent choices among materials; and, since conservation of materials was not emphasized, metallurgists and production engineers did not normal].) participate in the process of selecting materials or designs for new items of equipment. Because of the high cost of experimenting and testing, and because of the insistent demand for dependability in weapons, designers generally took a conservative stand, reasoning that it was more economical, at least in the short run, to continue the use of tried and proven materials and manufacturing methods than to experiment with substitutes. “If our designs, as some people have said, were ‘wrapped around a milling machine,’” General Campbell wrote, “it was because we simply could not afford production-engineering studies of our various models or pilots.”3 In some cases substitute materials and mass-production processes that would have saved critical materials, man-hours, and machine-tool time on quantity production were not used before the war because they could not be economically applied to the small-scale production of the peace years. In other cases, critical material needed in only one or two parts of a weapon was also specified for several other parts for the sole purpose of maintaining production of the small quantity actually required each year.4

This is not to say, however, that the Ordnance Department neglected metallurgical research before World War II. For many years, as the Army agency having primary interest in the use of metals, it had carried on intensive metallurgical testing programs at its arsenals and laboratories. As early as 1873 it had established a metallurgical testing laboratory at Watertown Arsenal, and during the years before and after World War I Ordnance pioneered in the development of molybdenum highspeed tool steel, in the use of macroetch-test and radiographic-inspection methods, in welding constructional steels, in determining the effects of cold working and low temperatures on the physical properties of steel, and in studying the causes of season cracking of brass.5 There were laboratories at all the manufacturing arsenals where, within the limitations of the budget, metallurgical research pertaining to Ordnance materials was carried on. But the emphasis was not placed primarily on conservation.

The War Department had carried on continuous studies of sources of strategic and critical materials6 for many years

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preceding the outbreak of World War II, but not until the early months of 1941 did it issue specific instructions on conserving certain widely used metals. On 25 February 1941 the Under Secretary of War wrote to the chiefs of all the supply arms and services calling their attention to the need for conserving zinc, and during the next three months he issued similar memoranda on conserving aluminum, nickel, and tungsten. During this period the Office of Production Management, created in January 1941 and later replaced by the War Production Board, also took an interest in the matter and established a conservation section to promote the adoption by industry and government of measures to conserve scarce materials. Shortly after the President’s declaration of a state of unlimited national emergency on 27 May 1941, the Under Secretary of War established a conservation section within his office headed by an Ordnance officer, Maj. Norris G. Kenny, and issued a directive to all the supply arms and services outlining the War Department conservation policy.7

Principles of the Conservation Program

Long before these steps were taken the Ordnance Department, on its own initiative, had organized a conservation section and had established the basic principles of its conservation program. In October 1940, as the multibillion-dollar defense production program was getting under way, Maj. John H. Frye, an industrial metallurgist in civilian life, was assigned to the staff of General Barnes to promote effective utilization of materials in Ordnance production.8 Major Frye was soon joined by other officers and civilian specialists and during the early months of 1941 this small group initiated studies leading to the revision of many specifications for the purpose of conserving critical material. In February 1942 conservation sections were established in each operating branch of the Industrial Service, with over-all coordination of their efforts centered in Major Frye’s section.9

The Ordnance conservation effort was born of necessity, and was intensely practical in nature. From its beginning in late 1940, the program was geared to the constant fluctuations in the supplies of a wide range of essential materials, and was designed to keep war production going in spite of shortages. When faced with inadequate supplies of various materials needed for the manufacture of munitions, Ordnance adopted the policy of economizing wherever possible to make its limited allocations of critical materials cover all essential requirements. It was recognized that too much devoted to one use would inevitably mean too little available for something else. “We were not saving materials just for the sake of saving them,” Colonel Frye once remarked. “We were saving critical materials on items where they were not needed so we would have enough for other items where these materials were needed.”10

Perhaps the most important principle underlying the Ordnance conservation activities in World War II was that

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substitutions were to be made only after a careful engineering analysis of each affected item of equipment. No attempt was made to introduce sweeping changes without taking into consideration the military functions of each item, and the Ordnance Department resisted efforts by higher headquarters to impose such changes. “It can readily be appreciated,” General Barnes once wrote, “that mandatory edicts or wholesale substitutions are inconsistent with sound engineering design. Most war material was designed in times of plentiful materials. To change these designs now, it is necessary that the service functions and the nature of stresses involved be considered for each part.”11

In this process of studying equipment with an eye to substituting less critical materials, Ordnance engineers were, of course, required to maintain unimpaired the military characteristics of each item. Conservation was not to be practiced at the cost of lowered efficiency, except in cases of dire necessity. The term “downgrading” was sometimes used to describe the substitution process, but it was not a fairly descriptive term. The purpose of the substitution was to eliminate waste caused by improper use of scarce materials; it was not a matter of lowering the quality of any item by making it of inferior material. When, to cite one simple example, the trigger guard of the .30-caliber M1 rifle was changed from chrome-vanadium steel to molybdenum steel, the rifle continued to be just as good as it ever was. Molybdenum steel provided all the strength required in a trigger guard; nothing was to be gained by making the guard any stronger, and critical materials were wasted when chromium and vanadium were used to gain unnecessary added strength.

Another guiding principle of Ordnance conservation activities was cooperation with industry. At virtually every step in the process, industrial specialists contributed to the solution of difficult problems. Hundreds of companies working on Ordnance contracts developed new designs or improved production methods to save labor, machine-tool time, and critical materials. Materials-saving suggestions from contractors and their employees were solicited by the Ordnance Department, particularly in the latter half of 1942, through publication of promotional literature that described the need for conservation and listed specific examples of design changes already adopted to save time and materials.12

In a more orderly manner, the resources of large sections of American industry were put at the disposal of the Ordnance Department through its day-by-day cooperation with trade associations and engineering societies. Through these organizations Ordnance was able to tap the best engineering talent in the country to aid in solving its problems. When, for example, need arose for developing a special kind of steel, members of the American Iron and Steel Institute were called upon for help; when the problem concerned trucks or combat vehicles, the Society of Automotive Engineers came to the rescue; when it concerned plastics, rubber, die-casting, metal-stamping, phenolic finishes, or any other

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major material or industrial process, the appropriate industry association lent aid.

When Ordnance made its first monthly report to the newly formed conservation unit in the Office of the Under Secretary of War in August 1941, only four materials were separately reported on: silk, aluminum, chlorine, and zinc.13 The report stated that Ordnance had taken steps to conserve silk by experimentally replacing it with cotton or rayon in powder bags, to conserve chlorine by changing the bleaching specifications for certain types of paper, and to conserve zinc by using porcelain-coated roofing and siding sheets in place of galvanized sheets and terne (lead-tin alloy) sheets. With aluminum, efforts were being made to substitute other materials wherever possible, and an investigation was under way to determine whether primary aluminum could be saved by manufacturing some items of secondary aluminum by using the die-casting process. In addition to these specific steps, the report declared that Frankford Arsenal had recently issued a hundred-page booklet entitled “Materials Specifications Handbook for Use of Design Engineers of Ordnance Equipment in Selecting Emergency Substitute Materials.”14

Although it did not mention all the conservation activities that were under discussion or in progress at the time, the report clearly indicated that the Ordnance conservation program was just getting under way in August 1941.15 A great deal of uncertainty was still in the air, both as to future production goals and as to the need for drastic conservation measures. Shortages had not yet become acute and the nation was still at peace. Plans for a huge munitions production program had been formulated, but everything was still on a more or less tentative basis.

With the attack on Pearl Harbor the whole situation changed overnight. There was uncertainty for a long time as to the precise requirements of the armed forces and as to national production goals, but everyone knew in December 1941 that war production would soon shift into high gear and that demands for critical materials would reach hitherto unheard-of proportions. The outbreak of war made the need for conservation of materials not only necessary but urgent, particularly for the Ordnance Department and its contractors.

The Ordnance conservation program encompassed an almost infinite variety of materials and manufacturing processes. In January 1940 the Army and Navy Munitions Board approved a list of fourteen strategic materials and fifteen critical materials, nearly all of them used in greater or less degree in the production or storage of munitions.16 But the bulk of the Ordnance conservation effort was concentrated on four materials: alloy steel, copper, aluminum, and rubber. As efforts to conserve each of these materials were made more or less independently, although concurrently, they are here discussed separately.17

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Steel and Its Alloys

During World War II no metal was more widely used by the Ordnance Department than steel. Literally hundreds of items ranging from small bullet cores to large bombs, heavy guns, trucks, and tanks were made primarily of steel. During 1942 and 1943 Ordnance used steel at the rate of more than one million ingot tons a month and took from 50 to 65 percent of all steel allotted to the Army. A conservative estimate of the total quantity of steel used for Ordnance production between 1940 and 1945 is 50 million tons.

Fortunately, the steel industry was one of the largest and most highly developed economic enterprises in the United States at the beginning of World War II and was able to supply the huge quantities needed for war production. In 1940 American companies produced over 65 million ingot tons of steel and productive capacity rose rapidly until by 1944 nearly 90 million ingot tons were produced, more than three times the annual German output. The Ordnance program was never seriously hampered by lack of steel, although occasional difficulties arose from faulty distribution. In 1942–43 sufficient steel was available to permit manufacture of steel cartridge cases when the shortage of brass became acute, the production of steel tank tracks to conserve rubber, and adoption of steel ammunition boxes when other materials proved unsatisfactory. As far as Ordnance was concerned, the pinch came only in certain types of steel for which the demand in war greatly exceeded normal peacetime production. These types possessed qualities of hardness, elasticity, toughness, or ease of fabrication that made them particularly valuable in the manufacture of munitions. Armor plate, for example, had to be hard enough to stop enemy projectiles; armor-piercing ammunition had to be even harder to penetrate enemy armor. The pins that held a tank track together had to have long-wearing qualities, while the steel used in truck cabs and fenders had to be soft and pliable enough to be formed between dies.

Long before World War II, metallurgists had succeeded in producing steels with these characteristics, but only by making liberal use of ferroalloys. After Pearl Harbor, and to some extent even before that date, this practice was threatened by a shortage of both alloys and electric-furnace capacity. At the time that military requirements were skyrocketing, the United States steel industry found itself cut off from most of its foreign sources of tungsten, chromium, vanadium, manganese, and other ferroalloys.18 Even with the more accessible metals such as nickel and molybdenum the demand for a time greatly exceeded the capacity of existing productive facilities. To meet war production schedules under these circumstances, Ordnance and industry introduced a rigid conservation program guided by three fundamental principles: substitution of other materials for alloy steel; improvement of manufacturing processes to reduce waste; and more widespread use of low-alloy steels.

Even with plain carbon steel, which contained no scarce alloys and was relatively abundant, Ordnance engineers

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Chart 10—Percent 
Distribution of steel used, by army agency: 3rd quarter, 1942 and 1943*

Chart 10—Percent Distribution of steel used, by army agency: 3rd quarter, 1942 and 1943*

* Total Army monthly average use in 3rd Quarter of 1943 was 1,834,000 ingot tons; 1942 was 1,930,000 ingot tons.

** Transportation, Quartermaster, and other Army agencies.

Source: Quarterly Review (December 1943). Charts 3-A and 3-B, DRB AGO.

endeavored to avoid waste, using equally satisfactory and more readily available substitutes when they could be found. But finding a suitable substitute was not always a simple matter. It involved careful consideration of many factors such as relative cost, ease of manufacture, and effect on production of conversion to the new material. The most outstanding example of this kind of substitution in Ordnance production during World War II was the use of wood to replace steel in truck and trailer bodies. The substitution of wood for steel in the 2½-ton truck reduced the number of pounds of steel per body from 1,700 to 700; in the 1½-ton truck the reduction was from 1,275 to 600 pounds per body. When multiplied by the thousands of trucks and trailers produced for the Army during the war, the savings were estimated at 75,000 tons in 1942 and more than 350,000 tons in 1943. Initiated by the Motor Transport Service of the Quartermaster Corps early in the war period, this project was continued after the MTS was transferred to Ordnance in August 1942 and proved to be the second largest source of steel conservation in the Ordnance production program.19

The measure adopted by Ordnance which ranked first as a steel-saver was not a matter of substitution or change in design but a refinement in the manufacturing process. Next to tanks and trucks, Ordnance used more steel for high-explosive shells than for any other class of items, and achieved its largest saving of steel by

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the simple device of decreasing the weight tolerance of shell forgings as contractors gained experience and improved their forging techniques.20 By observing closer tolerances, industry not only saved thousands of tons of steel in the course of a single year but also saved countless man-hours and machine-hours because the forgings required less machining.21 Similar savings were made in hundreds of other instances. In the Birmingham District, for example, the 155-mm. shell-lifting plug was redesigned as a hollow cup rather than a solid block. The change cut the weight of the plug from about 28 ounces to 10. It saved over 300 tons of steel in the production of one million plugs and at the same time eliminated shrinks from the castings. With the 81-mm, mortar shell, large savings of steel resulted from a combination of a change in design and an improved method of fabrication. Instead of forming the hollow shell by machining from a solid forging, two drawn steel sections were welded together. The result was a saving on 1943 procurement of 6,000 tons of steel and 750,000 machine-hours.22

No matter what steps were taken, however, there was simply no substitute for steel in the great majority of Ordnance items. Scattered marginal savings were possible in all classes of munitions, but there could be no wholesale substitution of any other material. As a result, on a percentage basis the over-all conservation of steel by Ordnance was small—less than 5 percent of the computed requirement of 14 million tons for the year 1943. But that 5 percent amounted to 622,000 tons, roughly equal to the weight of finished steel in 13,000 medium tanks. During 1942, before steel conservation measures had become fully effective, the saving amounted to 96,000 tons.23

More important than the over-all saving of plain carbon steel was the saving of strategic alloys, particularly nickel, chromium, vanadium, tungsten, and molybdenum. Here the Ordnance Department made an impressive record. A comparison of 1943 requirements for nickel as computed before and after conservation measures were applied shows a drop from 40,000 tons to 14,000 tons; with vanadium the same comparison shows a drop from nearly 750 tons to 250 tons; with molybdenum a reduction from 10,500 tons to 8,000 tons. The saving of molybdenum was comparatively small because, at the beginning of the war production program, molybdenum was abundant and was freely used as a substitute for other ferroalloys. It was not until the summer of 1942 that this increased use of molybdenum caused a shortage for a few months and brought the need for conservation measures.24

Ordnance had two primary uses for tungsten—ammunition, and tool and die steels. As early as spring 1941 the arsenals were directed to reduce their use of tungsten in tools and dies wherever possible, but the savings in this area were necessarily limited.25 It was in production of armor-piercing small arms bullet cores, and in certain types of artillery ammunition, that the greatest savings were made. At the beginning of the defense period an

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electric-furnace steel known as WD 74100, containing up to 4 percent tungsten, was used for all armor-piercing small arms cores, although Frankford Arsenal and Watertown Arsenal had experimented with many other types of steel during the 1920s and 1930s and had found some to be nearly as good as the tungsten steel.26 As the volume of small arms production rose steadily in 1940 and early 1941 and tungsten became extremely scarce, Ordnance switched from tungsten steel to manganese-molybdenum steel for armor-piercing cores. This effected an estimated saving of over 7,500 tons of tungsten in 1942–43 production.27 When electric-furnace steel-making capacity became critical, Ordnance engineers discovered they could make satisfactory cores for both .30-caliber and .50-caliber ammunition from open-hearth manganese-molybdenum steel. Later, acceptable .30-caliber cores were made from high-grade carbon steel without the addition of any alloys at all. As a result of these efforts, satisfactory bullet cores were produced without using either critical alloys or electric-furnace capacity—and, in the process, the rate of production increased and the cost per unit decreased.28

Among the military agencies, Ordnance took the lead in conserving steel and its alloys, but the development of low-alloy steels was a broad national effort in which the Department was but one keenly interested participant.29 The American Iron and Steel Institute, the War Production Board, and many other agencies, both public and private, cooperated in producing, testing, and cataloguing many types of steels using minimum quantities of scarce alloys, the so-called National Emergency (NE) steels. These steels not only used less of the alloying elements but were compounded with alloy scrap to save virgin alloy metals. Ordnance adopted and used these lower-alloy steels in thousands of items and parts of items without sacrificing performance capabilities. On a single piece of equipment the saving brought by the substitution was often small, but when multiplied by millions of items it added up to substantial quantities of scarce material. When, for example, a National Emergency steel was substituted for a chrome-vanadium steel in the operating rod handle of the M1 rifle, the saving in the course of a year amounted to several tons of chromium and vanadium on this one part alone. In the 90-mm. antiaircraft gun several parts were made of low-alloy NE steels and others of plain carbon steel with an estimated saving during 1943 of 150 tons of critical nickel. In breechblocks for the 75-mm. and 76-mm. guns the quantity of nickel required per thousand blocks was reduced from 3,500 pounds to 700 pounds, and proportionate reductions were made in recoil, recuperator, and counter-recoil cylinders. In the production of .50-caliber and ,30-caliber machine guns, large savings resulted from the use of pearlitic malleable iron castings.30 The ease with which this type of malleable iron could be fabricated made it particularly valuable for machine gun production and led to its substitution for alloy

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steel in the trunnion blocks and in the side, top, and bottom plates of the caliber ,30 and caliber .50. Use of castings in place of machined steel forgings for each heavy-barrel .50-caliber weapon saved, in weight of material machined off, 37 pounds as well as considerable manpower and machine-tool time, both of which were critical.31

Important as such savings were, however, the greatest conservation of steel alloys was not made in small arms or artillery items but in tanks, trucks, and artillery ammunition. Ordnance used more steel of all kinds for tanks and trucks than for any other single purpose—approximately 7,000,000 tons during 1943. For artillery ammunition it consumed over 4,000,000 tons during that year as compared with less than 1,000,000 tons for artillery and approximately 1,550,000 for small arms.32

In tank production, the greatest savings of strategic metals were made by using low-alloy armor plate. At the start of the World War II production program it was not customary for the Ordnance Department to specify the chemical composition of the armor plate it purchased, nor to prescribe the processing methods used by manufacturers. The only requirement was one of performance. Each armor producer used a steel-making formula that differed in some respects from those used by other armor producers. But all the compositions had one characteristic in common: all were rich in nickel, chromium, and vanadium, some containing as much as 5 percent nickel.33 “The main consideration,” wrote the Ordnance Materials Branch, “was to produce good armor plate without regard to cost or strategic alloys.”34

In 1941, when the Tank and Combat Vehicle Division of Ordnance surveyed the formulas used by manufacturers of armor plate and compared the quantities of ferroalloys required for each tank with the existing schedules for tank production, it became apparent at once that sufficient quantities of alloys would not be available to produce tanks with such steel. The same survey supported the idea that rather large reductions in the alloy content of armor plate could be made without lowering the ballistic quality. Shortly after Pearl Harbor, when the shortage of steel alloys became acute, Ordnance directed its armor producers to keep their use of alloys below certain percentages. At the same time, because there were not enough facilities to produce rolled armor in the enormous quantities needed for the tank program, Ordnance turned to the use of cast-steel armor. Thousands of ballistic tests proved that cast-steel armor was more than 90 percent as efficient as rolled armor, and that it had distinct advantages when the design called for curved surfaces. Acceptable cast armor was made without any vanadium and with only .5 percent nickel and .5 percent chromium.35 Changes in armor composition brought the need for developing new welding materials and techniques, since low-alloy armor could not be successfully welded by the same

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Chart 11: Steel alloys 
required per medium tank (M4) with and without conservation measures

Chart 11: Steel alloys required per medium tank (M4) with and without conservation measures

Source: Quarterly Review (December 1949, Chart 34. I)RI AGO.

methods used with high-alloy armor.36

In analyzing the automotive components of tanks—the transmissions and differentials as distinguished from armor plate and guns—the Society of Automotive Engineers War Engineering Board gave invaluable assistance. This board was composed of top-flight engineers from all the leading automobile companies, and its purpose was to make available to the Army, without cost and with a minimum of red tape, the best technical advice on automotive engineering. Among scores of projects undertaken by this board for the Ordnance Department was one designed to reduce the quantities of critical materials used in tanks. In September 1942 the War Engineering Board appointed four subcommittees to study conservation of materials in the tank—one committee each for track, suspension, transmission and final drive, and miscellaneous (turret, gun mount, traversing and elevating mechanism).37 Each committee determined the maximum stress to which each part would be subjected while in use and recommended that it be made of steel just strong enough to do the job required of it. In 1943 alone, it was estimated that the work of these committees on the M4 tank resulted in the saving of 3,500 tons of nickel, 1,000 tons of chromium, and 500 tons of molybdenum.38

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In artillery ammunition, one of the earliest and largest savings resulted from the elimination of nickel in 75-mm. and 3-inch armor-piercing-capped shot. Before the war, shell manufacturers had used steel containing a high percentage of nickel, averaging 3.5 percent, but, as tests showed that nickel was not needed to produce shot with the required ballistic properties, the use of nickel steel in shot bodies was discontinued in April and May 1942.39 According to estimates, during the next eighteen months this one change saved nearly 4,000 tons of nickel. A similar change was made in the smaller 37-mm. armor-piercing-capped shot bodies; a steel containing up to 4 percent tungsten was replaced by a chrome-molybdenum steel when tungsten became very scarce. In the latter half of 1942 the Ammunition Branch carried on an important project to conserve molybdenum in the production of bomb bodies. Ordnance engineers determined that, by using heat treatment, it was possible to make satisfactory bomb bodies from plain carbon steel, and after the first of May 1943 all bomb steel was of this type. The saving of molybdenum during 1943 exceeded 1,000 tons.40

The success of Ordnance efforts to conserve ferroalloys was officially recognized in the spring of 1943 by the commanding general of the Army Service Forces. In response to a memorandum from General Campbell outlining some of the achievements of the Department in conserving steel alloys, and reporting arrangements that had been made to place British and Canadian technical representatives on various Ordnance conservation committees, General Somervell wrote: “Congratulations on the splendid results achieved in conservation of critical materials by the Ordnance Department as outlined in your memorandum. ... You are to be commended for extending these conservation activities to our Allies by placing British and Canadian technical representatives on Ordnance Department committees.”41

Copper and Its Alloys

Of the nonferrous metals, Ordnance used more copper than anything else. It used more copper than all the other technical services combined, taking between 75 and 85 percent of the entire Army allotment. The bulk of the copper allotted to Ordnance early in the war went to make brass cartridge cases, and to make gilding metal, another copper-zinc alloy, for small arms bullet jackets. Early in 1942, as requirements for ammunition mounted into the billions of rounds, Ordnance production schedules called for the use of 800,000 tons of copper in 1942, and nearly twice that amount during 1943.

During the 1920s and 1930s copper and zinc had not been considered by the War Department as strategic materials that might be unavailable in time of war.42 It was recognized that tremendous quantities of copper would be required for ammunition, naval vessels, and electrical equipment, but, as the United States was a leading producer of copper and South

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Chart 12—Percent 
distribution of copper used, by army agency: 4th quarter, 1943*

Chart 12—Percent distribution of copper used, by army agency: 4th quarter, 1943*

* CMP budgeted allotment to Army was fora monthly average use of 163,721 tons.

** Transportation, Quartermaster, and other Amy Agencies.

Source: Quarterly Review (December 19441, Chart 10-B, DRB ADO.

America was a major foreign source of supply and one from which the United States was not likely to be cut off in time of war, the possibility of a crippling shortage seemed remote.43 Even as late as January 1940 copper and zinc were not included on either the strategic or critical lists prepared by the Army and Navy Munitions Board, but after adoption of a multibillion-dollar munitions production program in the summer of 1940 the picture began to change. In the spring of 1941, with lend-lease requirements added to the needs of United States forces, Ordnance was informed that zinc was henceforth to be used only when no satisfactory substitute could be found, and during the summer the threat of an eventual copper shortage had to be considered.

The Ordnance program to conserve copper during World War II covered a wide front and involved innumerable substitutions and design changes. Some netted large savings while others brought only small reductions in requirements, but they all helped in some measure to stretch the available supply. A booster for high-explosive shells, for example, was converted from brass bar stock to a steel stamping with estimated savings of 83,000 tons of brass in 1943 production. Changing a gasoline tank cap and strainer from a machined brass casting to a low-carbon steel stamping for certain types of vehicles saved several hundred tons of brass, and substitution of steel for copper in radiators of trucks netted even greater savings.44

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Chart 13: Percent 
distribution of copper used by Ordnance Department, by type of matériel: 4th Quarter, 1943*

Chart 13: Percent distribution of copper used by Ordnance Department, by type of matériel: 4th Quarter, 1943*

* CMP budgeted allotment to Ordnance Department was fora monthly average of 122,627 tons.

Source: Quarterly Review (December 1943). Chart 19-B. DRB AGO.

Steel Cartridge Cases

The Ordnance Department’s most far-reaching effort to conserve copper was the program to manufacture cartridge cases of steel instead of brass. Before 1940 cartridge cases had been made almost exclusively of brass because only brass possessed the peculiar physical characteristics required. The wall of the case, for example, must be elastic enough to expand under pressure and then contract instantly when the pressure is released. The expansion is necessary to provide obturation during firing, that is, a tight seal against the breech wall of the weapon to prevent any gases from being driven back into the breech. After firing, the empty case must snap back to its original size so that it may be readily ejected from the gun. Because of the high pressures generated within the case when the powder ignites, the case must have great tensile strength at the head end, but the mouth must be annealed to much lesser strength to permit the necessary expansion. Cartridge cases made of brass not only met these exacting requirements but also possessed other advantages. They did not rust when exposed to the elements. After firing, brass artillery cases could be cleaned and used over and over again. Brass cases were relatively easy to manufacture and a well-established brass industry stood ready to supply the essential alloy stock for the purpose.45

The manufacture of steel cases was not

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altogether new in 1941, but it was nearly so, A few steel cases for artillery ammunition had been made in the United States and Germany during World War I, but the results had not been altogether satisfactory in either country.46 Because of the abundant supplies of copper and zinc available to the United States, and the many difficulties inherent in the use of steel cases, little attention was paid to the matter during the years between the wars. In 1939 and 1940 a few cases made of seamless steel tubing were submitted to the Ordnance Department by commercial producers for test but none proved satisfactory. As a result, when Ordnance engineers and representatives of industry were suddenly faced in 1941 with the problem of manufacturing steel cases they had to begin virtually from scratch.

The problems involved seemed at first to be insurmountable, It was, of course, essential that the steel case be just as effective as the brass. No substitution that impaired the performance of ammunition in combat could even be considered. Further, the steel case had to be perfectly interchangeable with the brass case in order to simplify its use on the battlefield. To achieve these results, it was necessary to develop a new type of steel with the elasticity required of cartridge cases—and do it without using appreciable quantities of critical alloying elements or scarce heat-treating equipment. New techniques for deep drawing steel had to be devised and tested, and a protective coating had to be developed for application to the finished case to prevent corrosion. Following the solution of these and other design problems it was necessary to devise manufacturing processes that would make the substitution of steel for brass feasible in terms of cost, machine tools, and manpower, and also in terms of volume production running into millions of rounds per month, Finally, it was highly desirable, if not actually mandatory, that the manufacturing techniques be of such a nature that the facilities already engaged in the manufacture of brass cases could be used, with a minimum of readjustment, to produce steel cases.47

Artillery Cases

Since the artillery cases appeared to raise fewer problems than did small arms cases, they were attempted first. After a period of unsuccessful experimentation with low-carbon steel, small quantities of acceptable artillery cases were produced by the fall of 1941 from heat-treated mild alloys.48 Experimentation was then directed toward the production of cases from medium-carbon steel with only manganese added, and by January 1942 General Barnes was able to report to Mr. William S. Knudsen, cochairman of OPM, that the results of experimental work done up to that time indicated that artillery cases of all sizes from 20-mm. through 105-mm, could be made of steel, at least in small quantities.49 When this report came to the

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attention of the Under Secretary of War, he immediately directed the Chief of Ordnance to make plans for converting production of all artillery ammunition to steel on short notice. He mentioned the growing shortage of copper and cited the fact that the Ordnance ammunition program was at that time taking 86 percent of all copper allotted to the Army.50

All during the first half of 1942 Ordnance had to carry on its steel ammunition project under constant pressure to accomplish in a few months what normally would have taken years. Because of the activities of enemy submarines in the Western Hemisphere, the loss of Chilean copper imports was considered a possibility early in 1942; at the same time, the ammunition requirements for the United States armed forces and for the supply of friendly nations reached astronomical proportions. The situation became so critical that not only did Mr. Patterson and Mr. Knudsen take a keen interest in it but Vice Presidcnt Henry A. Wallace also gave it his personal attention early in April.51 In May 1942 the chief of the Small Arms Branch of the Industrial Service reported that both the Lake City and the Denver Ordnance Plants were operating with less than one week’s supply of brass, and that it appeared probable that both would have to shut down before the end of the month for lack of material.52 Under these circumstances the development process was streamlined, research and production being telescoped to a remarkable degree.

Because of the urgency of the situation there was a tendency to minimize the many technical difficulties inherent in the production of steel cases and to adopt an overly ambitious conservation program. Work was begun on all sizes of artillery cases from the 20-mm. up through the 105-mm., and in May 1942 a report to the ASF chief of staff stated: “Mass production of all cartridge cases (except 3-inch, 90-mm. and small arms) will be realized during 1942. ... Steel cases are through the talking stage and are now production items.”53 But more than a year later the chief of the Ordnance Ammunition Branch had to report that, “with the exception of the 20-mm. cases, rejections arc still running at rather high rates, indicating that there is still a large amount of development work to be completed before steel cartridge cases will be produced in sufficient quantities to meet the Army Supply Program.”54

The Ordnance Department did not presume to carry on this project alone but enlisted the aid of private industry, particularly steel producers and steel fabricators. By May 1942 contracts had been let with many different companies for production of 20-mm., 37-mm., 40-mm., 57-mm., 75-mm., and 105-mm. cases, and a Cartridge Case Industry Committee had been formed to serve as a central clearing house of information on the manufacture of steel

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Table 13—Steel Cartridge Cases In World War II

Weapons and Cartridge Case Models Attempted Standardized In Production
20-mm. Aircraft guns, M21A1B1 case substitute yes
37-mm. Subcaliber guns, MK 1A2B1 case no yes
37-mm. Aircraft guns AN—M10, MK III A2B1 case substitute yes
37-mm. Tank and AT guns, M 16B1 case substitute yes
37-mm. Aircraft AN—M9 guns and AA guns, M 17B1 case substitute yes
40-mm. AA guns, M 25B1 case standard yes
57-mm. AT guns, M 23A2B1 case no yes
57-mm. Recoilless rifles, M 30A1 case standard yes
75-mm. Howitzers, M 5A1B1 case no yes
75-mm. Field guns, M 18B1 case substitute yes
75-mm. Recoilless rifles M 31A1 case standard yes
3-inch AA and AT guns, MK II M 2B1 case standard yes
90-mm. AA and Tank guns, M 19B1 case no no
105-mm. Howitzers, M 14B1 case substitute yes
105-mm. M27 Recoilless rifles M32 case no no

Source: Ammo Br, Ind Div, OCO.

cases.55 This group acted in an advisory capacity to all concerns engaged in cartridge case manufacture and helped solve technical problems as they arose. A similar committee was formed by the producers of the steel used in cartridge cases and another by the manufacturers of the finishes used to prevent corrosion. The members of these committees were representatives of companies that were normally competitors but they unstintingly shared their technical knowledge to advance the production program.56 As a result of these efforts, thirteen types of steel artillery cases reached the stage of quantity production, (See Table 13.) Of this number, ten were given some degree of official acceptance by action of the Ordnance Committee. The cases for the 40-mm. AA gun, the 57-mm, recoilless rifle, the 75-mm. recoilless rifle, and the 3-inch AA and AT gun were accepted as fully standard while the other six were classified as substitute standard.

Small Arms Cases

The development of steel small arms cases was carried on concurrently with the development of steel artillery cases, but, with the exception of one caliber, progressed more slowly.57 Because of the extremely high pressures generated in small arms cartridges, the substitution of steel for brass posed more difficult problems than it did in artillery cases. At the outset of the project a broad division of labor between

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government and industry was agreed upon: development of commercial types of ammunition, such as shot-gun shells and the .22-caliber, was left largely to the commercial arms manufacturers while Ordnance facilities centered their attention on the .30, .45, and .50-calibers.58

Of all the small arms cartridges, the .45-caliber, a short, squat case, proved to be the easiest to convert to steel. Development work at Frankford Arsenal proceeded rapidly during 1941 and early 1942, and by the summer of 1942 the steel case went into production at the Evansville Ordnance Plant.59 Other plants were soon added and by June 1943 over one billion cases had been produced. After thorough testing by the using arms, as well as by Ordnance, the .45-caliber steel case was accepted as standard in January 1943.60

Research on the .30 and .50-caliber cases was carried on at Frankford Arsenal and at four government-owned contractor-operated plants—Milwaukee, in Wisconsin, Lowell in Massachusetts, Denver in Colorado, and Twin Cities in New Brighton, Minnesota. A host of technical problems arose with these calibers. One of the most difficult resulted from the inelasticity of steel, which caused the cases to expand and stick in the chamber after they were fired. A great deal of effort still had to be put into development of a suitable protective finish for the steel cases. Nevertheless, by the spring of 1943 the Ordnance Department reported that .30 and .50-caliber ammunition was “passing from the research stage into the production development stage.”61 Several million .30-caliber steel cases and a quarter of a million ,50-caliber cases had been produced, and schedules calling for the manufacture of 150 million rounds of .50-caliber and 210 million rounds of .30-caliber per month during the latter half of the year had been established. Arrangements were being made to submit both calibers to the using arms for test, with the expectation that they would be accepted first for training purposes and then, as improvements were introduced, for unrestricted combat use.62

At this stage in the process a sudden shift in plans occurred. In May 1943, at the recommendation of Brig. Gen. James Kirk, chief of the Ordnance Small Arms Branch, the scheduled production of .30 and ,50-caliber steel cases was slashed from a total of 360,000,000 per month to 125,000,000. General Kirk reasoned that the new rate of production would be high enough to establish the feasibility of producing small arms ammunition with steel cases but low enough to eliminate the possibility of producing large quantities of ammunition that might, “because of the present state of the art, and lack of standardization, be a more or less complete loss.”63 This decision was the beginning of the end of the production of steel cases, both small arms and artillery, in World War II. A further drop in the production schedule occurred in July and by November 1943 all work on the .30 and .50-caliber steel cases was stopped except for experimental production lines at

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Frankford Arsenal. Three factors prompted this action: inferiority of most steel cases to brass cases, increased availability of copper resulting from greater production by copper mines and effective conservation efforts, and a sharp reduction in over-all requirements for small arms ammunition.64

Although a great deal of progress was made in converting cartridge cases from brass to steel, it was never possible to produce enough acceptable steel cases. The ambitious goals established for the steel-case project early in 1942 were not attained. To meet the requirements of the Army Supply Program, Ordnance had to continue the production of brass cases up to the limit of its brass allocation.65 The value of the steel-case program was that it supplemented, rather than replaced, brass production. In addition, the wartime experience with steel cases led eventually to a fresh attack on the problem, in which Army and Navy cooperated, in the postwar years.66

Bullet Jackets

Another major step taken by Ordnance engineers to conserve copper was the substitution of clad steel for gilding metal in small arms bullet jackets. For many years before World War II, the lead or steel core in small arms ammunition was covered with a jacket of gilding metal composed of 90 percent copper and 10 percent zinc. The gilding-metal jacket was needed for two reasons: to provide a soft coat for the bullet core and to give the projectile the desired shape. A bullet hard enough to give good penetration of the target was too hard for the rifling in the bore of the weapon. In flight, a long slender bullet encountered less air resistance and was more stable, but a blunt-nosed bullet gave better penetration of the target. These conflicting requirements were met by forming the bullet core of hard steel shaped to give maximum penetration and then covering it with softer gilding metal shaped to give the best flight characteristics. Any space within the jacket not filled by the steel core was filled with lead alloy, partly for ballistic balance and partly for improved penetration.67

In searching for a substitute for gilding metal, Frankford Arsenal had produced steel jackets plated with cupro-nickel as early as 1898, and had tested various types of cupro-nickel-clad steel cases during the 1920s and 1930s, but without much success.68 In 1941 experiments were made in the use of steel jackets coated with copper and others coated with gilding metal, and Ordnance engineers, working in close cooperation with metallurgists from private industry, soon developed a copper-plated steel jacket for .45-caliber bullets that went into production in the summer of 1942. The base material was a low-carbon steel with a very thin coating of electro-deposited copper on both sides. This copper-plated ammunition was promptly accepted by the using arms, and within a few months all .45-caliber ammunition in

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Chart 14: Copper 
requirements for ordnance matériel: 1943

Chart 14: Copper requirements for ordnance matériel: 1943

Source: Quarterly Review (December 1943), Chart 20-B, DRB AGO.

production was copper plated.69 For .30 and .50-caliber, progress was slower, but a satisfactory steel jacket coated with gilding metal was put into production in the fall of 1942. Both it and the copper-coated jacket could be made with 75 percent less copper than was needed for the solid gilding-metal jacket.

As the accompanying chart indicates, the greatest savings of copper in Ordnance production were made by the Small Arms Branch, which cut its consumption during 1943 by approximately 100,000 tons. This feat was achieved largely by the successful development of steel cartridge cases for .45-caliber ammunition and the conversion to steel or gilding-metal-clad steel for bullet jackets. The saving of copper in the artillery ammunition program was less, approximately 75,000 tons in 1943; the saving of copper in artillery and in tanks and vehicles was small chiefly because these classes of matériel were not large consumers of copper. The success of Ordnance efforts to conserve copper, coupled with increased production by the copper industry, resulted in a marked improvement in the copper supply picture in the fall of 1943. By December the Ordnance Materials Branch was able to report that it was “no longer necessary to use substitute materials for military applications where copper and copper alloys will provide better military characteristics and increase the useful life of matériel,”70

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Chart 15: Percent 
distribution of aluminum used, by army agency: 4th quarter, 1942*

Chart 15: Percent distribution of aluminum used, by army agency: 4th quarter, 1942*

* Excludes Army Air Forces. Remaining Army monthly average consumption was 15,863,000 pounds.

** Transportation, Medical, and Engineers.

Source: Quarterly. Review (December 1943). Chart 13-A. BRE AGO.

Aluminum

Aluminum did not appear on War Department lists of strategic materials until the year 1936, but after that date it rapidly came to the front as one of the most critical materials in the war production program.71 In the fall of 1940 production of aluminum was barely sufficient to meet the demands for the aircraft program, which was given first priority for primary aluminum. In the spring of 1941 the Under Secretary of War and the Office of Production Management called the aluminum shortage to the attention of the supply arms and services and directed them to eliminate aluminum from their equipment wherever possible by substituting other less critical materials such as iron, steel, wood, and plastics.72

The Ordnance program to conserve aluminum actually began in the spring of 1941 when a survey of all Ordnance items containing aluminum or other critical material was undertaken. As a first step in the program, all aluminum parts were examined with a view to determining which could be made of some less critical material without sacrifice of military efficiency. When this study was completed shortly after Pearl Harbor, it revealed that such substitutions could be made without significant design changes in 337 aluminum parts with an estimated saving on planned production of 20,000 tons of aluminum.73 Small arms ammunition chests, for

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Chart 16: Percent 
distribution of aluminum used by the Ordnance Department, by type of matériel: 4th quarter, 1942*

Chart 16: Percent distribution of aluminum used by the Ordnance Department, by type of matériel: 4th quarter, 1942*

* Total Ordnance monthly average consumption was 9 ,500,000 pounds.

Source: Quarterly Review (December 1943), Chart 14-A, DRB AGO.

example, could be of steel rather than aluminum; handles of inspection gages could be converted from aluminum to plastic; steel and plastic might be substituted for aluminum in parts of bomb fuzes and mortar fuzes; and malleable iron and steel used in parts of gun mounts and carriages.74 By eliminating aluminum in the platform, handwheels, and miscellaneous parts of the 90-mm. gun mount, the quantity of aluminum required for this one item was reduced from over 400 pounds to about 25 pounds per mount.75 The second step in the Ordnance campaign to conserve aluminum was to study those items in which substitute materials could not be used without significant design changes or elaborate tests. The items offering the least difficulty were to be investigated first and those that were expected to entail complications were left until later. As the two largest consumers of aluminum in the Ordnance Department were the Ammunition Division and the Tank and Combat Vehicle Division, efforts were concentrated on the items procured by these two divisions. By February 1942 General Barnes was able to report that aluminum had been largely eliminated from tanks and combat vehicles except for fans, transmission

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housings, and motors, and that new motors using less aluminum were under development. In artillery ammunition the situation was different. “Reductions of aluminum for ammunition will in general be difficult to make,” General Barnes wrote, “since this metal was built into the designs of fuzes and other intricate parts of high explosives ammunition. Fuzes and similar components were developed only after years of experimentation. Considerable time will be required for tests of redesigned parts to determine whether the substitutions will be feasible.76

One of the earliest substitutions for aluminum in artillery ammunition was the adoption of the plastic M52 fuze for the 60-mm. and 81-mm. mortar shell. After extensive proof firings, the plastic fuze went into production early in 1942 with a saving of approximately one pound of aluminum for each fuze, or a total of 17,500 tons in 1942–43. The body of the M54 fuze was converted from aluminum bar to a forging with further substantial savings. The windshields of 75-mm. armor-piercing-capped shot M61, formerly made of primary aluminum, were converted to steel with estimated savings of 4,500 tons of aluminum during 1943. Steel also replaced aluminum in firing pins for artillery ammunition.

There were many other such substitutions, but the principal saving in artillery ammunition did not come from the substitution of some other material; it came from the use of secondary rather than primary aluminum. The use of secondary aluminum was made possible by application of the die-casting process by which the metal could be formed into intricate shapes needing little or no machining. Ordnance engineers encountered two major problems in adapting the die-casting process to munitions production. They had to modify the design of the items to make them suitable for die-casting, and they had to develop new casting alloys that could be made from aluminum scrap containing a high percentage of impurities. Experts from the die-casting industry cooperated with the Ordnance Department in solving both problems. One of these industrial experts, Mr. William During, initiated many design modifications while serving as a consultant on die-casting to General Barnes. An extensive experimental and test program had to be completed before a high-strength alloy capable of producing sound castings of intricate shapes and thin wall sections was developed. This alloy was used successfully from September 1942 until the end of the war, and in the postwar years became the standard aluminum alloy for industrial die-casting.77

As with all manufacturing processes that use dies, aluminum die-casting was not economically feasible for producing items in small quantities, but was well suited for the mass production required during World War II. Substitution of secondary aluminum die-castings for parts machined from primary aluminum bar stock netted a saving not only from the use of lower grade material but also from elimination of the scrap losses incurred in machining operations. “By comparison with screw machine procedure,” the Ordnance Department reported in June 1942, “die-castings require only a 10 percent excess in raw material as compared to net weight of finished product, and half of this is ordinarily re-cast in subsequent operations. Bar stock scrap runs from 30 to 300

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percent, and this waste becomes secondary scrap and is lost to the virgin metal market.”78

When aluminum requirements for 1942, computed before conservation measures were adopted, were compared with the quantity of aluminum actually used in Ordnance production during the year, the over-all saving was roughly 14,500 tons. (See Chart 17.) The same comparison for the year 1943 showed a saving of 62,500 tons, of which approximately 45,000 tons were in ammunition and 15,000 in tanks and other vehicles. Even these large figures do not indicate the full extent of Ordnance conservation of aluminum, for they do not show the saving of primary aluminum that resulted from the use of less critical secondary aluminum in die-castings. By the fall of 1943 nearly 60 percent of all aluminum used by the Ordnance Department was of secondary grade.79

While Ordnance engineers were doing everything possible to conserve primary and secondary aluminum, equally significant efforts were made by the aluminum industry to increase production. Total national production of aluminum more than doubled in the eighteen months between January 1942 and June 1943, from about 45,000 tons a month to nearly 95,000 tons a month, and further increases were made in the latter half of 1943. As a result, the aluminum crisis ended that summer. “The increased production of aluminum, combined with effective conservation,” the Ordnance Department reported in September, “has resulted in aluminum becoming readily available and non-critical at the present. ... Under these circumstances additional conversions and substitutions are unnecessary, although downgrading to the lowest purity limits practicable is desirable.”80

Rubber

In terms of strategic materials, the most serious consequence for the United States of the outbreak of war with Japan and the subsequent Japanese advances into Malaya and the East Indies was the loss of crude rubber imports. Although the nation had on hand in December 1941 the largest stockpile of natural rubber in its history about 527,000 tons—this reserve amounted to less than one year’s supply. Small quantities of natural rubber could still be imported from Latin America, Liberia, and Ceylon; a certain amount of reclaimed rubber became available each year; and a few thousand tons of synthetic rubber could be produced by existing facilities. But none of these sources was more than a drop in the bucket when compared to the enormous military and civilian requirements for rubber in 1942.

The rubber crisis was of particular concern to the Ordnance Department because at the start of the war it was, among Army agencies, the second largest user of crude rubber, taking about 20 percent of the total Army allotment.81 At that time it used rubber primarily for tires on combat vehicles, for track blocks, bushings, and bogies of tanks, and for hundreds of miscellaneous items such as gaskets, hoses, fan

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Chart 17—Aluminum 
requirements for ordnance matériel: 1943

Chart 17—Aluminum requirements for ordnance matériel: 1943

Source: Quarterly Review (December 1943), Chart 19-B, DRB AGO.

belts, and electrical cables. In the summer of 1942 when Ordnance took over from Quartermaster the responsibility for motor transport vehicles, including the procurement of millions of tires and tubes, it became by far the largest user of rubber in the Army, taking between 80 and 90 percent of the Army allotment.82 Thereafter the task of conserving the Army’s limited allotment of crude rubber was almost exclusively an Ordnance responsibility.

Both the Quartermaster Corps and the Ordnance Department had inaugurated rubber-conservation programs long before the attack on Pearl Harbor. As early as 1936 Ordnance had tested tires with synthetic tread for the 75-mm. gun carriage, and in 1941 had launched a survey of all Ordnance items made of rubber with a view to substituting synthetic rubber or some other material wherever possible. Late in 1941 the Quartermaster Corps had inaugurated a program for repairing and recapping all Army tires that were worn or damaged, and had taken steps to improve tire maintenance in the field. But an all-out effort to conserve rubber in military equipment did not begin until after Pearl Harbor. Then, under pressure of necessity, means were found to produce the essential tires, tank tracks, and other items needed by the armed forces before the national stockpile of crude rubber was exhausted.

There were many ways in which small savings of rubber could be made by changing the specifications for Ordnance

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equipment. In some parts, reclaimed rubber could be used instead of new rubber; in others the quantity of rubber could be decreased without serious loss of efficiency; and instill others some substitute materials such as felt or paper could be used in place of rubber. In April 1942, for example, the Small Arms Branch revised its specifications for recoil pads and water chest hoses to permit the use of reclaimed rubber in these items with estimated savings during 1942–43 of more than 1,000 tons of natural rubber. By reducing the amount of rubber in adhesive tape used for ammunition packaging, and at the same time using a higher percentage of reclaimed rubber, the Ammunition Branch reported in the spring of 1942 that it would save 800 tons of natural rubber. A steady flow of such conversions and substitutions continued throughout 1942 and 1943 until practically all the so-called mechanical rubber items were converted to some other material. While these measures helped to conserve the nation’s stockpile of natural rubber, their total effect was small. They were undertaken because no one knew when the war would end, how long the stockpile of rubber would last, or when the day might come when the saving of even a single pound of crude rubber might be important.

Synthetic Rubber

Far more important in the long run was the conversion from natural to synthetic rubber, but this step could not be taken during 1942 because synthetic rubber simply was not available in large quantities. The synthetic rubber industry in the United States was still in its infancy and much remained to be learned of the physical properties of the various synthetic compounds. Annual production was only about 8,000 tons—roughly 1 percent of the yearly consumption of natural rubber—and large-scale production could not be achieved until new plants to produce the most promising types had been constructed.83 After synthetic rubber became available, elaborate tests had to be made under simulated combat conditions to determine how it could best be used in military equipment. In this long and complicated process the rubber industry, various executive agencies of the government, and the Ordnance Department maintained the closest cooperation. In government-owned plants the rubber industry produced huge quantities of synthetic rubber. As far as Ordnance items were concerned, rubber companies manufactured the tires, tubes, and other synthetic products in their own factories and provided the laboratory test facilities; Ordnance supplied the test vehicles and proving grounds and bought the experimental products.

The four synthetic rubber compounds most widely used by Ordnance were GR-S (Buna-S), GR-M (neoprene), GR-N (Buna-N), and GR-I (butyl).84 Each had many of the qualities that made natural rubber a useful industrial material, but none proved to be a perfect substitute. GR-M was more like natural rubber than any of the other synthetic materials, and

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was, in addition, more resistant to oil and flame. But it had one serious defect—at extremely low temperatures it became hard and brittle.85 When this fact was revealed by tests, further use of GR-M for tires was canceled, and it was thereafter limited to items such as V-belts, radiator and brake hoses, vibration insulators, fire control cables, and sponge rubber for seats and crash pads. Although GR-N was suitable for tires, it was used exclusively for mechanical rubber items because it could not be produced in the large quantities needed for tire manufacture. GR-S, made from petroleum and alcohol, was selected for tires and tank tracks partly because of its physical properties and partly because it could be manufactured more easily than any of the other compounds. During World War II about 90 percent of all synthetic rubber produced in government-owned plants was GR-S, but it was stiffer than natural rubber and when flexed rapidly and continuously it generated excessive heat. Tire tread made of GR-S was not only easily chipped by stony terrain but also required a thin layer of natural rubber between it and the carcass to provide proper adhesion. It tore too readily to be a good material for inner tubes, and was hard to repair because of its lack of adhesiveness. As the quality of GR-S was improved by industrial chemists, it came to be the standard synthetic for military tires and tank tracks, but as a material for inner tubes it was replaced in 1944 by GR-I, which held air even better than did natural rubber and could be patched more easily than GR-S.

Combat Tires and Tank Tracks

Before the transfer of motor vehicles to Ordnance in August 1942, Ordnance rubber-conservation efforts were centered mainly on combat tires and tank tracks. The combat tire was given particular attention because it used almost twice as much natural rubber as did the standard type of highway tire. Designed to run flat for 75 miles after being punctured, it had thick sidewalls that provided support for the vehicle while the tire was run flat. As a substitute for the combat tire, Ordnance experimented after Pearl Harbor with the use of so-called restrictor rings on standard tires. These were steel flanges which, securely fastened to the rim, partially encased the sidewalls of the tire. When the tire was punctured the restrictor rings gave enough support to prevent complete collapse of the tire, but their development was discontinued after tests showed that they caused steering difficulties, increased the danger of axle breakage, and made impossible the use of chains for driving on muddy ground.86 Fruitless efforts were also made to conserve rubber by developing a tubeless combat tire. As a result, during 1943 it became necessary to sacrifice quality for quantity. The requirement that the tire run flat for 75 miles was cut to one of 40 miles, thus reducing substantially the amount of rubber needed for each tire.87 About the same time, the number of combat tires to be manufactured was reduced when the War Department announced that such tires would no longer be required on various gun carriages. Toward the end of the year, when acceptable combat tires made of synthetic rubber came into production, the combat tire ceased to be a serious problem.88

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While these efforts went forward to conserve rubber in combat tires, Ordnance engineers also turned attention to the use of steel tracks to replace rubber tracks on tanks. Although steel tracks did not entirely eliminate the requirement for rubber, since they had to be fitted with rubber bushings, their use nevertheless brought an important saving of rubber. Steel tracks had disadvantages, however, and for some purposes were not as satisfactory as rubber tracks. They gave less protection to the suspension components, for example, and provided poorer traction on pavement and on ice and snow. These facts, coupled with the dwindling supplies of natural rubber, pointed inescapably to the conclusion that tank tracks had to be made of synthetic rubber.

During the winter of 1942–43, when improved synthetic rubber came into production, Ordnance launched an extensive program to develop and test synthetic tracks. By October 1943 the performance of the synthetic smooth block T16 for the light tank was so satisfactory that it was approved for use, and by May 1944 the synthetic smooth block T51 for the medium tank was approved. For half-track vehicles, one third of the production schedule was switched to synthetic in October 1943 and by May 1944 the proportion of synthetic production had risen to two thirds. When Allied forces in Italy reported their preference for steel rather than rubber tracks for use on rocky, mountainous terrain, Ordnance produced a rubber-backed steel track for medium tanks that helped reduce the wear on bogie wheels encountered in the use of all-steel tracks. Production of acceptable chevron-type tracks of synthetic rubber proved difficult and was not achieved until near the end of the war. The use of synthetic rubber for bogie wheel tires was also hard to accomplish, chiefly because of the heavy weights involved in tank suspensions. By October 1943 synthetic rubber was approved for the bogies of light tanks and half-tracks, and, beginning in January 1944, one fourth of the bogies for the medium tank were made of synthetic rubber. But by the spring of 1945 the bogie of the heavy tank T26E3 had not yet been converted to synthetic rubber.89

Truck Tires

Transfer to Ordnance of responsibility for motor transport vehicles in August 1942 opened an entirely new phase of the Ordnance rubber conservation program. Thereafter approximately 65 percent of the Ordnance rubber allotment went into pneumatic tires and tubes, as compared with only 35 percent used in tanks, mechanical rubber items, and self-sealing fuel tanks. When the Tank-Automotive Center was established at Detroit in September 1942, a Rubber Branch headed by Col. Joseph M. Colby, and later by Lt. Col. Burton J. Lemon, was made an integral part of the new headquarters.

Conversion of pneumatic tires from natural to synthetic rubber was a gradual process which began with the small tires, moved on to the mediums, and ended with the large tires only partially converted at the end of the war. The changeover had to be geared both to the gradually increasing supply of synthetic rubber and to the results of tests under field conditions. There was no easy short-cut to the production of good synthetic military tires, no

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Chart 18: Monthly average 
use of synthetic rubber by the Ordnance Department: 4th quarter, 1942; 3rd quarter, 1943

Chart 18: Monthly average use of synthetic rubber by the Ordnance Department: 4th quarter, 1942; 3rd quarter, 1943

Source: Quarterly Review (December 1943), Chart 25

way to solve the problem except through the painstaking trial-and-error process of building and testing tires by the thousands. The highways and country roads adjacent to Aberdeen Proving Ground provided a permanent testing ground on which the rubber components of tanks, trucks, and amphibian vehicles were tried out. At Camp Shilo, Manitoba, in the winter of 1942–43, and on the Alaska Highway during the winter of 1943–44, Aberdeen detachments conducted tests of synthetic rubber products in snow and ice and subzero temperatures. The Army Desert Test Command at Camp Seeley, California, established in March 1942, conducted endurance tests in extremely high temperatures over miles of hot, dry terrain. The most extensive tire-testing operation of this kind was carried on under Ordnance auspices at Normoyle Field in Texas where from 200 to 300 vehicles ran for 24 hours a day, 7 days a week, over a 165-mile test course, completing 22,000,000 vehicle test miles by June 1945.

In the Army’s small-tire group the most important tire was the 6.00-16 for ¼-ton jeeps and passenger cars. The first tests of this tire with synthetic tread on a natural rubber carcass in 1942 were so promising that new tests were conducted with tires made entirely of synthetic rubber. These tires performed so well, most of them running twice the required mileage, that the Ordnance Technical Committee approved their procurement in December 1942. Before conversion to synthetic rubber, each 6,00-16 tire required 10 pounds of natural

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rubber and nearly 6 pounds of reclaimed rubber; after conversion, only 4 ounces of natural rubber and 2 pounds of reclaimed rubber went into each tire. By June 1943 the use of synthetic rubber was extended to all tires in the small-tire group.90

Of the three size groups of Army tires, by far the most important, in terms of rubber conservation, was the medium-size group, including tires from seven to ten inches wide. Nearly three fourths of all the rubber used for Ordnance tires went into these sizes, which were used on trucks of all weights up to six tons. In contrast to the quick and relatively easy conversion of the smaller tires, the use of synthetic rubber in medium-size tires presented many difficult problems. Because these tires had thick sidewalls and carried heavy loads, they ran at high temperatures, which weakened both the rubber and the tire cord. A partial solution to this problem was found in the use of rayon cord, which stood up much better under high temperatures than did cotton cord. Tires made with rayon cord required fewer plies and therefore less rubber than did cotton-cord tires, and tests demonstrated that, in the medium-size tire group, synthetic tires made with rayon gave nearly as good service as did natural rubber tires.91 The only difficulty lay in the shortage of the particular kind of rayon needed. In spite of rapid expansion of rayon cord production facilities, through the efforts of the War Production Board, there was enough rayon cord only for the 9.00-20 and larger tires in which cotton was totally unsatisfactory. For the other sizes, reinforcing cotton plies known as “cap plies” had to be placed over the regular plies to give added strength. As a result of these and other efforts, the production of all medium-size tires with 35 percent synthetic content—synthetic tread on natural rubber carcass—was approved by the Ordnance Technical Committee in June 1943, and a month later the percentage of synthetic was doubled. For medium-size tires with highway tread this percentage remained at 70 for the rest of the war, but in October 1943 the percentage of synthetic rubber authorized for medium-size tires with mud and snow tread was raised to 90, and later to 92.92

Conversion of large-size tires to synthetic rubber was delayed for three main reasons: it was difficult to make them of synthetic rubber; the military requirement for large tires was comparatively small until the end of 1943; and the smaller tires used practically all the available synthetic rubber. During the winter of 1943–44 extensive tests were made of large tires in sizes from 11.00-20 to 13.00-24 made of 70 percent synthetic rubber with rayon instead of cotton cord. The results led the Ordnance Technical Committee to give its approval to these tires in April 1944. The 14.00-inch truck and trailer tires were not made with synthetic rubber except for the 14.00-20 tire with mud and snow tread, for which 35 percent synthetic rubber was approved in the spring of 1945.

Conversion to synthetic rubber was by no means complete at the end of the war. In many items natural rubber still had to be used if performance was not to be

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Table 14—Summary of conversions to synthetic rubber by V-J day

Product Percent Synthetic Markings on Sidewalls
Tires:
5.50 through 7.00, 8-ply 100 S-3
7.50-20 and 9.00-16 93 S-8
9.00 and 10.00 (10-ply and up) 90 S-4
11.00 through 13.00 70 S-6
14.00-20, 12-ply 70 S-6
14.00-20, 20-ply 35 S-7
14.00-24 5-10 S-11
Combat tires:
6.00-16 100 S-3
8.00-16 90 S-4
8.25 and 9.00 70 S-6
14.00-20 5-10 S-11
Tubes 100 Blue stripe
Flaps 100 Red stripe
Tank track blocks 100 Red rectangle
Tank track bushings crude rubber
Bogie tires, 20x9x16 crude rubber
Bogie tires, other size 100 Red rectangle
Band tracks 70 Red medallion

Source: Ordnance Digest, 27, 9 (September, 1945), 10, OHF.

seriously impaired. In addition to use in large-size. tires, small quantities of natural rubber were used in all tires as an adhesive between tread and carcass, and in scores of very small items, such as the cores of tire valves and tire gauges, natural rubber was essential. By the summer of 1945, 86 percent of all Ordnance tire production had been converted to synthetic rubber, and conversion of mechanical rubber items to synthetic construction was over 95 percent complete. The more difficult conversion of tank tracks and bogies stood at 65 percent. Efforts continued during the summer of 1945 to curtail the use of natural rubber in Ordnance items, but everyone recognized that the worst of the rubber crisis was over. “Primarily owing to the Ordnance Department’s program,” the Ordnance Research and Development Service reported, “the total of crude rubber required by the industry for mixing with … synthetic was only 10,000 tons per month in 1945, a rate that equalled imports. The Ordnance Department required about 2500 tons per month, a figure far below its proportionate share of the consumption before conversion and one indicating the success of the Ordnance program.”93

Preservative Materials

Closely allied to the Ordnance conservation program was the effort to preserve finished items of equipment by the use of rust-preventive and corrosion-preventive coatings and the employment of advanced packaging methods to save shipping space

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and prevent damage from rough handling. The waste of material resulting from breakage or from corrosion was just as real as the waste resulting from improper use of critical materials in the original design. It was, in some respects, even worse. “If, for any reason,” an Ordnance report stated, “matériel arrived in an overseas theater in unusable condition due to improper packaging, ... it represented a loss of the raw materials from which it was manufactured, a loss of man-hours which were required to process and move it, a loss of packaging materials, a loss of space in trucks, depots, railroad cars and ships—in short, so much loss that it would have been far better if the item had never been made.”94 And, of course, the morale of combat troops suffered when unserviceable ammunition or equipment was received.

At the outset of World War II the methods and materials used for preserving and packaging Ordnance matériel were little more advanced than they were at the close of World War I. No special consideration had been given to the problem of developing preservative materials during the 1920s and 1930s because War Department plans in those years did not envisage the shipment of vast quantities of military equipment to widely scattered overseas battlefronts. Contracts with manufacturers ordinarily called for no higher standards of packaging for military supplies than those prescribed by common carriers for shipment of commercial goods at the lowest applicable freight rates.95 These packaging methods had proved reasonably satisfactory for normal shipments of commercial material in time of peace, but they proved wholly inadequate for the shipment of military equipment in time of war. Packaging materials and preservatives in World War II not only had to protect matériel against a wide variety of climatic conditions, from subzero temperatures in Alaska to steaming jungles in the South Pacific, but they also had to guarantee that equipment would arrive in serviceable condition after it had made a long sea voyage, been exposed to rain, corrosive salt spray, and abrupt changes in temperature, and been landed with primitive equipment at a bombed-out port or newly won beachhead.

Although responsibility for the development of packaging methods for Ordnance matériel rested with Field Service during the early months of the war and was then transferred to Industrial Service, the Research and Development Service played an important role in developing the preservatives needed to prevent rust, corrosion, and fungus growth.96 An industrial packaging expert, Mr. Neil A. Fowler, was engaged early in 1942 to serve as a consultant to General Barnes on packaging and preserving Ordnance matériel, and later Dr. G. A. Greathouse of the Department of Agriculture was employed to study means of protecting matériel from damage by mold. The Materials Branch gave its attention primarily to protection against fungi and to the development of preservative greases, oils, and paints, while Field

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Service and Industrial Service, working in close cooperation with industry and the Forest Products Laboratory of the Department of Agriculture, developed protective wrapping materials and devised improved methods of using the materials in packing and crating Ordnance supplies. These measures furthered the Ordnance conservation program by preventing waste all along the supply lines which stretched for thousands of miles from factories to fighting fronts.

The essence of the problem facing the Materials Branch was that most Ordnance matériel, being made of metal, was subject to rust or corrosion when it became wet or dirty. Even minute quantities of water, dirt, or salt spray could work havoc. The moisture in the air within a package, if it condensed on metal parts when the temperature dropped suddenly, could cause rust; the moisture in a man’s fingerprint was capable of causing rust on an exposed metal part. The solution to the problem, although difficult to achieve, was clear enough: matériel had to be kept clean and bone dry either by enclosing it in moisture-proof packages or by covering it with a protective coating such as paint, oil, grease, or a plating material. The search for, and standardization of, such protective coatings and wrapping materials for Ordnance matériel became vitally important during World War II.

Painting and Plating

Two of the most widely used methods of protecting Ordnance matériel against rust and corrosion before the war were painting and plating. Wherever practicable, exposed parts were given a coat of paint that served the dual purpose of protecting the finish and providing camouflage coloring. Parts for which paint was not suitable, and for which permanent protection was needed, were plated with such metals as zinc, cadmium, nickel, or chromium. When the outbreak of war brought an acute shortage of plating materials, Ordnance was forced to adopt a thinner plating on many items and to eliminate plating altogether on others. At the same time, while paint itself was rapidly becoming a scarce material, experience in overseas operations revealed that many of the paints used in 1941 did not provide adequate protection for military equipment, Ordnance, as the custodian of Army paint specifications, therefore undertook a program to conserve paint, standardize military paints, and develop paints with better protective qualities.97

Late in 1942, as reports came in of excessive corrosion of the metal boxes in which small arms ammunition was packed, the Materials Branch started work on developing a rust-inhibiting paint for these containers to replace the lusterless olive-drab paint originally adopted primarily for camouflage purposes. Modifications made in a one-coat paint used by the Engineer Board on aircraft landing mats produced a remarkably effective semigloss paint for ammunition containers. Its use was soon extended to a wide variety of other containers. Later, when hermetically sealed boxes were adopted for small arms ammunition, the method of packing and painting these boxes required a quick-drying paint. Industrial chemists promptly developed a paint that permitted painting, stencilling, and packaging the container within twenty minutes. At the same time, intensive efforts were made to provide a

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suitable protective finish for steel cartridge cases under development during 1942 and 1943.

Oils, Greases, Plastics

Not all classes of Ordnance items could be protected by paint. Many had to be coated with oil or grease and enclosed in a protective wrapper while in storage and transit. Aircraft machine guns fell into this category, and the effort to develop suitable preservative materials for them may be cited as a typical example of the work of the Materials Branch. At the start of World War II the Ordnance Department was still using a heavy grease, popularly known as cosmoline, to rustproof such weapons. It gave excellent results, but it was hard to remove. When weapons coated with this compound arrived overseas they had to be given a thorough cleaning or “degreasing” before they were fit to use, and if even a small portion of the grease were left on the weapon, it might fail to function in extremely low temperatures. In 1942 Ordnance engineers, working in close cooperation with a machine gun manufacturer, discarded the heavy grease in favor of a light preservative oil that would lubricate working parts satisfactorily and provide a certain amount of protection against rust. To supplement the action of this protective oil, a wrapping material was needed that would be not only waterproof but also moisture-vapor-proof. Experience had shown that in damp weather the moisture in the air was able to pass through most waterproof materials and then condense on the metal parts within the package. After extensive experiments a material was found that was moisture-vaporproof, flexible, tough, and transparent. But, when tests were made on weapons coated with oil and enclosed in the moisture-vaporproof material, the weapons still rusted. The explanation lay in the condensation of moisture from the air trapped within the package and within the gun itself. The problem was solved by placing a dehydrating agent within the package to absorb the moisture before it did any harm. “In the past two years,” the Small Arms Division reported in June 1945, “not a single case of a rusted machine gun packaged in this manner has been reported.”98

In the fall of 1943 a new type of material was adopted for protecting Ordnance parts and assemblies of moderate size and weight. This was a thermoplastic material composed of oils, waxes, and ethyl-cellulose which, after application to the item by a hot-dip bath, formed a tough elastic coating that not only gave good protection against corrosion but could be quickly removed by slitting and peeling.99 For many types of parts, use of this strippable coating was more economical than the light oil in a moisture-vaporproof wrap. In 1945 it was estimated that Ordnance installations and contractor plants were using the new compound at the rate of 150,000 pounds a month.100 Another strippable compound, attracting wide attention in the spring of 1945 but not adopted before the end of the war, was a cellulose-acetate-butyrate-base material that had the advantages over the ethyl-cellulose compound of being fairly transparent, applicable at lower temperatures, and more easily stripped from recesses. Further studies, in which Ordnance cooperated with other branches of the service, were begun in the fall of 1944 on

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a spray-type strippable compound developed by the Navy for long-time storage of all types of war matériel and production equipment.

Automotive Matériel

The preservation of automotive matériel, including tanks, trucks, and spare parts, was one of the most important phases of the Ordnance program and was one of infinite complexity. Late in 1942 when the problem was referred to the SAE War Engineering Board for study, the board appointed numerous subcommittees to deal with the preservation of such items as engines, cooling systems, batteries, and service parts, and to recommend cleaning methods, corrosion-prevention compounds, and packaging materials. As the subcommittee recommendations were received, tested, and approved they were incorporated into the appropriate Ordnance specifications or packaging regulations.101 One of the most successful developments in this field was the application of alkyd resin varnishes to the electrical systems of vehicles to prevent them from “drowning out” after exposure to heavy rains or submersion in water. Tank hulls were prepared for shipment in the same way as aircraft machine guns—a moisture-proof and vaporproof wrap enclosing a dehydrating substance. Less successful was the effort to develop an exterior paint for automotive vehicles. Before the war, lusterless enamel was specified for this purpose largely because of its camouflage value, but it was too porous to give adequate protection in areas of extreme humidity and heavy rainfall. Because the paint shortage precluded using two coats—the semigloss covered with the lusterless—the Ordnance Department recommended that, in spite of the sacrifice of camouflage protection, semigloss enamel be adopted for all vehicles. This recommendation was not finally approved by higher authority until very near the end of the war.102

Perhaps the most unusual problem of matériel preservation that Ordnance faced during World War II was the rapid deterioration of equipment caused by mold or mildew in extremely hot and humid areas. It was not a new problem by any means, but it had never before assumed such large proportions as in 1944 when fighting started on a large scale in the South Pacific. Supplies deteriorated at an alarming rate. Textiles rotted and fell apart; cork and paper gaskets disintegrated; leather holsters and instrument cases became covered with fungi that caused the threads to break; electrical instruments failed because fungus growth on the fabric-sheathed wires caused short circuits. The Materials Branch began studying methods of protecting equipment against mold early in 1944 and in April of that year published a pamphlet on the subject.103 In September 1944 an Artillery Tropicalization Mission was sent to the Panama Canal Department to investigate measures used in that area to prevent deterioration of Ordnance matériel by mold. With the aid of industry and other branches of the Army, Ordnance soon developed means of controlling mold on a wide variety of items and issued several of the early Army specifications in this field. A varnish containing a fungicide

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proved effective in controlling mold on electrical equipment and gaskets. For leather items, neat’s-foot oil mixed with a fungicide gave excellent protection. Gun covers, tarpaulins, vehicle tops, and cotton cordage were protected by the use of copper naphthenate as a fungicide. Difficulties were experienced with some items. For example, the fungicide used on wooden ammunition boxes caused dermatitis, but the fungus problem was generally well under control by the spring of 1945.104

The successful efforts of the Materials Branch to develop effective preservatives provided a fitting supplement to its efforts to promote the conservation of strategic materials in the design and manufacture of Ordnance items. It constituted the “follow through” that was essential to the safe arrival of supplies in the theaters of operations. It sharply reduced some of the appalling losses of equipment that occurred early in the war, and entirely eliminated others. When combined with the extensive efforts of the Field Service and the Industrial Service in developing and applying advanced packing methods it contributed in very large measure to the success of the Ordnance program to conserve strategic materials.