Obstacles to Production II -- Plastic Liner Procurement IV

Did you know that liner firms selected such an incredibly diverse range of options for the resin, cloth, and assembly of their pre-forms that the resulting fallout of problems became the second largest bottleneck to the manufacture of the new plastic liner?

Plastic Impregnated Duck Cloth:

In mid-1941, the Office of the Quartermaster General (OQMG) extended invitations to multiple firms to produce and submit samples of materials plasticized in the formula of their choice for the Army to review and choose the materials and resin recipe they felt would best meet requirements for a plastic liner for use in the new M-1 helmet. In late November, the Standardization Branch of the Office of The Quartermaster General (SBOQMG) selected phenolic resin reinforced with lightweight duck cloth as the best choice.

Duck cloth is a weave of fabric favored for its outdoor durability in the form of clothing, tents, tarps, sandbags, and many other war-related applications. In 1940, as the Army prepared for war, the Quartermaster began acquiring all manner of duck cloth and stockpiling it at the Jeffersonville Quartermaster Depot. Access to this fabric was placed under limited restriction use by the War Production Board and allocated by the QMC to firms upon need and request, giving preference to firms based on their priority certification.

The OQMG did not anticipate any unusual problems concerning phenolic resin-impregnated duck cloth and thanks to the stocks retained at the Jeffersonville Depot, prime contractors never experienced a shortage; however, the standard low-priority A-1-i certification assigned to Quartermaster items once again hindered them from obtaining the quantities they needed to meet either their contract obligations or the desired due dates. Although the lack of top priority certification caused time delays, the real culprit behind resin cloth issues was the direct result of the decision to encourage early production by foregoing any meaningful experimentation or implementation of standards for the molding process.

As they did with molds, the Standardization Branch of the Office of The Quartermaster General (SBOQMG) advised single-sourcing the resin cloth to guarantee uniformity and quality, which, like mold-making, was a recommendation not followed. Each firm having the freedom to make their own molds led to a variety of material selections, some opting for solid steel castings while others chose porous or iron castings. The result of this decision then required the selection of specific resin cloth attributes that would perform best within their chosen mold cavities. Some firms used a standard 8-ounce duck, some used 10 or 12 ounces, and others opted to have custom-weight cloth made to best fit their process, the only overarching requirement being that after cure, the chosen process must result in a desirable liner.

With the independence of decision-making granted to firms by the OQMG, liner pre-forms, like mold-making and resin cloth selection, varied by company as to the approach used to their fabrication and assembly. Each firm used its own inventiveness to determine the die-cut shapes used for their liner body sections, as well as any reinforcing patches applied to the sides or crown. As it turned out, the confidence and freedoms afforded to liner firms by the OQMG proved to be a miscalculation, as these firms approached the new liner as if it were a normal commercial product on an assembly line.

As manufacturing got under way, firms turned out acceptable liners next to ones with all manner of defects, from blisters to cracks, pinholes, wrinkles, and corrugated edges. Investigations into this matter revealed that not only variances in the duck cloth, resin formula, and saturation levels were causing issues, but also revealed that the arbitrary assembly of pre-forms or the way in which they were placed inside the mold cavity could result in unexpected outcomes.

The Chicago Quartermaster Depot (CQMD) moved quickly to address all the issues that presented themselves during these initial attempts to begin production. Regrettably, having allowed every firm to choose their own mold material, die-cut shapes, pre-form assembly, fabric weight, and resin saturation now meant that troubleshooting would not be easy, and there would be no simple stock answers. At this point, the only sure path to guarantee a foolproof cure at the end of each molding process would be to halt production and experiment with each individual process until acceptable and repeatable solutions could be found. 

  Now you know….

Did you know:                                                                                                    

Every liner firm purchased phenolic resin-impregnated duck cloth from an outside vendor, the exception being Westinghouse, who made their own resin and impregnated their own duck cloth on site.

Remember. 

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