Pub Talk - Are Plastic Liners Really Made From Plastic?

Hey gang, Big Red here at me favorite waterin hole, Cohan's Pub.

Pull up a chair, have a pint....

Here are two questions collectors often bring up while we’re enjoying a cold one at the pub:

Was the M-1 plastic liner really made of plastic? 

and

Why didn’t the Army just match the MSA Skullguard?

Let's get into it….

The short answers are, yes, the M-1 plastic helmet liner from WWII is indeed made of plastic, and regarding the MSA Skullguard, well, the devil is in the details.

Two specific factors contribute to the confusion with WWII M-1 liners, the first being what plastic looked like in its early developmental stage as compared to what we know as plastic in the modern day, and the second being the visible fabric pattern of the duck cloth used in the liner’s construction.

Visualize a construction crew making a concrete bridge or road. While the actual bridge or road is constructed from concrete, can you envision a framework of metal bars protruding from sections during construction? Well, that framework of steel bars is known as reinforcing bar, or rebar, and it is added to concrete structures to increase the strength of that bridge or road under tension.

In the case of the helmet liner, picture in your mind that the plastic phenolic resin is transparent concrete and the metal rebar is strips of cotton duck cloth. The duck cloth provides form and strength under tension while allowing the liner body to remain relatively light compared to the amount of unreinforced plastic that would have been required to achieve the same strength standards.

What exactly is duck cloth? Duck cloth is a heavy, plain-woven cotton fabric that holds up to heavy outdoor use without tearing or wearing through easily. The name comes from the Dutch word for cloth, “doek,” and was a common fabric and canvas weave favored by the Army for use in items like tents, tarps, sandbags, jackets, and the like.

Although the plastics industry was still in its infancy, several recipes for plastic-impregnated paper fiber or cloth were being used to make products for the civilian market at the time, and the Army wanted something similar for the new liner. In early 1941, the Office of The Quartermaster General invited several companies that made these products to submit samples of a liner made from whatever resin and reinforcing material they felt would get the job done. In mid-1941, the Standardization Branch of the Office of The Quartermaster General selected phenolic resin-impregnated cotton duck cloth as the best option for use in the manufacture of the liner they wanted.

One of these early participants was the Mine Safety Appliance Company, who undoubtedly received an invitation due to the safety helmets they sold to the civilian market. In 1941, the MSA Skullgard was the closest existing civilian product that resembled what the Army was after. Many collectors visually compare a Skullgard to a high-pressure liner and wonder why there was so much hubbub over the liner, suggesting that MSA could simply produce them.

While these MSA helmets functioned excellently as standalone safety hats for civilian uses, direct translation into a liner for the M-1 helmet would result in a shell that was too thick, heavy, and brittle for the Army's needs. However, along with the Quartermaster’s list of requirements, the manufacturing process for these helmets was the logical place to begin the pursuit of an acceptable liner.

The records I have been able to uncover are vague, but they clearly indicate that the original Skullgard was made from duck cloth impregnated with a resin recipe known as Bakelite. These same records also clearly indicate that the twin sister to the miner’s or workman’s Skullgard helmet, the Fireman’s Topgard helmet, was also originally made with Bakelite before MSA transitioned to a new, improved recipe for reinforced molded plastic developed by Westinghouse called Micarta, and although I was unable to uncover a similar document for the Skullgard helmet, I believe this same transition is a reasonable assumption.

Interestingly, both MSA historical records and Mark A. Reynosa, author of  The M-1 Helmet: A History of the U.S. M-1 Helmet in World War II, describe Westinghouse as a primary contractor for these Micarta shells, and although the references are not 100% clear, they infer that Westinghouse may have in fact molded the shells for these helmets under contract to MSA, who, upon receipt of the shells, only assembled and finished them.

This inference seems to line up nicely with quartermaster records, which explain that Westinghouse, with over 20 years’ experience manufacturing molded plastic products, was specifically desired by the Army as a participant in the beginning liner development process. To get things moving toward the goal of a plastic liner, the Office of The Quartermaster General had chosen to rely on the practical experiences of the companies within the plastics industry to develop and produce sample liner bodies based on their best solutions. The problem was that the first experimental contract did not include reimbursement for the costs of creating the steel molds needed to form the shells; although Westinghouse had provided samples of their Micarta-impregnated cloth for testing by the Army, they opted out of the program.

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Seriously, Westinghouse dropped out because they would have to pay for their own molds, you say. Well, before judging them too harshly, my friend, remember that the Kellering process for molds cost upwards of $2,500.00 per set in 1941 dollars, or $54,387.59 in modern dollars, which is a pretty significant investment on an experimental contract without a confirmed return on investment. If you would like to know more, check out my blog on “The Price of Plastic - Financing Liner Manufacturers”.

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To the enormous surprise of nobody involved, the Standardization Branch chose Micarta as the most suitable option for molding the liner the Army desired. This is why, shortly after December 7, 1941, the Quartermaster adjusted their compensation for suppliers in the liner program and formally insisted that Westinghouse rejoin the development program.

Can you name the one plastic liner manufacturer who delivered liners to the Army that did not use cotton duck cloth in the manufacture of their liners?

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If you have been following along with us in our series on the development of the new M-1 plastic liner, you know the rest of the story and you know this road was lined with all kinds of trials and tribulations; however, through trial and error and several rounds of hard knocks, the diligent hard work and cooperation between the Army and their industry partners successfully mass-produced this new liner in an astonishingly short period of time, revolutionizing both the plastics industry and the design of military head protection for generations to come.

Answer:

Did you answer Hood Rubber, Then your smarter than the av-er-age bear!

Hood Rubber Company used 4-ounce high-count cotton sheeting cut into strips 2 inches and ¾ inches wide in the construction of their liner’s body.