This article is a follow-up to “WWII-era M1 Helmets: A Beginner’s Guide to Collecting” that appeared in the July 2015 issue of Military Trader. These articles intend to provide the new collector with a delineative, step-by-step process to determine the WWII vintage of the M1 helmet liner. The M1 helmet liners distinctive WWII manufacturing features will be described and dates approximating time of specification changes listed. Also, collectors will be alerted to post-WWII modifications due to specification changes that were applied to original WWII produced helmet liners
M1 HELMET LINER
The liner for the M1 helmet served as the suspension for the steel helmet. It acted as a cushion between the wearer’s head and the steel of the helmet. The liner also served as headwear for ceremonial and official duties where a steel helmet was not necessary, such as a parade, guard, and MP duty in non-combat areas.
WWII production M1 liners underwent many changes during the war, so let us start with what they had in common. All WWII liners had a button-in nape strap; a riveted, shoestring adjustment suspension; and a leather chinstrap. All other features of the liner were eventually improved or replaced out of necessity or economy.
THE FIBER LINER
The first M1 liners were manufactured of fiber (a material similar to cardboard) and covered in olive green twill cloth. Hawley Products, (a renown manufacturer of fiber sun helmets for both the US and Canadian militaries) and the General Fibre Company were chosen to manufacture the M1 fiber liner, Today, these liners are referred to by collectors as “Hawley liners.”
The distinctive features of Hawley liners were that they were lighter, possessed a thicker rolled rim, and a ribbed fabric textured exterior as opposed to paint or combination of paint and sand found on later liners. As can be expected, the fiber liner was not robust enough to handle the harsh treatment of combat. By late 1942, a new method of liner production was adopted for use.
HIGH- AND LOW-PRESSURE LINERS
As the weakness of the fiber liners was revealed, designers sought a new way of manufacturing a more robust liner. This resulted in the low- and high pressure liners.
Low- or high-pressure refers to the pressure applied during the production process involved in liner manufacturing. Both low- and high-pressure liners were the first to feature the front eyelet.
The low-pressure liners were intended to rapidly supply a more robust M1 liner until high-pressure liner manufacturing was able to sustain wartime production needs. These were manufactured from early 1942 to late 1943. Like the fiber liner, low-pressure liner bodies were found to be too fragile for Army requirements.
The most distinguishing features between the low- and high- pressure liners were the finish, texture of the interior, and the overall rigidness of the liner’s body. Low-pressure liner’s interior possessed a substantially dull and rougher finish than high-pressure liners, although St. Clair’s early production liners interior were painted.
Low-pressure liners were made exclusively by two companies: Saint Clair and Hood Rubber. Both used ink stamps to identify their liner production. St. Clair used either an “X” or “SC” in yellow ink and Hood rubber, “HR” in silver.
The low pressure liner’s bodies were prone to cracking, especially around the bottom edges of the liner. The fragile nature and short production-life of less than two years during the early part of WWII make low-pressure liners significantly harder to find in serviceable condition than high-pressure liners.
HIGH PRESSURE LINERS
Production of low- and high-pressure liners overlapped during 1943 and both can be found with rayon or cotton suspensions, fixed or replaceable chin straps. High-pressure liners were manufactured by seven of the eleven WWII liner manufacturers: Westinghouse, Inland, Firestone Tire and Rubber, MSA (Mine Safety Appliances), Seaman Paper, CAPAC, and (IMP) International Molded Plastics.
Eventually, by 1943, both types of liners were equipped with cotton suspensions and chin strap posts for the new, replaceable chin strap. The interiors had glossy or polished finishes (in comparison to the low-pressure liner).
High-pressure liner bodies were more robust than low pressure liner bodies and had a feel similar to hardened flexible plastic. This made them more durable and is the reason the high- pressure liner superseded the low-pressure production method.
High-pressure liner production lasted from 1942 to 1945 when all contracts were cancelled—until the start of the Korean War in 1951.
M1 LINER SUSPENSION
The suspension, together with the headband and nape strap, located at the lower rear at the back of the liner below the headband, supported the weight on the wearer’s head and neck. The suspension and nape strap used in the first production model of (fiber) liner was made from white rayon. It had an adjustment string in the center holding the suspension straps together. This headband had six pairs of unpainted steel female snaps for the attachment of a non-adjustable sweatband and two pairs of snaps for the nape strap.
In late 1942, a new suspension was developed. It differed from the rayon model by the change of material to olive drab number three cotton webbing and the deletion of the snaps for the non-adjustable sweatband. The nape strap suspension retained the two pairs of female snaps for the nape strap (this continued into the 1960s).
The rayon headband and nape strap was installed on early low- and high-pressure liners. Despite a specification for webbing color change to olive drab number seven (dark olive drab) in 1943, the suspension retained the olive drab number three (khaki/green) shade throughout the war.
The rayon suspensions installed in the first production liners and early production low- and high-pressure liners were secured by six unpainted steel rectangular washers. Three washers also held the nape strap suspension.
With the adoption of the cotton web suspension in late 1942 washer shape was changed to unpainted, A-shaped washers. In 1943, the green-painted A-washers replaced the earlier unpainted washers during the manufacturing process.
The final WWII specification change took place in 1944. It allowed for the use of black-finished brass “A” washers. That same year, the snaps for the installation of the nape strap were changed from unpainted steel (1941-1944) to blackened brass.
The headband attaches to the liner suspension and exists to ensure a proper and comfortable fit around the wearers head. The first pattern headband was made of rayon and attached to the rayon suspension by six unpainted, male snaps. It was not adjustable, requiring supply channels to stock up to thirteen sizes of headbands. This headband was partially lined with leather in the forehead area.
The adjustable cotton web headband that replaced the rayon non-adjustable headband after the summer of 1942 reduced the number of sizes to three. They were fully lined with leather except in the rear, where, initially, a double wire ring adjustment was placed. This was replaced in the same year by a single friction buckle painted green. In 1944, specifications allowed for the use of blackened brass in buckle production.
All cotton web headbands attached to the suspension by six spring clips which were painted green. The nape strap cradles the back, or nape, of the neck. The nape strap was originally white rayon and supplied in five sizes. The later cotton variant reduced the number of sizes down to three. The method of attaching the cotton web nape strap by four button snaps remained unchanged into the 1960s. Initially, these were unpainted,but were changed to blackened brass in 1944.
The leather chin strap on the first liners from 1941 to late 1942 were attached by unpainted, riveted attaching loops and were adjusted by a small blackened ladder buckle. The chinstrap loops on the left and the buckle on the right were secured to the leather strap by eyelets that were painted brown.
In late-1942, the chin strap underwent major fabrication/specification changes. The new chin strap was replaceable via two triangular clips at either end which attached to posts located inside the right and left sides of the liner. Originally painted green, by 1944 they were finished black. The brown painted eyelets used to secure the ends of the first pattern chinstrap were replaced on all clip in chin straps by green painted rivets.
In late 1942 the buckle was replaced with a green-painted steel wedge shaped clamp with a flat leaf. The buckle was changed in 1943 to a clamp with a more pronounced lip to ease adjustment of the buckles clamp. In 1944, the buckle and clip composition was changed to either blackened brass or steel.
One of the easiest liners to recognize as WWII, is to look for the fabric-covered exterior of a fiber liner and/or turn it over and look for the white rayon or olive drab number three webbing suspension. Start your evaluation from there.
The most immediate post-war developments were instituted prior to the Korean War. Whereas changes to the M1 helmet dealt mostly with the exterior, e.g., paint color and aggregate and chin straps, the liner’s specification changes tended to influence its interior. Some of these changes included a dark olive drab number seven suspension,a return to steel “A” washers painted green in the early 1950s, and then to black painted steel and wide spread use of the adjustable nape strap first adopted in 1945.
Like the M1 helmet, if a WWII-era liner has post war parts, e.g., headband or nape strap, or chin straps they would need to be replaced to accurately represent a WWII liner. But unlike the helmet, this is much easier and does not require specialized tool, unless replacement of the suspension or repainting is needed..
If replacement is necessary or desired, extra care must be exercised as buttons on liners suspensions can tear or be pulled out easily when removing or applying nape straps. The headband clips have teeth and must be gently removed to prevent tearing of the suspension fabric. Movement of clamps and buckles also should be done slowly. Never jerk or yank any part of the liner—damage is almost a definite result. If you find yourself frustrated at any point just put it down and walk away. While frustration will resolve itself, damage done to a seventy plus year old piece of history is permanent.
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