Hello,
I also have a preference for Ersatz, whatever they may be.
As far as the so-called pressed cardboard or papier-mâché helmets are concerned, you should know that in fact the principle of manufacture is identical with Vulkanfiber, Bakelite, Isorel, Melamine, etc....
In fact, it's a “composite” material, i.e. combining at least 2 components.
-1- The framework can be made from horticultural fibres, hemp, flax, cellulose, wood shavings or sawdust, etc...
-2- The binder can be natural glue, latex, resin etc...
The 2 components are mixed together, then pressed into a mould and heated. The binder agglomerates and hardens, then the mould is demoulded.
In the case of spiked helmets :
---When it comes to Vulkanfiber, the ‘sheet’ is thin (1.5mm) and very hard. (like plastic).
---When using pressed cardboard, the ‘sheet’ is thicker (3-4mm) and less hard. (like leather).
I'll take photos as soon as possible. I have at least one pressed cardboard helmet, and at least one Vulkanfiber helmet.
After 1950, fibreglass and synthetic ‘polymer’ resin replaced these ‘natural’ materials.
After 2000, carbon fibre took over, becoming ever more resistant.