Leather peak coating

[ErWeSa]

Perhaps I can contribute something to the riddle what the leather peaks were coated with.
Here is the/a recipe I found for leather coatings (only in German, sorry):



BenVK was on the right track, see here:

Custom made Feldmuetzen Alter Art, Crusher Caps!

and here (post # 23):

Black Alter Art Cap

The other, simpler possibility is: black lacquer/varnish. I used it for the leather peaks of the caps I make and it works quite well - depending on the brand. I think in later years this was used for coating the leather peaks, in earlier years the product from the recipe above. This would also explain the variety of looks of these peaks/visors.