Some time ago I bought this M42 Relic.
After cleaning and rinsing of the rust came to my surprise a lot of debris and thick brown Cammo up like the pictures you see is a thick and brown paint mixed with sand (mud Cammo) looks like cement.
After some on the Wehrmacht Awards forum have I heard from a waf member that is was an Luftwaffe field helmet for ground combat troops, you can still see remnants of a Luftwaffe eagle circled in red.
Even on the inside of the helmet is the mud lubricated.
It is not rust, it is real a thik brown camo layer pasta.
All in all, I have a lot to do to clean up well and should beware of the Camo. Unfortunately the chin strap, it was broken up into 3 stukken but I have sewn back together. The interior is still firmly and in very good condition.