In 2017 I was metaldetecting a ww2 Battlefield with 6 friends. During this trip we found many items and relics, but the most fantastic find were two German helmets lying next to eachother about 1 meter in the ground! The helmets were very much rusted but still had their liners and kinstraps (nicely rolled insiede the helmet).

For more than 2 years(!) these helmets lay by my friends at home and at work, before one was lended to me (instead of a museum). I started researching how to best clean such an helmet, since the rust seemed thick, but loose. Thats how I used oxalic acid. And the helmet gave a very new insight...... it showed the original grey paint but also a light brown sand color camouflage pattern! Also marks of the left hand wehrmacht badge could be seen! 

In the area we were searching small groups of Normandy surviving German soldiers fought together with Fallschirmjager. No doubt this helmet belonged to a Normandy survivor - thats the place were German soldiers camouflaged their own helmets in all kind of manners.

I also bought a high quality repro M1942 Steel Helmet (same model as the one we found) and painted it with the same camouflage pattern and color. This way an almost exact model can be viewed for reference:

Another superb finding was a steel version Luftwaffe belt buckle - in an area were Fallschirmjager took a last stand. I used oxalic acid to clean the rust of the buckle.

A fragment which took some time to determin it: a fragment from a German gass mask canister lid. The original green paint is still visible, the shape was perfect round, some fabricated punches are also visible, the outer rim is hollow with wire inside of it and a small piede of hinge is still attached. The thickness of the plate is also exactly the same.