Many World War II German helmets have been discovered over the past 70 years. Many helmets are found to be covered in rust, broken into pieces or missing emblems and paint. German "relic" helmets have been found and removed from battlefields, abandoned bunkers and even from old burial grounds. Years of rust build-up may reduce the value of a "relic" helmet, but with the proper removal of rust it may help to restore the helmet and also help to increase its value.
Fill a plastic container, large enough to submerge the helmet in, with warm water and a small amount of mild hand soap.
Place the helmet into the container, gently, so that it is completely submerged. It should soak for about two hours.
Remove the helmet, gently, from the water and rinse it with clean warm water.
Scrape the helmet all over with a wire brush, gently, to remove any loose rust.
Rinse the helmet in warm water again and use a blow dryer, set on warm heat, to speed up the drying process.
Dip the applicator brush into the naval jelly jar, wearing rubber gloves, and apply the jelly all over to completely cover the helmet.
Lay the helmet onto the newspaper and let it sit for five to 10 minutes. Do not exceed 15 minutes.
Rinse the helmet with warm water to remove the naval jelly and use a towel and blow dryer to dry the helmet completely.
Place the helmet into a clear plastic bag for safe storage from humidity. You can use an oil-based paint to protect the helmet, but be aware that this may reduce the value of the helmet.
Naval jelly may remove paint and/or damage the helmet if left on more than 15 minutes.