I just wanted to issue a warning to my fellow collectors regarding the use of this product on M15 haube fittings. You MUST be VERY CAREFUL in using this to remove rust on the M 15 metal. I recommend timing the length of immersion and watching very carefully during the process. In my case 2 hours did the job on one item (wappen) and 1 hour on the other..part of a spine. Total rust removal did not happen on these pieces as I was worried about damage but I am satisfied with the results. Evaporust does change the patina/colour of the fitting. Now whether this is due to removal of oxidization after 100 years or an actual effect on the original finish, I don't know. There are different finishes/paints (?) found on the M15 helmets and this product does have an effect. I was also told by my friend Tony Schnurr to use gun oil on this after use so as to prevent rust from returning to the cleaned areas. I will be following this advice. In conclusion, I would only use this on an exceptionally rusted M 15 fitting. If things were not that bad, then I would not take the chance involved. I would use Evaporust on a steel JzP or Kurassier helmet shell as there would be no effect on the metal except rust removal. This can not be said for the wappen, spike or M 91 side posts on such helmets.