OK Vlad Your Leninets camera was made in the same process. You can see that when the years go on the surface becomes dull, and become hard to see the fine deail. This should happen with Parkinson camera if the surface is not protected. Protection should be made with colorless Nitro-cellulose enamel. I have done so in a bronze lustre in my home in 1969 and it is absolutely perfect up to day. In 1989 I built a Daguerreotype camera replica
http://www.novacon.com.br/abopics.htmIts emblem which was copy of the Michel's Auer original daguerreotype camera was done by the same (or similar) process. If you want I shall post new pictures of the camera that is still now in perfect condition. this technique provides beautiful results.
regards LP