Nice! Re. your copper comments, you might investigate: https://www.nps.gov/museum/publications/conserveogram/cons_toc.html#collectionpreservation
for appropriate treatments, or
(in the latter, see 5% oxalic acid mixture but I would suggest trying it without pumice powder). I would definitely test a tiny area first, using the gentlest means possible (little pressure and a Q-Tip?). I seem to recall that oxalic acid is the main ingredient in certain cleaners; you might find something you could use readily available at a local Alaska hardware store by Googling.