Found this aluminum token in a S.F. park last Saturday. Unable to identify due to its horrible condition. Anyone have any ideas? I believe our acidic soils in the Bay Area really doesn't like aluminum?
Yep - Al + O2 = AlO2 which occupies more volume than plain aluminum, hence the blows. Not much you really can do about it. The piece pictured is from the 1939 World Fair in San Francisco where the Union Pacific Railroad had an exhibit and gave these out as souvenirs.
John in ID
I prefer to use Naval Jelly on the Aluminum.. it will remove the rust... leaves holes were the rust was but leaves the Aluminum intact.. have to use it repeatedly... can leave the Jelly on the coin for about 20 minutes.. then remove with a old toothbrush... repeat until the black spots are gone.