A Dirty Mainspring

Here are some before, and an after image of a mainspring from a 6 size Seth Thomas pocket watch.

This is one of these watches that does not appear to have been opened up in several decades, and in these cases it takes some extra work to get the parts clean. Old organic watch oil, made from sea animals, turns green and almost solid. There is certain stale, vaguely metallic, smell to it also. Modern synthetic watch oils do not break down in this way.

Much better...