Vridar

I'm also new to sewing machines, but not new to tinkering. Watches, cameras, guns, cars are a few of my previous interests. However, I do have many hours of college chemistry and am a fan of Bob Flexner's Understanding Wood Finishing. I have deduced Japaning of Singers is done with shellac. Shellac was and is used on antique furniture. It is the main force in French Polishing. From previous posts I have concluded shellac is used as the "clear coat" of vintage machines. Alcohol, any form, is used to dissolve shellac and will do so effectively. This means if Singers are Japaned with shellac and alcohol is used to clean them, the alcohol will dissolve the "clear coat." If the finish is thick enough decals probably would be undamaged, but once the shellac is dissolved and the decals exposed to the alcohol, they will be silvered, no two ways about it. Alcohol will not touch any of my vintage Singers for this reason.

My process is to use the least volatile solvent for the job. The sequence would be water (on non-exposed metals)/oil/kerosene/mineral spirits/alcohol/acetone/naphtha. To date I've not had to use more volatile than the in my tinkering with sewing machines.

Caveat: I'm using volatility as a measurement of ability to dissolve other hydrocarbons. This is not exactly accurate but a good indicator.