People don't often look back on the early 1900's for advice, but what if we could actually learn something from the Lost Generation?
The New York Public Library has digitized 100 "how to do it" cards found in cigarette boxes over 100 years ago, and the tips they give are so practical that millennials reading this might want to take notes.
How to Clean Oil Painting?
Painting should first be well dusted and then rubbed gently with flat surface of a cut raw potato, the lather being wiped away with a soft rag.
Dirty part of potato must constantly be pared off in order to keep clean the surface applied to picture.
Finish off with a rub of pine linseed oil.
Wish I can help you.