I have an old painting about 40 in X 40 in by Jon Sebastian who is he?

Question

The painting is probably painted in the 20's or 30's

Answer 1

This is a visual question. You have failed to provide visual clues. Give us the picture. You are saying that the picture is done during a twenty year period. On what evidence? The size is immaterial. What is the subject. Is the guy good enough to warrant any passing notice in the art world? How can we answer your question justly, please give us something to go on. use the extra info feature.