Is a painting a secondary source?

A painting is a secondary source. A painting may be done years after the event has happened.

For example, the painting of Betsy Ross showing the American flag she made to George Washington is in many textbooks. The painting was made by an artist commissioned by a member of Betsy Ross' family. There is no proof that Betsy Ross actually made this flag.

http://articles.baltimoresun.com/2002-01-13/news/0201130008_1_ross-sewed-betsy-ross-weisgerber