Even though I look at 1000’s of paintings a year evaluating them for art conservation needs I’m still often surprised at how dirty a painting is. Its unexpected because the image and colors look so even. If something were “dirty” you’d think that you would see, well, crud and dirt. But you really can’t see HOW discolored, dirty, grimy a painting is until you get a test done.
This really great quality western art painting came in the lab after it was ripped/damaged in shipping. The client was stupefied to see the cleaning difference… and ecstatic! The cleaned painting was a vision, full of fabulous colors!