Why paint on canvass because: 1. It expands and contracts with the paint. What problem does that prevent? Answer: It prevents cracking. 2. A large canvass can be unstretched, rolled up, and easily shipped. When we roll a canvass, what side should the paint be on? The canvass should be rolled with the paint on the outside to prevent cracking. 3. Canvass makes paintings easer to restore because the paint can be removed from the canvass, recanvassed, repaired from the back, and restretched.