When making a large frame to stretch canvas over, do you need to include supporting bars?

Wednesday, July 28th, 2010 at 12:58 pm

I am planning to make some large frames to stretch canvas over. Probably about 5 ft. x 5 ft. to 6 ft. x 8 ft. Do you need to put supporting bars across the frame… like in the middle… for extra support?… or is that not necessary? I noticed with the large canvases I buy from the store, they have bars all across the back to make it stronger.