My 200 year old home has ceilings made of stretched canvas in what would have been the front parlor and the current living and dining rooms. They look just like a ceiling with a very smooth surface. You can't tell they are made of canvas unless you carefully poke it and the ceiling lifts as you would expect it would if made of fabric.
The parlor and dining room ceilings are in excellent condition. The living room ceiling could use a new coat of paint but I've read that it could cause the ceiling to sag.
Anyone out there who's dealt with a canvas ceiling and knows what to do?