Depends on the type of canvas and ink used in the signature; acid-free, etc. Canvas in general will last much-much longer than any poster or print. It is a very secure way to preserve and protect any medium; paint or ink. It should not be necessary to put it under glass if it is not in direct UV light. I think you'll find some answers by searching "canvas vs. poster" or "canvas preservation"

http://zazagallery.com/blog/posters-...nvas-is-better. Hope that helps. Enjoy your new acquisition.