The printing washes out completely. These are a lot of fun to work on, and there are several sizes and styles. But as I say, I would use poly batting so it doesn't shrink when you wash it.
Here's a link to a picture of the baby quilt done with applique. I think it's stunning--it would be a real heirloom (and a whole lot of work!)
http://www.benartex.com/projects/p_wholecloth_big.php