
via makethebestofthings.blogspot.com
I've always used fish glue (from Lee Valley Tools) or 'mucilage' - the paper glue we used in kindergarten with the little slitted pink rubber top - to create crackled and crazed paint effects.
The minor aesthetic problem with mucilage and fish glue (which, just FYI, smells like dead fish) is that they both give a very glossy effect to the cracks, which looks sort of cheesy on some projects.
Using white glue or carpenter's glue offers a much softer matte finish, as detailed on this lovely blog, Make the Best of Things. I love this girl's work and I never thought of doing a crackle finish on cloth. How cool. She gives lots of detail about her experiments in creating crackle finishes with different base coats and degrees of thinning (both glue and top coat). Give 'er a click, eh.