I've started a flickr set dedicated to various crackle paint textures.
The one pictured is Golden brand Gel Mediums Crackle Paste over Golden brand Black Gesso over an Ampersand Hardbord.
I used the side with the faintly printed logo thinking you'd never see it. Somehow the ink from the logo leeched up through the gesso and crackle paste to the point where it was clearly legible. I guess I should have also sealed the Hardboard with a primer, as the manufacturer advises. (Or just use the pristine side, although I had planned to be frugal and use both sides of every $5 board I bought.)
I had to use the Photoshop Black and White filter to pull yellow out. Even though the logo seepage pattern looked black, pulling yellow out made the logo invisible. It also made the image black and white, but that could be considered more of a feature than a bug.
If it looks a little gray, it's because I didn't clip anything to white. You can always make parts of it white later. You can't really undo that once you've done it.
UPDATE
I documented the retouching process. It ended up being fairly interesting. I used the Black and White adjustment layer, and LAB color


Excellent, I'll be using that. Have you ever checked out http://www.cgtextures.com/?
Thanks. I'm scanning some more today for the flickr set.
:)
cgtextures.com is great. I used to post in the forum there from time to time, but he seems to have discontinued the forum.