I love my thermofax machine. (For a very short description of what that is and what one does with it see this site by Karen Stiehl Osborn). This is just about the best thing that's happened to screen printing in years. It's so much easier than preparing and burning photo silkscreens.
As noted on Karen's page, I've always been told that the screen material needs to go through the machine with a photocopy because it's the carbon on the surface that causes the plastic screen backing material to burn away. That's all well and good if you've got a photocopier or laser printer in your studio, which I do not. On a lark I tried running a test piece of paper painted with black tempera paint (Pearl Paint) through the thermofax. And, what do you know, it worked great. Charcoal works too. The charcoal seems obvious--it's carbon. The tempera paint was a surprise. I don't know if there is carbon in the black paint, if something else is making it work, or if other colors would work. I'm just happy it works!
I made the screen below by making a quick gesture drawing with tempera paint in a dental syringe. The printed fabric is built on top of the result. The fabric is a bit too cute for most of my purposes, but it was fun to paint. I think it might turn into the lining for a scarf.