My wife bought some tempera paint for our grand daughter to play with when she comes over. I was curious how it would spray in an airbrush, so I thinned a little with some water and dumped it in my trusty Badger Patriot.. It sprayed pretty well when I got it thin enough, but coverage was very light. It might work OK for weathering. Then I got the brilliant idea of trying alcohol as a thinner. As soon as I started stirring, little lumps of pigment started forming. So I figured, no big deal I'll just rinse it out with water. Nope. Little lumps stuck all over the inside of the brush. So OK, I'll wash it out with some Windex. Nope. OK, I'll use some lacquer thinner. Nope. Then I'll use some Acetone. Still Nope. In the end, I had to swab all those little bits out. They stayed soft, but they wouldn't dissolve. The moral of the story: Don't experiment with thinners in your airbrush. I may mess with the tempera some more, but I won't use alcohol.
Don