Making Paint out of Rocks

Yes, you can make paint out of rocks. I’ll admit it takes a bit of effort, but there is something so exciting about picking up a rock, and discovering if it will make a good color-or not. The first magical thing about this is that a rock can look like one color when it’s solid, and another color when it’s pulverized into a powder to make pigment. Pigment is what gives paint its color. If you use oil for example, the oil is the same color no matter what color of paint you make; the oil is the binding material, and the pigment is what gives it the color. So getting back to the magic part-a pink rock gave me orange paint, a grey rock gave me green paint, and yes, a yellow ochre colored rock gave me yellow ochre color. But then one super bright orange rock gave me literally no color. I can’t explain it, I need to talk to a geologist. 

At one time, these rocks were on the roof of College Center on the NCC Bethlehem campus. I have no idea why there were rocks on the roof, but there were, and when it was decided to take them off. Walter Heath, ceramics professor at the college when he learned that they were being removed, asked where they were going. When he was told they were going to throw them away, he convinced them instead to dump them at the East 40. 

While I was in the process of proposing the residency, I picked up a handful of the river rocks. I began the hard way, smashing them with a hammer. (Don’t do this at home unless you are wearing safety goggles, and have the rocks in something so shards don’t go flying all over the place.) Once I pounded the rock into little chips, I used a granite mortar and pestle to grind them into powder. I used some egg yolk and this powder to make egg tempera paint. I also tested some that I ground down into finer particles with a glass muller. I got two slightly different colors from each rock, the more gritty rock would usually be darker, the more finely ground lighter and somewhat different in color. You can see my egg tempera swatches and a photo of the rocks they came from above.

Particle size is not the only thing that affects the color; rocks heated to different temperatures will change color. I did a test tile with 9 different pigments, 8 of them pigments I made and only one bought pigment. While the clay was wet, I cut the tile in 3 sections so each section can be fired to a different temperature. I’ll have to share the results of that when they have been fired. 

Walter had already done some rock grinding pre-Covid, with the intent of using them in making glazes. He is letting me use a tool that I didn’t know existed, something he calls a “knuckle grinder.” Apparently it’s a prospector’s tool. Contrary to the title, this contraption is less dangerous than my hammer method since the rocks are way more contained. It’s a simple and ingenious invention, see the first photo at the top. There is a solid metal cylinder with a handle; and another metal cylinder that has a bottom and sides but no top, just large enough that the heavy cylinder can slide down into it. You put a rock in the hollow cylinder, grab the handle on the solid heavy one, and smash the rock below. There is a mechanical rock grinder and ball mill that I will hopefully use later in the residency, but bringing in the machines is for when I have a larger quantity to grind. I’m still really only in the testing phase, figuring out what is worth grinding. It’s a very slow and laborious way to get colors, I wouldn't blame you if you said I've got rocks in my head.. And yes, I really will eventually do actual paintings with these paints.