How to Make Watercolor Paint From Rocks
Pigments for Watercolor Paints Surround You
Look around at the ground around you. What is the predominant color? That's the base color for a palette of colors representing your own environment. If you start looking closer, you'll find lots of different shades of earth colors. And almost all of them can be made into watercolor paints!
Around here it's yellowish-browns and a lot of reddish-browns.
Where I live there are a lot of sandstone rocks. All of the soil here is made from ancient sandstone, eroded over time. But over on the next mountain, the predominant stone is limestone and the colors are more shades of gray.
Pigments for watercolor paints can be derived from rocks, soil, clay, and plants. The ones from plants are generally not going to be permanent (they're 'fugitive'), but there are a few that are.
Almost all of the rocks, clay, and soils around you will yield a palette spanning shades of browns, grays, or reds. Some are more yellow, some more red, and some can even be shades of blue or green, depending on where you live.
Most often it is iron oxide that gives a rock (and ochre) its color. Iron oxides come in many shades of color.
Tools and Supplies You'll Need
You can make a very basic paint without getting complicated. If you find this process as fascinating as I do, you'll probably become interested in refining your technique. Some of the ways to make high-quality paints are more complicated than what I'm outlining here.
This article is going to show you how to make a basic paint. Before you get started, first you'll need to make your gum Arabic solution. You can buy this solution already prepared from most art supply stores or Amazon.
Some Tools You'll Need:
- dust mask
- safety goggles
- stainless steel mortar and pestle
- gum Arabic
- essential oil of cloves
- strainer (the kind in the kitchen department to filter grease)
- small containers to hold the paint
- palette knife
- tempered glass cutting board
- small (2-4 oz) canning jar
- canning funnel
It's important that you don't breathe the rock dust. That's why a dust mask is on the list of supplies. Better yet would be a respirator. Safety goggles will protect your eyes from flying shards of rock.
Collect a Rock
Some rocks are going to be easier to smash than others. Sandstone is a lot easier than most. Granite is on the very hard end of the scale. If you are fortunate to live in an area where colorful minerals exist like malachite or azurite, you're in for a real treat.
If you are familiar with minerals and know the identity of your rock, you can find out how hard it is by looking at the Mohs Hardness Scale to determine how hard it will be to reduce your rock to a powder. Rocks on the soft end will be the easiest, of course!
Break the Rock
The rock I'm using for the purpose of this demonstration is a yellowish shale. It's abundant in one area of our property and makes a nice color.
Whatever rock you choose, start with a small chunk or a few small chunks. If it's too large to start out, throw it against another rock to break it into smaller pieces.
Grind to a Powder
The object is to grind your rock to as fine a powder as you can with the tools you have. If the rock is hard, I'll use the hammer to the back of my pestle to break it smaller. Eventually, it is small enough to grind with the pestle in the mortar.
Put your strainer in a canning funnel on a jar. Pour the contents of your mortar into the strainer and sift the fine powder through, letting it fall into the jar.
Dump the larger pieces back into your mortar. Keep doing this until you have all of the rock that will grind done. Some pieces just might not reduce. Throw those pieces out.
Keep a Color Journal
I try to remember to take pictures of my rock before I grind it. After you have the powder, rub a little bit of it onto a sheet of paper. This will give you an idea of what color paint you'll get.
Mix With Gum Arabic Solution
Once you have the powdered rock, you have a paint pigment. If you wanted to make oil paints, you'd add it to linseed oil. If you wanted to make tempera paints, you'd add it to egg yolks.
But I make watercolors, so I add it to the binder for watercolors, which is gum Arabic.
This is where the tempered glass plate (if you're using a cutting board, make sure the smooth side is up) and palette knife comes in.
Put the powder in a heap in the center of the plate. Make an indentation in the center of the pile. Add some of your gum Arabic solution to the little indentation.
It's impossible for me to tell you how much exactly of the solution you'll need because I don't know how much powder you produced. I never work with more than a tablespoon or two of powder at a time.
Use the palette knife to mix the powder together until it makes a wet paste.
If you intend to continue making paints, you'll want to invest in a muller. A muller is a glass pestle with a flat bottom that is used on the glass plate to mix the paint. They are fairly expensive, but they enable you to make a much better quality paint.
Record the Color
Next, to the rub you made, make a test swatch of paint. Here's the entry in my color journal, with a piece of the rock, a rub, and the paint color.
Your Finished Paint
Once you have it mixed into a paste, put the paint into something so you can use it once it dries.
Artists of old used seashells as little cups. You can buy standard pans and half-pans made from plastic. Or you can use acorn cups, old bottle caps (from glass bottles or from the liter drink pop bottles). Anything at all will work, but some are more easily organized than others if you start making a collection of paints.
Here's a photo of one of my paint collections. I used a wooden block to hold the paint and keep it in a tin with a hinged lid.
Collect Rocks With an Eye for Color
If you're like me, you probably collect rocks because you like them. Now when you collect a rock, you'll pay closer attention to other properties that are important.
- How hard is it to break?
- What's color is it?
- Will it make a good paint?