A Paint-Making Experiment with Murdoch’s Mystery Rock

A thoughtful person by the last name of Murdoch, who happens also to know a bit of geology, enjoyed my display over at Kingston Square Arts, bought a print, and then came back and left me a box of rocks. And today I embarked on a paint-making experiment with one of those rocks.

It is so awesome to me that people bring me rocks, because that means when they see a colorful rock somewhere, they remember the work I’m doing with them and they want to help. I love it. Since I didn’t ask permission, I won’t use his full name in this post, but usually when someone gifts me a rock, I try to use part of their name in the name of the paint when I’m done.

There were two bags full of nice large rocks. The first bag contained a tricolor sandstone looking rock from just west of Huntsville, Arkansas. So still an Ozark pigment. The second bag are some other interesting rocks from Texas. My friend Michele and I gathered some rocks the last time I was in Texas visiting her, too. So I have enough now to make a Texas collection. Since my husband is from south Texas, it’s a fitting first ‘other’ place I’ll feature.

The tricolor mystery rock

The Murdoch rock and the three shades of color.
The Murdoch rock and the three shades of color.

What’s so mysterious?

When I grind up a large rock, I have enough pigment to do some experimenting with. So I mixed all the powder in water and let it settle. Immediately after mixing it up good, I poured all the colored water into other jars and saved the sand that settled quickly. That’s what is in the jars to the far right in the photo above.

The first mysterious thing was how little color was left in that sand! Usually it’s pretty much the same color as the water. That part is what I call the ‘heavies’, because it drops out first.

So I let the water settle a couple of hours and then poured off the still densely colored water into more jars. What had settled were the particles lighter in weight than the first sands and I kept that in a smaller jar and put it in the dehydrator to evaporate the water from it. This part is what I call the ‘middles’. These weren’t mysterious. They looked about like all the other middles do.

The ‘lights’, the parts that stay suspended longest, are the other mysterious thing about this rock. Usually they’ll settle overnight, or at most, in a day or two. These showed no signs at all of settling. It must be a very fine clay. If I can get them to settle, I’ll bet it makes a very smooth paint.

Making the suspended particles settle

One of my first jobs in the science field was in a water quality laboratory at a municipal water plant in Houma, Louisiana. One of the tests we did is called a ‘jar test’. The purpose is to see how much chemical is needed to cause the suspended solids in water to ‘flocculate’. When you floc the water, the suspended solids clump together and become heavier than the water.

Then the solids settle to the bottom and the clear water can be poured or siphoned off. Or as was the case in the water plant, the sludge is filtered out in giant sand filters. The sludge is then disposed of. In this case, the sludge is what I want to keep!

A Paint-Making Experiment & a little chemistry

Yesterday’s paint making experiment was with a using charred bone to make black paint. Today’s is on how to make the suspended particles of clay settle out of the water.

I decided to try alum (aluminum sulfate) to see if it would cause the clay particles to settle. The way this works (without going into balancing equations and all that kind of chemistry stuff, which I’d have to learn all over again to explain) is that the alum has loose protons, which are positive charges. The clay particles have loose electrons, which are negative charges.

When the alum dissolves into the water with the clay all floating around in it, the two opposite charges attract each other and make bigger particles than either of them alone. And so they’re heavy enough to sink.

To make it work a little faster, I added the alum to warm water before putting that into the colored wash water I got from the rock.

Paint Making Experiment
I used 1/2 tsp of grocery store alum in 1 cup of warm water, then added it to the 4 cups of clay-colored water. Within a few minutes, I could see the clear water level at the top, another layer of flux, and the bottom layer of still suspended particles.
It's working! The suspended clay is beginning to settle. Clear water is gathering at the top.
30 minutes later: It’s working! The suspended clay is beginning to settle. Clear water is gathering at the top.

The waiting part of a paint-making experiment

So now I’m still waiting. Once all the settling stops, if it’s not complete, I’ll add another cup of warm alum water and let it start again. As it settles and the band of clear water forms at the top, I siphon that off and throw it out. Eventually I should have a good layer of clay at the bottom to work with.

Then I’ll put it into small jars and dehydrate the rest of the water out. Finally, I’ll get to see if it makes a good paint. I’ll let you know how my paint-making experiment turns out with an update here!

Madison Woods is an author, artist, and Paleo Paint maker living
with her husband in northwest Arkansas far off the beaten path. She uses paint made from rocks, and mostly Ozark pigments to create her paintings.

Contact Info:
Email: Madison@wildozark.com
Instagram: @wildozark
Facebook: @wildozark

Use the buttons below if you’d like to see the kinds of things I’ve painted with my Paleo Paints. Raptors are my favorite subject to paint, so I’ve started a project to do a portrait or three of each of the species known to visit or make homes in the Ozarks.

Bone Black

Bone Black Swatch from Wild Ozark Paleo Paints.

I made bone black, from a cow vertebra that I charred inside a small tin inside the wood stove. Previously I’d used charred wood from hickory and oak. It has been a difficult paint to re-wet and it never reached the depth of black I wanted. It was also grainier than I liked. The charred bone worked great!

A historical color, the blackest of blacks

Bone black has been a thing since the very early history of mankind. Charcoal from wood has always been more convenient and served well enough for most needs. But like me, someone somewhere must have need a deeper black than they could get from charred wood. Here’s a link to a little more info about that from Pigments Through the Ages website.http://www.webexhibits.org/pigments/indiv/recipe/boneblack.html

I’m not sure what that last line in the 19th century recipe means, but I may need to rinse the pigment before making the paint. We’ll see what happens. I didn’t find that link until writing this post, and I had already made the paint before that. Maybe for the next batch I’ll try it.

The process for making bone black

First I broke the bone into small enough pieces to fit inside the tin. The ashes from yesterday’s fire still occupied the stove. Too much air causes the bone to burn rather than char. Burying it under ashes inside the tin helps with that. Then I built the fire over it and let it burn down.

Charred bone for bone black handmade watercolor Paleo Paint. Fresh out of the wood stove. The bones were cleaned and thoroughly dry before charring.
Fresh out of the wood stove. The bones were cleaned and thoroughly dry before charring.

The charred bones were a lot lighter and easier to break down in the mortar than they were before. The bones were really difficult to break into small enough pieces to fit inside the tin. But afterward, the crushing was a breeze.

It’s still a very messy color to make. The powder floats into the air just as much as the charred wood does, so wear a dust mask if you make this. Or have a fan blowing the dust away from you. Just don’t put the fan too close, or you’ll blow your pigment out of the screen.

Once I had it crushed as fine as I could do with the mortar and pestle, I sifted the powder through a 200-mesh screen.

I sifted all I could through the screen, and put the difficult bits back into the mortar. Then and repeated the sifting process. After that was done, I put the more difficult bits into a small jar and added enough of the watercolor media to cover it plus some. I’ll strain that later and use the fluid to either make a sheer black or add it to the next fine sifted powder on the mulling board to see if it intensifies the black any.

The paint

Bone black on the mulling board. Such a nice smooth black!
Bone black on the mulling board. Such a nice smooth black!
Making black is always messy business. This one is worth it, though.

Once it dried, it doesn’t ‘smear’ when I rub on it – which is a good thing! It is a flat black, not glossy, but it’s exactly what I need to finish up my red-shouldered hawk painting.

Madison Woods is an author, artist, and Paleo Paint maker living
with her husband in northwest Arkansas far off the beaten path. She uses paint made from rocks, and mostly Ozark pigments to create her paintings.

Contact Info:
Email: Madison@wildozark.com
Instagram: @wildozark
Facebook: @wildozark

Red leaves of black gum (Nyssa sylvatica)

Deep red leaves of the black gum at the end of summer.

Black gum leaves begin turning deep red near the end of summer, sometimes long before any other leaves are starting to think of autumn.

This color is made from the late summer red leaves of black gum (also called black tupelo). It’s a tree native to the Ozarks and one of the few light-fast sources of plant pigments that I’ve found.

Red leaves of black gum, poured into pans and paint swatch painted.

Late Summer Shades

I can actually get three different shades of color from red black gum leaves, depending on when the leaves are gathered and/or how they are treated. The green lake pigment is a very nice shade of green, but it isn’t light fast.

From left to right: green lake pigment, water and ethanol extract, water only extract.
From left to right: green lake pigment, water and ethanol extract, water only extract.

The two brown shades are both light fast, based on my test strips that I hang outside in full sunlight. I leave them out for at least 4 weeks and they get full afternoon direct sunlight.

The green shade was made by precipitating pigments from the water and alcohol extract with alum and calcium carbonate. I love the color, but it doesn’t hold up to the light-fast test. So far it’s doing fine indoors, though.

The center shade was made using a water and alcohol extract, and the right shade was made using only water to extract the color from the leaves.

Red Leaves of Black Gum

The center shade will be included in my Soul of the Ozarks Collection No. 3, the next set of colors to be released which will include 9 colors from earth and plant pigments.

Wild Ozark Paleo Paints, Soul of the Ozarks Collection No. 3
Wild Ozark Paleo Paints, Soul of the Ozarks Collection No. 3

It’ll be to be released on November 23, 2018 at the Holiday Market to be held at the Walton-McBride Studio in Fayetteville, Arkansas. This set will be exclusive to that market until after Dec. 16 and after that I’ll list any sets left at my Etsy shop.

The hours and location for the Holiday Gift Market
Click the image to go to the website: https://communitycreativecenter.org/calling-all-artists-holiday-gift-market/

Making the Colors

gather the red leaves

Depending on when you gather the leaves, it may give you a slightly different shade of color.

Add to a pot of water

If you just use water, a lot of the red will remain in the leaves and not go into the water and will yield a color closer to the right hand image in the photo above.


I boiled the leaves gently. It may yield another shade to extract with alcohol and not boil it at all. I haven’t tried that yet, but it’s on my list of things to do.

The extract of red leaves of black gum trees.
The extract of red leaves of black gum trees.

Strain the water out. I use cheese cloth folded over several times.

I use cheesecloth to filter.
I use cheesecloth to filter.

Add solution of gum arabic. This makes a watery paint that will need to be panned several times as each layer dries. Store your paint in the refrigerator or it will mold and/or ferment. That, too, might yield a different color and is another experiment for the future. I’d leave the leaves in for that one.

Plant Pigments – Experimenting and Searching for Green

Generally I don’t use the plant pigments because they’re fugitive, meaning they fade over time. Sometimes they completely disappear.

However, I’ve found two sources that actually intensify with exposure to light (full sunshine) and so I am experimenting with extracting the pigments from them.

The Sources of my Plant Pigments

Sassafras makes a nice yellow and orange, whereas Black Gum makes tan and green.

The differences in the colors produced from one plant are due to a few different things.

First, the time of year matters. If I gather leaves early in the season, sassafras gives me yellow. If I gather the autumn leaves, I get the orange. These two colors are sheer in nature but can become quite bright with UV exposure.

If I make lake pigments by adding an alum solution and following with calcium carbonate to flocculate and collect the precipitating pigment, I get yellow from the autumn leaves of sassafras and a very nice green from the black gum.

Maybe other shades will result from using other solutions in this lake process. I’m only beginning the experimentation. Then I’ll also test the finished paints from this way of getting the colors to make sure that they, also, are light fast and UV safe to use in a painting I don’t want to fade.

Many organic and even metallic inorganic will also oxidize and turn brown. This has been a big problem with any plant pigments I’ve used too, except the sassafras. I’m still testing the green from the black gum to see if it’ll turn brown.

How to Test the Color Stability

I test by leaving half of my test strip outside so that it gets full sunlight exposure and open air for 4 weeks. At the end of the 4 weeks I compare the other half of the strip that has remained inside in the dark to the one that hung outside.

A little bit of change is tolerable, but too much indicates that the painting won’t look the same after a decade or two. Watercolors are fragile colors to begin with and I always frame mine, and recommend buyers to frame theirs, under conservation glass to protect it from UV light, even indoors.

Precipitated Plant Pigments

Here’s what the filter cakes from my lake experiment looks like. I’ll write up a full post about what I did and how it looked throughout the process later.

Plant pigments obtained from precipitating with alum and calcium carbonate.
The yellow lump is from the autumn leaves of sassafras and the green one is from the autumn red leaves of black gum.

Where to find my Paints

I sell my collections at Etsy and through my online shop at Wild Ozark, the main website. Eventually I’ll have raw pigments to sell, too, for those who want to make their own paints of any sort from Wild Ozark colors!