Desert Varnish

What Is It?

Desert Varnish is a dark coating on rocks originally thought to be found only on stone in arid regions. Actually it occurs worldwide and in many environments, varnishes may even exist on Mars as suggested by observations on both the Viking and Mars Pathfinder landing sites. Desert Varnish occurs in many different colors and densities, from a glossy black, all shades of brown and some with orange tints. How is the varnish made? What is it comprised of? How do I use this knowledge in my wall art and stone carving?

Desert VarnishInitially it was thought that the varnish was created by substances being drawn out of the rock, a weathering of the stone or a chemical reaction changing actual surface of the stone. Further investigation shows however that the varnish has high concentrations of clay which could only come from the outside of the stone. The clay then catches additional substances that have a chemical reaction under the heat of the sun along with a little moisture from the air mixed in to make the all different colors of varnish that is found. In the end the varnish is indeed becomes a light coating, typically less than half a millimeter thick, of minerals, clay and bacteria deposited on the rock surface.

Desert VarnishAs we know Desert Varnish is comprised of three major elements. The first is clay that adheres itself to the surface of the stone. Next let us look at the minerals which are the second part of the recipe. The region where the varnish is created greatly affects the color layered on the stone. If the region has a high concentration of manganese oxide in its mineral composition the varnish created in that area will generally be a dark color more on the glossy black side. A region that has a high concentration of iron oxide will produce browns and varnishes with an orange tint. These minerals blow around in the air with the dust and attach themselves to the clay. Add a touch of moisture, like morning dew, and combine with the heat from the sun to create the finally ingredient, bacteria. These ingredients and anywhere from 50 to over 100 years and you will start to see the beginnings of a coating of Desert Varnish.

I had to take all this information into account when figuring out to recreate Desert Varnish in my studio to help perfect the creation of my wall art. When I first started stone carving I collected all the stone myself. The stone was naturally aged and many pieces did have some patina or Desert Varnish on them. When I started purchasing the stone for my carvings direct from the quarry there was no aging and therefore no contrast when I went to carve on them. I studied the aspects of Desert Varnish in nature and recreated the recipe and also they way in which to hurry the whole process up. The final results are wonderful pieces of wall art that have the look and feel of Desert Varnish but did not take the 50 to 100 years to create.

Ron White, stone carver and entrepreneur, has been carving stone since 1993, and is shown in more than 40 galleries across the US. Prior to beginning his work with stone carving Ron has worked extensively with leather, wood cabinetry and even jewelry. Learn more about Ron White and his work at at

This article was published on Friday 19 November, 2010.
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