Friday, April 30, 2010

Green Earth

Green earth or terre verte is another historic earth pigment. It has been in continuous use for thousands of years, particularly for Medieval wall paintings.

Green earth is an iron oxide pigment. It derives its green color from the addition of complex silicates, such as celadonite and glauconite. The exact color of green varies based on the different proportion of these minerals. The best varieties are mined from Italy. I could have bought the imported color, but I wanted to find a local source. What I never expected, was that my source of this color would end up being fertilizer!

My mother, an avid gardener, suggested I look at a bag of fertilizer she had just purchased. The bag was full of Greensand, a natural product made for organic gardening.

At first I was a little skeptical, so I put the idea aside. I made a mental note to revisit it at some point. A little research and a consultation with a geologist friend gave me the answer I was looking for. Greensand is mostly glauconite, a version of green earth. I went ahead and prepared a sample.

I prepared the green earth exactly the same way as the other earth pigments. I washed the sandy powder. Then I levigated it, collecting only the silt, and set it out on a plate to dry.

The finished pigment. This variety is more of an olive, pistachio variety of green, at least without oil.

I recently bought a new palette. I put on several coats of linseed oil and let it dry.

These are all of the colors I've made so far.

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