Oil Pastels, Crayons, and Casein

August 2, 2008

I’ve been experimenting recently with combining casein medium with both oil pastels or wax crayons, and the results have been very interesting. For those unfamilar with these mediums, casein is a paint binder and glue made from milk protein. Oil pastels are made from a petroleum based combination of waxes and oil, and crayons use petroleum waxes. The specific ingredients often varies by manufacturer. Casein and wax are both emulsifiers with oil, so they all can work together to some degree, and within certain limitations.

Artists familiar with using oil pastels or crayons (as well as wax pencils) know that they have issues related to mixing them. Overpainting a lighter color of pastels on top of a darker shade will just cause them to smear into each other, and crayons will hardly function at all in that manner. However, I have discovered that when painting a clear casein medium over either pastels or crayons it creates a barrier preventing the colors from mixing together.

Attached below are two small samples I made combining these mediums. The surface is Arches watercolor paper, hot-pressed, 300# weight. On the left side of each image is a representation of different colors on top of black. On the right is each color separated by a thin layer of casein. In the Oil pastel image you can see on the right that the red and green have practically no effect on the black. The blue color can be seen, but smears drastically. The crayons look the same. However, when they are separated by casein, each color shows clearly to some degree, and doesn’t smear. Bear in mind the pigments in these colors are fairly transparent, so they don’t show up very intensely, but do have some effect. The texture this combination creates is very appealing, and would be rather difficult to achieve in any other fashion.

Oil Pastel sample

Oil Pastel sample

Crayon sample

Crayon sample

I apply the casein directly on top of the pastel or crayon, and let it dry. I can speed up the drying by using a hair dryer, and in a couple minutes can lay down a new color without disturbing the layer beneath. I’m uncertain how many layers is “safe,” since the general advice for these mediums is not to get them too thick. However, in this application they are a series of thin layers, not one thick layer, so it should be stronger in that sense. The most I’ve ever used is three or four layers.

Casein also makes a hard surface when it dries, and can help protect work from damage. It’s not a true varnish, however, since it is at best only water resistent after it cures. I would still recommend framing the finished work under glass.

Oil and wax also comes made into sticks or bars. They would also work with casein, but they are made of linseed oil, which would be damaging to raw paper stock. If the paper is sized first (shellac, PVA, or hide glue) that would be fine. Oil pastels and bars can also be diluted with solvents such as mineral spirits or turpentine into a thin wash, which can be used as an undertone for casein painting.

Now, there are some cautions I should mention. As I said, this is experimental, so use at your own discretion. Many oil pastels and crayons on the market are not made with the best of materials, even those sold for artists use. For oil pastels, I would suggest Sennelier, Holbein, or Caran d’Ache brands. Sakura/Cray-pas also make an “Expressionist” line of pastels they claim to be of high quality. Good quality wax crayons are rather difficult to come by and many are water-soluble. The kraft marketed type, such as “Crayola” crayons, would work in this fashion, but I doubt their permanence.

It’s also possible to make your own materials. Oil pastels and bars come in “blending sticks” which are sticks without pigment. These can be melted down under low heat and mixed with your own choice of pigments. The individual ingredients of wax and oil would take some experimenting to assemble into a workable stick, but it’s possible. Mineral oil, coconut, and soy (oil and wax) are options for pastels. For crayons, I’ve been experimenting with wax blocks sold for encaustic painting that are both clear and pigmented. I have articles on my website about how to make your own casein medium. Richeson/Shiva also sell a “casein emulsion” that you might try.



  1. That’s interesting; I wouldn’t have thought to use unpigmented casein as an isolating or protective layer-kind of like retouch varnish in oils.

  2. Yes, exactly. I want to do more tests on the adhesion and how well it holds up, but so far I’m very encouraged.

  3. […] of this I wanted to test the combination of casein medium and wax crayon or oil pastel layering I spoke of a few days ago. The crayons were drawn on top of watercolor paper. In one area I drew different colors of crayon […]

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