D B Clemons - Casein History

What Is Casein?
Casein is a protein found in milk. The name comes from the Latin word for cheese, "caseus," sometimes called "quark." Raw milk is made of mostly water, some fat, proteins and other solids. When an acid, such as vinegar, is added to milk it will separate into solids (curds) and liquids (whey.) Two cups of milk will yield about 1/4 cup of casein. Precipitating casein is the first step in making cheese; although, what is typically used for that is an enzyme called rennet.

When an alkali is then combined with the casein it creates a strong adhesive. The alkali commonly used is hydrated lime or ammonium carbonate; however, those can cause the pH level to rise too high for artwork surfaces and some pigments. Borax is weak enough to not cause problems, and still make a very good casein binder.

If the idea of a paint binder made from milk seems odd, consider where oil mediums come from, or using tree resins as varnishes, egg tempera, or glues from fish or animal hides. Most mediums and glues are organic in nature.

When used as a paint binder it is water soluble, and can be thinned to a wash much like watercolor, or applied in a thick paint layer approaching that of oils or acrylics; although it shouldn't be applied too thickly. Even though it dries very quickly, it takes several months for the binder to completely cure, afterwards the paint is extremely water-resistant. It is about the most versatile medium there is, since it can be made into a size, a primer, and even combined with oil or acrylic paints. The true value of this medium for me was finding out how easily I could use it to make my own paints.

History:
Casein paint has been used for centuries and has been found on ancient Chinese and Egyptian artifacts. Early European settlers brought it to America as "milk paint." In the 18th century it was used to paint sets for theatre and opera productions, and that practice continues today. Its dull sheen surface makes it ideal for use under bright lights. It also photographs well, and became a favorite of many 20th century illustrators for that reason.

Once the casein has been extracted from milk it can be used in a number of applications, not all of which is food related. Jewelry and other small plastic items were made from casein under the brand name of Galalith, or "milk stone." It was even made as a synthetic fiber for fabrics called lanital.

There are records from the French writer Prosper Mérimée who recommended using casein as a primer for oils during the late 19th century. There were several commercial brands of casein house paint introduced in the early 20th century, such as Texolite, Kem-Tone and Luminall. As the world is becoming "greener," casein is being revisited as a more eco-friendly paint product. In 1933, Ramon Shiva created a casein paint for artists that is now sold by the Jack Richeson company.

Where Can You Get It?
Casein is a very easy paint to make on your own using supplies that are not difficult to come by. Other articles on this website will discuss the paint making procedures and supplies, but there are some commercial brands that artists can buy as well.

Shiva is perhaps the best known commercial brand of casein paint for artists. The main feature is their paint has an unlimited shelf life. I'm not certain about what they do to the paint to make it that way (preservatives must be added,) but I have tubes that are a couple decades old, and the paint still works well. They also sell a shellac based varnish and a medium from which you could make your own paints. I like their paint overall, but sometimes they can be rather watery and inconsistent. Their color chart is somewhat limited as well.

There's also a brand from Pelican called Plaka that I've not tried. I'm led to believe it is a low quality student grade product since Pelican markets it as a craft paint, and it isn't clear what it's made of or the pigments used, but it too has an unlimited shelf life.

There is a brand called Iddings Deep Colors, sold by Rosco, that is made for theatre set painters, and it comes in large cans, or 1 ounce sample jars. These sample jars are a good deal, @ $2 each compared to the $6 price of Shiva, but they will spoil after a few months, and they are only sold in a set of 23. There was one reference that claimed their paint uses soy, but I've not been able to verify it. Look for it at online stores that sell theatre supplies. A pint of their white mixed with gypsum makes a decent gesso. A couple of their red paints faded quickly, but the others held up well.

Handling:
If you've ever used gouache, you'll find casein handles much the same way, especially with its fast drying time. The "stroke" of the opaque paint is rather short due to the fast drying rate, but it can be watered down quite a bit and still holds very well, and fine details are easy to paint. It's wise not to overwork the paint with too many brushstrokes. It also dries to a matte finish. There are several differences compared to gouache, however. Mainly, gouache can always be re-activated with water, but casein is more water-resistant when dry and makes a tougher film. Like egg tempera, casein is a good choice for underpainting oils, but it's more absorbent, so an opaque layer should be sealed with a thin coat of bleached de-waxed shellac, or else mix the casein with oil paint or medium.

Painting Tips:
When painting over a dried layer, it's a good idea to use as little water as possible or else the bottom layer will lift. You can glaze this way or paint over a toned underpainting. If the paint is applied too thick it tends to cake up, which will crack over time, and underlayers can absorb some of the binder on top. It's better if top layers have more binder in them. Instead of painting over an area you don't like, I recommend just wiping it off to make corrections.

To blend a media such as casein that dries this quickly, it's best to mix your values on your palette first, and then blend them together on the surface. I like it when the brushstrokes show, so I prefer to do as little blending as possible. The overall surface size I use is not that large, about 18 inches to 2 feet maximum. To paint large opaque strokes you'd have to mix up quite a bit of paint, which can dry too quickly. The brushes I use are rather small, except for washes. You can re-wet the paint on your palette somewhat with water, but after a while it becomes unmanageable. I typically only squeeze out small dabs of a few colors for an isolated area, which is a method I've also adopted for oils and acrylics.

When painting wet paint over a dried opaque layer, even if it's the same mixture, the fresh paint will turn a shade darker. The solution in that case is to adjust the new paint to a lighter value to match the shift, or re-paint that whole area.

Soft brushes, especially taklon synthetics, work very well with casein. It helps to have a gentle touch if you're overpainting any areas. Even stiff brushes can be used for texturing. Use natural hair brushes sparingly if at all, since the amount of water required here can damage them over time.

Other Notes:
Another compatible emulsion is methylcellulose, which is made from wood pulp. The main advantage is it never spoils, although it can grow mold. It's also a good oil and water emulsion. A little bit goes a very long way. 1 tablespoon made 4 ounces of medium that's lasted over a year.

Melted beeswax paste (with turpentine or spirits) is compatible with casein paint, and creates interesting textures.

Always use distilled water when painting since the bacteria in tap water can accelerate the growth of mold in casein.

For casein making recipes that include ammonia you need to have a properly ventilated area. Shiva paints have a strong odor to them that I suspect is ammonia; although, there's no warning about that on the label. Their odor takes a while to dissipate as the paint dries and then the odor is gone. The substitute I use for casein binder is borax and it has no odor, but may irritate the eyes or skin.

Resources:
Shiva Paint
Iddings Deep Color
Pelican

Reference Books:
"The Painter's Handbook" by Mark Gottsegen
"Paint Making and Color Grinding" by Charles L. Uebele (free online)