Casein & Milk Paint

In Jan Dickey's practice, egg tempera never works alone — its constant partner is casein, the milk-protein binder also known as milk paint. Where the egg glazes, the casein covers. At the workshop the two were treated as a complementary pair, the way a painter might keep both a transparent and an opaque medium on the table.

What it is

Casein is a binder made from milk protein. You can demonstrate its origin like cheese-making: heat milk to near-boiling — never actually boiling (the same principle as rabbit skin glue: boiling denatures the protein), then add an acid — citric acid or vinegar. The milk immediately separates into curds. Those curds are the casein protein; dried and powdered, they become casein powder.

In practice, Jan doesn't make it from scratch — he buys casein powder commercially — but understanding the curdling shows you exactly what the material is and why heat has to be controlled.

How it behaves

Against egg tempera, casein is the opaque one:

• More opaque — it cannot glaze the way egg tempera does.
• More matte and dry in surface quality, slightly chalky, without the egg's faint waxiness.
• Faster drying.
• Like egg tempera, it is an animal-protein binder that re-activates with water — unlike acrylic or oil.

Working the pair together

This is the part that reframes both materials. Jan uses casein for opaque areas and egg tempera for translucent glazing layers, and together they do the work people usually reach for oil or acrylic to do. The mental model is simple:

• Egg tempera = transparent / glazing — a watercolor-like quality, light passing through.
• Casein = opaque coverage — solid, matte color that sits on top.

And because both reactivate with water, you can layer casein over egg tempera (Jan does this routinely), building a painting from translucent depths up to opaque accents — all in water-based, animal-protein media, with none of the solvents or plastics of the modern paint aisle.

Jay's Studio Note

What I took from the casein session was less a recipe than a system. I'd always thought of "natural paint" as a charming but limited substitute — fine for a flat wash, not for a real painting. Seeing egg and casein used as a transparent/opaque pair changed that. Between them they cover the whole range oil does: luminous glazes from the yolk, solid opaque passages from the milk, and you can stack one over the other because water is the shared language. It made me want to set up a deliberately dairy-and-egg palette in the studio just to see how far two animal proteins can go. There's also something I keep turning over — that the curdling that ruins your coffee is the exact reaction that gives you paint. Same chemistry, different intention.

References

• Jan Dickey, Tempera & Distemper Workshop, Material Memory Studio, Seoul, 7 June 2026. Jan Dickey is a New York-based painter, curator, and art writer. Jan Dickey at Material Memory Studio
• Kremer Pigmente — commercial casein powder supplier referenced in the workshop