Oil paint is not my friend.
To be fair, powerful solvents in general are not my friends. I get headaches at the drop of a hat, so working with paint thinner does not rank highly on my list of enjoyable activities.
That’s why I’ve always painted with acrylic. I’ve also taken steps to minimize how much of that acrylic escapes my studio — from using multiple jars of rinsing water, to multiple trays for evaporating that rinsing water, to stripping off the dried acrylic residue and trying to repurpose it.
Still, I don’t want to work with a medium that’s basic liquid plastic if I don’t have to. That’s where milk paint comes in. Rather than using acrylic as a binding agent, it uses a protein found in milk.
There are some key differences between acrylic and casein paint, though:
- Casein is inflexible, while acrylic maintains flexibility when it dries. This means that acrylic is good for painting on stretched canvas, while casein is only really suitable for rigid substrates like wood or canvas-covered MDF.
- Casein dries to a velvety, matte finish, while acrylic can be pretty shiny unless you add matte medium.
- Casein takes a long time to dry fully. This means that you can wet it and re-work it. Once acrylic dries, it’s dry.
- Casein works great as an underpainting medium, while acrylic has some drawbacks.
- Casein dries to the touch very quickly. Acrylic stays wetter for longer, and the addition of retardants can further extend this drying time.
- Casein has a bit of a smell, while acrylic doesn’t really smell like anything. I have to say that casein’s smell isn’t really objectionable, though. It smells kind of like lemon window cleaner, but the scent is very light.
These didn’t really influence my decision to start using casein paint, because I was more focused on reducing my dependency on acrylic media.
Here are two of my paintings. The first is acrylic, the other is casein:
As you can see, there are some differences in vibrancy and transparency. I also had to change a lot of my techniques in order to successfully work with casein. For example, I like to work wet-on-wet. That’s a bit more challenging with casein, because the under layers are pretty much dry to the touch by the time I’ve scooped up the next color I want to work in. I’m also not used to being able to re-wet and re-work paint once I’ve used it.
Casein also tends to have more opacity than acrylic. (This opacity can, of course, be reduced with the addition of a little water.) Some acrylic pigments are very opaque, but others are quite sheer — almost more like a glaze. Casein goes on like it means it.
I’ve noticed that I also have to work more quickly with casein. If I take too long, it’ll start to dry on me. The same dry-brushing techniques that I was taught with acrylic don’t really work here.
All in all, while working with casein has taken some adjustment on my part, I love it. I actually prefer it to acrylic now, especially when it comes to opacity. It’s a beautiful medium that’s been in use for millennia, and one that I hope sees even more use in the future.
Marble Crow 