I did this little painting a couple days ago on location in Rhinecliff, New York. The setting sun turned the Hudson River into a path of golden light.
The painting is 4 x 7 inches on watercolor paper, painted almost entirely with a half inch flat brush.
The medium is casein. This is my first outing with casein, and I'm already madly in love with it. It is a water-based paint medium with working properties that resemble gouache, cel vinyl, and, in some respects, oil. I've used all of those latter paints quite a bit, but casein has qualities all its own. It can be used transparently, but it has great opacity when you need it, something often lacking in acrylic.
It lends itself to bold handling and 'finding the image in the paint.' At left is the first stage of the painting above, where I stated the simplest dark/light relationship before going in with the brush to find the details.
Casein is one of the oldest paints, older than oil, but it had its heyday starting in the 1930s, when they figured out how to tube the stuff. It was a favorite through the '40s and 50's, before acrylic came in. Two masters of casein were the illustrators John Berkey and Harry Anderson.
To my knowledge, these days, the only major manufacturer of casein is Jack Richeson, who bought the Shiva name, and keeps it going as a niche business. Here are the colors I have in my paintbox:
Cad red scarlet
Cad yellow light
Cad yellow med
For the painting of the house by the river, I used only white, cobalt blue, golden ochre, venetian red, and a little raw umber. If you want to try casein, I'd recommend getting just a few colors at first and taking them for a spin.
You can get a good starter set on Amazon: Jack Richeson 37-Ml Artist Casein Colors, Set of 6
Note: in my book