48 Watercolor artist | JUNE 2020
GOUACHE AND CASEIN
I sometimes use gouache in combina-
tion with casein. Like gouache, casein
is a water-based opaque paint that
dries matte. Th e milk-protein emul-
sion is stronger than the gum arabic
in gouache or watercolor, but not as
strong as acrylic. Th e emulsion in
casein keeps the paint from being
sticky or gummy as it’s drying.
Th erefore, casein fl ows more readily
than acrylic off the brush. Casein dries
toa moreclosedsurfacethangouache,
meaningthedrypaintdoesn’treacti-
vatewhenit’swet,unlikegouache.
That’swhyI usea thinlayerofcasein
foranunderpaintingorprimingcolor,
whichI applyinadvance.I painted Alaskan Wolf (gouache with casein on paper, 5x8) from a taxidermy specimen. I started with black and white casein for the background.
Once I’ve painted a background, I don’t want it to change too much. I chose gouache for the wolf because I wanted to be able to reactivate the paint.
That’s the only way to achieve the appearance of soft fur, especially in shadows, such as those under the mouth and on the neck. To create that soft
look, I rewet a postage-stamp-sized area using a fl at brush dipped in pure water—really quick, no scrubbing. I can gently coax out softness using
another brush or my fi nger, or I can drop in a stroke that will blend into a blur. In the areas in which I wanted fi ne details of fur in the lights and
halftones, I applied gouache with a drybrush technique. I fi nished with a few touches of light-and-dark-value watercolor pencils.Instead of painting a standard garden vista, for Cinnamon Ferns (gouache over casein on paper,
5x8), I decided to unravel the complicated rhythms of a bank of the backlit plants. I’d already primed
a page in my sketchbook with casein in a color referred to as “vegetable green” or “parent green.”
This is the standard hue of the transmitted light that fi lters through new grass or spring foliage.
My intention was to cover up most of the underpainting, but allow some areas to peek through.