This 6" x 3 1/2" casein practice painting was done in thin washes on 140 lb. Arches watercolor paper. The colors used were Ultramarine Blue Deep, Shiva Rose, Burnt Sienna, Yelow Ochre, Cadmium Yellow Light and, Titanium White. I have shaky hands so the lettering wobbles and bobbles a bit.
Since casein becomes very hard when dry, this watercolor paper would need to be mounted on a firm surface and, varnished.