Zinc White: Most transparent white, slow drying. Zinc is recommended for scumbling and alla prima painting. Impressionists who painted directly like Zinc White for its transparency and slow dry time. But Zinc's slow drying time and brittleness does not make it a good choice for general painting. Pigment: Zinc oxide (PW 4), Vehicle: Alkali refined linseed oil Lightfastness I, SEMI-TRANSPARENT.