Martin/ F. Weber Bob Ross Oil Paints are manufactured with care from the finest materials. They are individually evaluated for quality and performance so novices and experienced painters alike can achieve optimum results in the wet-on-wet painting technique. The Bob Ross Technique depends upon a special firm oil paint and a wet surface to work into, to achieve the desired effects. These oil colors are specially formulated for his wet-on-wet painting method. Quality ingredients insure permanence, color intensity and professional results. These packages conform to ASTM D4236, and are made in USA.