Grumbacher’s signature line of professional oil color, Pre-tested has been a favorite among American oil painters for generations. High chroma, superior tinting strength, excellent adhesion, outstanding working properties, the utmost lightfastness, and archival permanence are all hallmarks of the Pre-tested brand of paint. Proudly made in America, quality is the key ingredient in every tube of paint. Each color is comprised of pure pigments and refined linseed oil, which is tested several times throughout the manufacturing process. The result is tube after tube of consistently smooth, brilliant color with excellent performance and permanence.