Pre-tested is Grumbacher’s professional line of conventional oil colors which offers the finest pigments milled in select alkali-refined linseed oil. Grumbacher Pre-tested Oils provide high chroma, superior tinting strength, and excellent adhesion for the professional artist. There are 90 oil paint colors available within the line. Grumbacher specifies only the best ingredients that are available, putting every new color through a rigorous selection process. Pre-tested is not only the name but also the philosophy of the way Grumbacher manufacturers each and every one of their products. Find the very finest quality oil paints available in each tube of Grumbacher Pre-tested oils and add them to your personal oil paint art supply.