Graham Oils use only the finest vehicle, Walnut Oil to make some of the finest oil paints on the market! Walnut oil provides a "unique refractive index" and will not yellow over time, which allows for incredible paint brilliance. Walnut oil's unique body allows for an increased amount of pigment suspension in comparison with other oils, giving their paint higher color saturation and tinting strength, as a result. Manufactured with only the finest example of each available pigment source, their paints contain no fillers, extenders, or adulterants, which have negative effects on color and how the eye perceives it. Hand-crafted in small batches, attention is paid to adapting manufacturing processes to specific pigment "personalities" and requirements. Use of proper milling pressure for each pigment helps to achieve optimum pigment load and dispersion. Artists run the Quality Control Department at M. Graham, assuring the quality of everything they manufacture. A green company, their products and manufacturing is solvent-free. Green-minded artists can finally enjoy painting with high-end, professional quality oils, from an environmentally conscious company!