Gamsol is the safest solvent that allows oil painters to utilize all traditional painting techniques without compromise. Thinning oil colors. A little goes a long way; stiff oil colors relax immediately when a little Gamsol is added. Be careful not to thin oil colors too much with solvent alone, this can compromise the ability of the paint to form a paint film. Modifying painting mediums. Galkyd line of painting mediums are formulated with Gamsol. Studio clean up -Brushes, palettes, palette knives, etc. Note - Gamsol should not be added to painting mediums made with natural resins (dammar, copal, mastic). They require strong solvents such as turpentine.