Grumbacher Sun-Thickened Linseed Oil Medium works similarly to traditional linseed oil in terms of adding gloss and fluidity to oil paints. Sun-thickened linseed oil is heavier in body and can be applied directly to paint or used in glaze mediums, clear varnishes and emulsions. It is an extremely flexible medium derived from purified oil and can be pre-diluted with turpentine, Grumtine or Pre-tested odorless thinner. Made in USA.