This is the Art Treehouse Impasto Medium, developed and tested for use with palette knives and stiffer brushes. It comes in a 4 oz. jar for easy access. Impasto Medium is a very thick paste. It can be mixed with Biobased Artist Thinner, Walnut Oil, Linseed Oil, or Oil of Spike Lavender so that it will flow with the brush during the stroke, yet set up stiff for drying. Use of this medium allows for free creative expression on the part of the artist, but prevents the paint from running down the canvas when thick amounts are applied. Water-Washed Walnut Oil is used in this medium, resulting in the least yellowing and the brightest colors. There are no alkyds, stearates, resins, driers, or petroleum-based solvents used. Calcium carbonate, silica, and the mineral baryte give Impasto Medium its firmness and stability. A unique recipe!