Linseed oil
Linseed oil is an oil derived from the seeds of the flax plant. It is a type of drying oil--that is, it takes in oxygen from the air to form a tough film that resists breaking, chipping, and changes in the weather. Linseed oil is used primarily in printing inks, paints, varnishes, linoleum, and other industrial products. In addition, it is sometimes used as a protective treatment for concrete.