Grumbacher Slow-Drying Medium II for Oil Paintings is ideal for use when one wishes to slow drying time and is especially useful for alla prima (wet-in-wet) techniques. It imparts a high gloss when dry. For best results, add to colors in small amounts until the consistency desired is obtained. Only dilute with turpentine or Grumtine – petroleum based solvents and odorless paint thinners are not compatible with this product. Use in a well ventilated area. Made in USA.