Artisan Water Mixable Oil Mediums are additives which alter or enhance the characteristics of Winsor & Newton Artisan Water Mixable Oil Colours. They are used to change the rate of drying, increase gloss, improve flow and provide texture to the paint. The main advantage of Artisan Water Mixable Oil Colours and Mediums is that they are solvent-free yet still give the appearance and application of traditional oil painting techniques.