Schmincke Onetz Watercolour Medium can be used to modify the working characteristics of your watercolour paints. Onetz is a natural, thickened Oxgall wetting agent, designed to improve the flow of your watercolour or gouache colours. It will decrease the surface tension of your colours when diluted with water. A little of this medium goes a long way, so it should be used sparingly.
Available in a 5ml or 15ml tube