These two high quality additives from Winsor & Newton's Artists' Acrylic Mediums range allow better control of flow and drying time.Artists' Acrylic Flow Improver increases the flow of acrylic colours, allowing the application of areas of flat, even colour without changing colour strength.It is also effective for hard edge painting techniques.It maintains the stability of the colour and slightly slows drying.This medium maintains no colour shift from wet to dry when used with Winsor & Newton Artists' Acrylic.Winsor & Newton Artists' Acrylic Slow Drying Medium slows the drying time of acrylic colour to give you more working time of colour for extended blending and manipulation.A ratio of 1:1 volume doubles the drying time (mix with colour up to 1:1).It maintains colour viscosity and has no effect on the finished colour when dry.This medium maintains no colour shift from wet to dry when used with Winsor & Newton Artists' Acrylic.