Winsor and Newton Artists Watercolour 5ml Cobalt Violet Series 4Winsor & Newton Artists Water Colours are individually formulated, using the finest pigments available in the highest concentrations possible. The high performance pigments ensure excellent strength and brilliance of colour. The wide range of colours allows all artists to choose a palette to suit their needs. Use 5ml or 14ml tubes when using large quantities of colour. You\'ll find Artists Water Colour half pans more suitable for outdoor sketching and using smaller quantities of colour.