Dr Ph Martin’s Hydrus Liquid Watercolours made from the finest artist pigment – chosen for extreme light fastness and brilliance. Dr Ph Martin’s Hydrus Liquid Watercolours is a lightfast, transparent watercolour ink which delivers the same brilliant, permanent colours as traditional watercolours. Dr Ph Martin’s Hydrus Liquid Watercolours are manufactured from the finest artists pigment. The range of colours offer freedom of bleeding and intermixing whilst maintaining the transparency and luminosity of the colour. Suitable for use with for calligraphy technical pens, fountain pens and airbrushes. For opaque gouache effects, titanium white can be mixed, which gives pastel effects.