Hydrus Fine Art Watercolor is liquid watercolor that delivers the same brilliance and permanency of traditional watercolor that one finds in a tube. All colors are Lightfast, Transparent, Brilliant, Permanent Pigment, Blendable, Intermixable, Hi-Density, AP approved non-toxic, and Conforms to ASTM Standard D4236. Where work requiring transparency is needed, Hydrus can be used in Technical Pens, Calligraphy Fountain Pens, and Airbrushes. Titanium White can be intermixed with colors to achieve an opaque gouache watercolor and beautiful pastel shades. Sold in 1 oz. bottles with dropper caps.