Oxgall

Semi-transparent liquid obtained from the gall bladders of cattle and used as a wetting agent in watercolor. Oxgall, or ox bile, contains sodium choleate salts (taurochloate and glycochloate) with some cholesterol, lecithin, and other natural products. Oxgall is dried and powdered, then mixed with water or ethanol for use. It is an effective natural wetting agent that is used with watercolor paints to facilitate flow. Oxgall has also been used in marbling, engraving, lithography, and textile dyeing. It has been used as a plasticizer in glue-paste mixtures.