Products bearing the AP seal of the Art & Creative Materials Institute, Inc. (ACMI) are certified non-toxic. A product can be certified non-toxic only if it contains no materials in sufficient quantities to be toxic or injurious to humans, or to cause acute or chronic health problems.
This is a natural wetting agent for degreasing of undercoats before painting with watercolors or gouache. It should be used sparingly, and is suitable as a leveling agent for watercolors. Oxgall tends to flocculate (form lumpy or fluffy masses) when stored over long periods of time. However, this does not effect the quality or application method of the product.