PRINCETON ART & BRUSH-Catalyst Silicone Wedge Tool. This tool is not quite a brush or a palette knife. It is crafted of flexible silicone to allow artists a new form of expression. It is designed for use with heavy body paints, oils, acrylics, and water-mixable oils. Can also be used with clay, plaster or even food crafting. It is made of FDA approved silicone. Silicone is easy to wipe clean and is solvent-resistant. Clean up in most cases can be done with mild soap and water.