Williamsburg Iridescent Colors are colorfast and permanent. We make these with ground mica so that even the "metallic" colors will not tarnish. There are some limitations inherent in the composition of these colors: in order to refract light and appear metallic or nacreous, the mica particles must not be ground too small. They should be almost like tiny crystalline prisms sparkling with glints of light. Because of this the paint has a semi-translucent quality - not the heavy covering power of aluminum radiator paint.