Solid Solutions Acrylic Colour is a high-quality acrylic paint which is renowned for its exceptionally smooth consistency. It is a thick buttery consistency that is quick-drying, water-repellent, flexible and non-toxic. Clean up with soapy water. Colours may stain, always wear protective clothing. Conforms to ASTM D-4236. Colour Burnt Sienna Pigment Number PBr7 Pigment Lightfastness Rating ASTM1 Paint Opacity Semi-Transparent Derived from the burning of raw sienna, Burnt Sienna is a rich, warm brown colour. Sienna, a natural yellow clay found in the earth, deepens in colour when subjected to heat. Among the oldest pigments, it traces its roots to prehistoric cave art. Named after Siena in Italy, where it was sourced during the Renaissance, Burnt Sienna is an opaque colour with red-brown tones.