PPG SigmaDur 520Description PPG SigmaDur 520 (Amercoat 450SG) is a two component, an aliphatic acrylic polyurethane that supplies a decorative finish resistant to splashes of mineral and vegetable oils, paraffins, aliphatic petroleum products and mild chemicals. Used on many areas of marine furniture due to its non chalking, non yellowing properties. Where To Use A durable product that can be used in temperatures down to 5C and has excellent non yellowing properties.