This NSP Chavant Clay is a professional sculpting clay. NSP stands for Non-Sulphurated Plasteline-- what's great about NSP is it eliminates the sulpher filler in professional-grade sculpting clay, which often causes inhibition problems with liquid rubber mould-making materials.  Comes in two options, medium or soft.

To use, simply use small amounts of water, turpentine or mineral spirits as a lubricant on the surface of the clay, which help to keep a smooth surface when handling the clay. NSP can also be melted and poured-- the melting point is approximately 175°F / 80°C.