1. Area has already been stamped. Thermoplastic is laid on the surface. Material is cut so seams are melted
2. Sand is blown on surface with a hopper gun. Sand acts as a release agent to prevent post stamp template from sticking. Also provides friction.
3. While the thermoplastic is still warm, the area is stamped a 2 nd time with a slightly smaller diameter template. This post stamping give you the nice sharp grout lines.