Using Smooth-On's exclusive "V-Polymer" technology, VytaFlex® urethane rubbers offer superior physical and performance properties. VytaFlex® urethanes feature convenient one-to-one by volume mix ratios. Vacuum degassing is not necessary and VytaFlex® rubbers cure with negligible shrinkage to a durable rubber that will last in production. VytaFlex® mold rubbers work especially well for casting pigmented / colored concrete. Molds made with VytaFlex® Series urethanes will render accurate and uniform colored castings.