Polyurethane (Smooth-Cast 383 & 385)

This mustard-yellow polymer is a mixture of two polyurethane resins - one commonly used for industrial tooling and a mineral-filled urethane casting resin. The mineral additives make it very hard and durable, and its resin matrix means it can be cast without specialist machinery to make prototypes that can be used in demanding applications: it can be machined, drilled and sanded. Regardless of the end-product or even type of polyurethane you are using, the way in which you use polyurethane resins is always the same: the raw materials come in two parts, a liquid isocyanate (a very reactive chemical derived from petroleum) and a polyol (a long-chain alcohol), which are mixed to a specified ratio to create a reacting liquid, which is then poured into a mould or onto a surface and left until it cures to form a solid object.