A thermosetting plastic, also known as a thermoset, is a type of polymer that irreversibly hardens or cures when heated. The starting material for a thermoset is usually a liquid or soft solid that is designed to be molded into the final shape. Once cured, a thermoset cannot be melted for reshaping, unlike thermoplastic polymers which can be melted and reshaped. The curing process is induced by heat or suitable radiation and may be promoted by high pressure, a catalyst, or a hardener. The resulting three-dimensional network of bonds, or crosslinking, makes thermosetting plastics generally stronger than thermoplastic materials. They are also better suited to high-temperature applications up to the decomposition temperature since they keep their shape as strong covalent bonds between polymer chains cannot be broken easily. Examples of thermosetting plastics include Bakelite, epoxy resin, fiberglass, and polyurethane.