Poly-resin, or polyester resin, is the one of the most commonly used moldable plastics. One of the advantages of pure poly-resin is that it can be made into items that are crystal clear, or colored by dyes to produce jewel-like items. Poly-resin can be poured like water then cured from a liquid to a solid state.
There is a range of polyester resins made from a variety of different glycols, acids and monomers. There are, however, two basic types used as laminates in the composites industry: orthophtalic polyester resins and isophthalic polyester resins. Because of their superior water-resistant properties, the isophthalic poly-resins are becoming popular in industries producing marine products. The majority of polyester resins are pale colored and viscous liquids in which a polyester has been dissolved in a monomer, such as styrene. To be used in molding, poly-resins require the use of ancillary products such as catalysts, accelerators and additives, such as a pigment or a fire-resistant substance.