The more significant volume of unsaturated polyester resins are used in fiberglass reinforced plastics, but they also find some applications in coatings and lining materials. The important characteristics of unsaturated polyester systems in coatings are high hardness, high gloss, rapid setting, low volatile content (reactive diluent) and high build capacity. Their low flexibility and high volume shrinkage may result in poor adhesion in the absence of good surface preparation or suitable primers. They also have very good chemical resistance.
In coatings, one of the main applications of unsaturated polyester resins is in furniture and wood finishes. They are also used in gel coats for boats and bathroom fixtures. Another important area of application is in automotive fillers and putties. Unsaturated polyesters are also widely used in chemical resistant coatings and linings for chemical and petrochemical storage tanks.