In order to reduce product production costs and improve hardness or other properties (flame retardant, reinforcement, heat resistance, reduction of shrinkage stress and thermal stress), organic or inorganic fillers can be added during the production of certain polyurethane products. Fillers are also called fillers and extenders. Some fillers are also body pigments. Fine fillers have good hiding power and are often used in the coatings industry.

Fillers can be used in a variety of polyurethane products, such as polyurethane coatings, sealants, polyurethane slurries, specialty elastomers, and polyurethane foams.