Polyesterplaster

Polyesterplaster is a plaster-like composite used for coatings, repairs, and decorative work. It combines unsaturated polyester resin with mineral fillers, pigments, and sometimes reinforcing fibers. The resin binds the fillers into a rigid, lightweight mass, and additives such as fiberglass may improve tensile strength where needed. The formulation is designed to cure at ambient temperatures to produce a surface that can be formed, finished, and painted much like traditional plasters.

Curing occurs through a polymerization reaction initiated by a catalyst. The process is exothermic and has a limited working time, requiring careful timing and ventilation. Application is typically by trowel, casting, or patching, followed by sanding and sealing. Polyesterplaster adheres to prepared substrates such as concrete, brick, and wood, and with proper surface preparation it can be used for repairs, decorative plastering, molds, and castings. It is also used in marine, automotive, and sculpture contexts for repair fills and decorative elements.

Compared with cementitious plasters, polyesterplaster offers faster cure, lighter weight, and a smoother, more uniform surface with good dimensional stability and water resistance. Limitations include brittleness relative to cement-based finishes, sensitivity to heat during curing, and the need for adequate ventilation due to volatile components. It is less breathable than some traditional plasters and may not accommodate substantial substrate movement without cracking. Proper surface preparation and compatible finishing products are important for long-term performance.