Chopped Strand Mat, also known as fiberglass mat, has short strands of fibers held together with a resin binder. It is affordable and is often used in mold construction and parts where thickness is needed.
Chopped strand mat can easily be used to conform to tight curves and corners. The randomly oriented fibers give parts equal stiffness in all directions. Mat does not add much strength to a part. If strength and thickness are both needed, it is recommended that the chopped strand mat be used in between layers of woven fiberglass fabric. Layering will also help the fabrics bond well together. Mat is NOT compatible with epoxy resin. The binder that holds the short strands together needs styrene to dissolve properly. Styrene is found in polyester and vinyl ester resin. Fiberglass mat will create a higher weight product. If a lower weight is needed, a fiberglass cloth or knitted fabric should be used.