Glass mat
The glass mat (chopped strand mat) is the most commonly used reinforcement material when processing polyester by the hand lay-up method. The short pieces of glass fibre lie criss-crossed by and on top of each other and are glued together by a binder. Both powder-bonded and emulsion-bonded glass mat exists. for more info, see; https://www.v-sure.eu/en/products/fibre-reinforcement/glass-mat/