Fiberglass spray lay-up process

Spray-Up also known as chop method of creating fiberglass objects by spraying short strands of glass out of a pneumatic gun. This method is used often when one side of the finished product is not seen, or when large quantities of a product must be made cheaply and quickly with moderate strength requirements.^[1] Corvette fenders and boat dinghies are commonly manufactured this way.

It is very different from the hand lay-up process. The difference comes from the application of the fibre and resin material to the mould. Spray-up is an open-moulding composites fabrication process where resin and reinforcements are sprayed onto a reusable mould. The resin and glass may be applied separately or simultaneously "chopped" in a combined stream from a chopper gun. Workers roll out the spray-up to compact the laminate. Wood, foam, or other core material may then be added, and a secondary spray-up layer embeds the core between the laminates. The part is then cured, cooled, and removed from the mould.