Wet Lay-Up involves hand application of chopped strand mat glass fibres with a resin, which is then consolidated to remove all air cavities to form the laminate.
When a resin (a thick liquid substance which can be in a polyester, vinyl ester or fire retardant format) is added to the glass fibres it becomes a material of exceptional strength and adaptability, which is then activated by a catalyst. The binder on the glass fibre is dissolved by the resin and sets to a hard but brittle solid sheet.
Several layers can be applied until the desired amount of glass fibre is achieved. Once the curing process is finished the composite is complete.
The spray lay-up technique uses a spray gun, to spray pressurised resin and reinforcement in the form of chopped fibres. Generally glass roving is used and is passed through the spray gun where it is chopped. The matrix* and reinforcement are sprayed at the same time.
Spray lay-up is used for lower load carrying parts like small boats, bathtubs, truck fairings. This method can provide high volume of reinforcement in composites and there is practically no part size limitation.
*The Matrix - Usually polyester resin but may be epoxy, polyester, vinyl ester, phenolic resin, unsaturated polyester, polyurethane resin.
Minimal equipment and tooling costs
Products can be produced, high quality, corrosion resistant, to fire retardant spec
Various types of resin can be produced including bespoke polyesters to fit specific requirements
Scope for a wide range of physical and mechanical properties in the laminate
Short lead times for component production
Versatility of design, part shape, size and laminate configuration
Cost competitive for individual items and short runs of complicated designs