Spray Lay-up

Description
Fibre is chopped in a hand-held gun and fed into a spray of catalysed resin directed at the mould. The deposited materials are left to cure under standard atmospheric conditions.

Materials Options:
Resins: Primarily polyester.
Fibres: Glass roving only.
Cores: None. These have to be incorporated separately.

Main Advantages:
i) Widely used for many years.
ii) Low cost way of quickly depositing fibre and resin.
iii) Low cost tooling.

Main Disadvantages:
i) Laminates tend to be very resin-rich and therefore excessively heavy.
ii) Only short fibres are incorporated which severely limits the mechanical properties of the laminate.
iii) Resins need to be low in viscosity to be sprayable. This generally compromises their mechanical/thermal properties.
iv) The high styrene contents of spray lay-up resins generally means that they have the potential to be more harmful and their lower viscosity means that they have an increased tendency to penetrate clothing etc.
(v) Limiting airborne styrene concentrations to legislated levels is becoming increasingly difficult.

Typical Applications:
Simple enclosures, lightly loaded structural panels, e.g. caravan bodies, truck fairings, bathtubs, shower trays, some small dinghies.

David Cripps, Gurit