Cleaning - Fisheries KnO 100378_Fibreglass boat building

Fibreglass boats

Practical Action

Cleaning

Files, drills, saw blades and discs can be cleaned with acetone when clogged. If left overnight

the resin will harden and render the tool useless.

Trimming

The easiest stage to trim is just after the resin has set, when the moulding is rubbery and can

be cut with a sharp knife. A large moulding must be trimmed in stages as each layer sets. The

rubbery “gel” stage lasts only about thirty minutes depending on the type of resin used. Do

not trim too soon as the laminate will not have set enough and will be disturbed.

Sealing edges

All Fibreglass working will leave a rough, shattered edge where water can penetrate and

eventually cause de-lamination. All such edges must be sealed either with resin painted on or

bonded over when assembling. Holes for deck and underwater fittings should be treated

carefully in the same manner. If possible work from the gel coat face and support the inside

with a wooden pad. Seal the hole edges thoroughly.

Care of moulds

The mould must be kept in excellent condition for re-use. Between mouldings it should be

checked for damage and receive a coat of wax. Every five to ten cycles, the mould should be

thoroughly checked and any repairs carried out to wear on flange boltholes, or damage caused

by hammering during release. Wax can build up in some areas to form a thick layer, which

gives a dull gel coat, this should be washed or polished off. The inside surfaces should be

kept as smooth and polished as possible. If unused for a long period, the mould must be

stored under cover. Exposure to the sun and wind will dull the shiny gel coat surface. Small

moulds can be turned over or covered with a dustsheet.

General precautions

Fire hazard

Catalyst and accelerator, when mixed directly, form an explosive mixture. They are also highly

flammable. Smoking in working areas must be totally forbidden. Great care must be taken to

mix the correct amount of catalyst to the resin to avoid a “Hot mix” which could produce so

much heat that it self-ignites. Any bucket of resin producing smoke should be immediately

taken outside the moulding shop and filled with water. Any spillage should also be diluted

with water.

Health hazard

All these materials are toxic if swallowed. Special care should be taken with catalyst, as it will

cause burns to skin and possibly blindness if in contact with the eye. Fire extinguishers of the

correct type, patent eyewash and a First Aid Kit should be readily available. Facemasks must

be worn when laminating in confined areas and when grinding or sanding cured laminates.