Working Tips

• Use a brush or polyester roller to cover the mould surface evenly with gelcoat. Wait for at least an hour until the gelcoat becomes tacky (it will feel slightly sticky but will not actually adhere to the touch) and make sure there are no corners or crevices where the gelcoat is still wet

• Catalyse a working quantity of resin. Polyester resin is usually blue and when properly catalysed changes colour to opaque in 3-5 minutes. Blue streaks indicate poor mixing. Paint the resin over the gelcoat
• Lay down a piece of glass fibre and push it gently into the wet resin with a brush. If using chopped strand mat, use a stippling action - DO NOT 'paint' to and fro as this tends to separate the glass fibres. Make sure the glass fibre is thoroughly impregnated with resin (keep the brush well loaded to add more resin if necessary). When the fibres are properly wetted out they should go clear. Any white patches remaining are dry spots.

• Once completely 'wetted-out', use a metal laminating roller to consolidate the layer and force out air bubbles. This also forces resin through the fibres from beneath which makes for better impregnation.

• A further coat of resin and another layer of glass fibre can then be added, repeating the process. Any number of layers can be built up depending on the thickness and strength required. For many jobs, two layers will be adequate.
• The exposed surface of a chopped strand mat laminate will be rather rough - this will not normally matter, but if necessary it can be covered with a layer of surface tissue. Surface tissue is fine glass fibre material - it has a smooth side and a 'hairy' side. While the laminate is still wet, apply the surface tissue 'hairy' side down, wet out with more resin and stipple down lightly.
• When the required layers have been built up, leave the laminate to cure. It will soon reach the 'green' stage when it becomes quite firm, at which point you can trim off rough edges with a trimming knife. Once fully hardened you will have to use a hacksaw with a metal cutting blade. Cutting, sanding and drilling cured laminates produces harmful particles - to avoid these you should wear a breathing mask and goggles.

• When fully cured, the laminate can be released from the mould.

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Fibreglass Developments Ltd

25-29 Mahinui Street, PO Box 391, Feilding,

New Zealand.

Telephone: +64 6 323 0960 Fax: +64 6 323 0973 Email: info@composites.co.nz