Basic Fibreglass Laminating Guide
This guide provides a basic overview of the hand-lay-up process for producing a fibreglass laminate in a prepared mould. Materials, catalyst ratios, working times and curing requirements vary, so always follow the product manufacturer’s technical and safety instructions.
Before you begin
Have your materials and equipment ready before mixing the resin. Work in a well-ventilated area and wear suitable gloves, eye protection and respiratory protection. Always follow the resin and catalyst manufacturer’s technical and safety instructions, including the specified mixing ratio, working time and curing conditions.
1. Apply the gelcoat
Using a brush or polyester roller, apply an even layer of gelcoat over the prepared mould surface. Allow it to reach the recommended tack stage before laminating, checking that no wet gelcoat remains in corners or recesses.
2. Prepare the resin
Measure and catalyse a suitable working quantity of resin in accordance with the manufacturer’s instructions. Mix thoroughly, scraping the sides and bottom of the container to ensure the catalyst is evenly dispersed, then apply resin over the gelcoat.
3. Apply the glass fibre
Position the glass fibre over the wet resin and gently work it into place with a brush. When using chopped strand mat, use a stippling motion rather than brushing backwards and forwards, as this can disturb and separate the fibres. Add resin as required until the reinforcement is fully wetted out and no dry, white areas remain.
4. Consolidate the laminate
Use a metal laminating roller to consolidate the layer, distribute the resin evenly and remove trapped air. Pay particular attention to corners, curves and detailed areas where air pockets can form.
5. Build the required thickness
Apply additional resin and layers of glass fibre as required, repeating the wetting-out and consolidation process for each layer. The number and type of reinforcement layers will depend on the required thickness, strength and intended use of the finished component.
6. Apply surface tissue if required
The exposed surface of a chopped strand mat laminate will normally have a textured finish. If a smoother back surface is required, apply surface tissue while the laminate is still wet. Position it with the softer, “hairy” side against the laminate, wet it out with resin and stipple it down gently.
7. Allow the laminate to cure and trim
Leave the completed laminate to cure. Once it reaches the firm but not fully hardened “green” stage, rough edges can generally be trimmed more easily. Fully cured fibreglass will require suitable cutting or sanding equipment. Always wear appropriate eye, skin and respiratory protection when cutting, drilling or sanding composite materials.
8. Release the component
Once the laminate has cured sufficiently, carefully release the finished component from the mould.
