Fibreglass Materials, Tools & Equipment

Fibreglass work requires materials that are compatible with one another and equipment suited to the selected manufacturing process. The following overview covers the materials and tools commonly used for basic laminating, moulding and repair work.

Always read the manufacturer’s technical data sheet and safety data sheet before using any resin, catalyst, hardener, additive or cleaning product. Mixing ratios, working times, application requirements and safety precautions vary between products.

Materials

Laminating Resins

Polyester resin is commonly used for general-purpose fibreglass laminating, moulding and repair work. Vinyl ester and epoxy resins may be selected where different mechanical properties, chemical resistance, adhesion or processing characteristics are required.

The correct resin will depend on the reinforcement, moulding process, finished application and working conditions. Products intended for laminating, casting, tooling or surface coating are formulated differently and should not be substituted without checking their suitability.

Catalysts & Hardeners

Polyester resin generally requires a measured quantity of MEKP to initiate curing, while epoxy systems use a resin and hardener supplied as a matched system.

The specified mixing ratio must be followed accurately. Too much or too little catalyst or hardener can affect the working time, cure and performance of the finished laminate. Never estimate the quantity or combine components from different resin systems.

MEKP and other curing agents can be hazardous. Handle, measure and store them only as directed by the manufacturer.

Gelcoat & Topcoat

Gelcoat provides the smooth, coloured surface found on many moulded fibreglass products. It is normally applied to the prepared mould before the structural laminate is added.

Topcoat or flowcoat is formulated for application to an exposed surface and is commonly used to finish the reverse side of a laminate or complete certain repairs. Gelcoats and topcoats are available in a wide range of colours and formulations for different service conditions.

Glass Fibre Reinforcements

Glass fibre reinforcement provides much of the strength within a fibreglass laminate. Common forms include chopped strand mat, woven fabrics and stitched reinforcements.

Chopped strand mat conforms readily to curves and is widely used for general laminating. Woven and stitched materials can provide greater directional strength and may be combined with other reinforcements to achieve the required laminate properties.

The reinforcement must be compatible with the selected resin system and suitable for the component’s shape, loading and manufacturing process.

Release Agents

Release agents prevent the cured laminate from bonding permanently to the mould. Common systems include release waxes, liquid release films and semi-permanent release products.

The most suitable release system depends on the mould surface, resin, required finish and anticipated production quantity. A new or repaired mould may require several preparation stages before it is ready for laminating.

Fillers & Fairing Compounds

Fillers can be combined with compatible resin systems to alter viscosity, reduce density, form radiused corners or create filling and fairing compounds.

Different fillers produce different handling, strength and sanding characteristics. The selected filler and mixing quantity should suit both the resin and the intended use. A general filling compound should not be assumed to provide structural reinforcement.

Inert fillers can be added to resin to produce a general-purpose body filler stopper paste, or to make a slurry for resin casting. They are not usually needed for many laminating projects but it is very common to use fillers for casting projects. Two common fillers are calcium carbonate and Q-Cels. However, Q-Cels are normally used in conjunction with epoxy resin to make a coving filler in right angle corners and for ease of sanding.

Pigments & Additives

Compatible pigment pastes can be added to some resins, gelcoats and topcoats to produce the required colour. Excess pigment or an incompatible product may interfere with curing or reduce performance, so the manufacturer’s recommended addition rate should be followed.

Other additives may be used to modify surface cure, fire performance, ultraviolet resistance, flow or processing characteristics. They should only be added where approved for the selected resin system.

Core Materials

Core materials increase the stiffness and thickness of a component without requiring a heavy solid laminate. Common options include structural foams, balsa, core mat and honeycomb materials.

Selection depends on the required strength, weight, temperature resistance, moisture exposure and manufacturing process. The core must be properly bonded and protected from water entry where necessary.

Specialist Materials

Specialist resin systems and reinforcements are available for applications requiring properties such as increased stiffness, impact resistance, reduced weight, fire performance or chemical resistance.

These may include carbon fibre, aramid fibre, vinyl ester resin and specialist fire-retardant or chemical-resistant systems. Their processing requirements can differ significantly from standard polyester and glass fibre materials, so appropriate technical advice should be obtained before use.

Tools & Equipment

Measuring & Mixing Equipment

Use clean, dry containers that are chemically compatible with the selected resin system. Purpose-made graduated mixing containers, accurate scales and dedicated catalyst dispensers help ensure that components are measured correctly.

Use clean mixing sticks or suitable mechanical mixing equipment and stir thoroughly, including around the sides and bottom of the container. Avoid food containers and containers made from unidentified plastics, as some materials may soften, dissolve or contaminate the resin.

Brushes & Applicators

Suitable brushes and rollers are used to apply resin, gelcoat and other surface coatings. Tools made specifically for fibreglass work are preferable, as adhesives, coatings and plastics used in ordinary decorating equipment may not be compatible with the resin.

Keep separate applicators for different products to prevent contamination.

Laminating Rollers

Laminating rollers consolidate the reinforcement, distribute resin and remove trapped air. They are available in different materials, shapes and sizes for use on flat surfaces, curves and detailed areas.

A laminating roller is different from a conventional paint roller and should be selected to suit the reinforcement and shape being laminated.

Cutting & Preparation Tools

Prepare reinforcement before mixing the resin. Suitable scissors, knives and cutting tools should be kept clean and sharp to prevent distortion or contamination of the material.

Surface preparation may require scrapers, grinders or abrasive equipment. Remove loose or damaged material and ensure that the prepared surface is clean, dry and appropriately abraded before laminating begins.

Sanding & Finishing Equipment

Cured fibreglass can be shaped and finished using suitable abrasives, sanding equipment and polishing systems. Dust extraction should be used wherever practicable.

Cutting, grinding and sanding composite materials can create hazardous dust and exposed fibres. Wear appropriate eye, skin and respiratory protection and keep the work area clean.

Personal Protective Equipment

Required protective equipment will depend on the products and processes being used. It may include chemical-resistant gloves, protective clothing, safety glasses or goggles and suitable respiratory protection.

Work in a well-ventilated area and keep resin, catalyst, solvents and other hazardous products away from heat, sparks and ignition sources. The relevant safety data sheets should be available before work begins.

Cleaning & Disposal

Use cleaning products recommended by the material supplier and avoid unnecessary solvent use. Never use acetone or other solvents to clean resin from your skin.

Do not pour resin, catalyst, solvents or contaminated cleaning liquids into drains. Store and dispose of unused products, cured waste and contaminated materials in accordance with their safety instructions and applicable disposal requirements.