COST EFFECTIVE
Polyester
General fibreglass laminating, repairs and moulding at the lowest cost.
FIBREGLASS AND COMPOSITE SYSTEMS
The right resin, the right ratio, dispatched today
Polyester, vinyl ester and epoxy systems for laminating, repairs and composite builds — with technical data on every product.
Which resin for your job?
PREMIUM MARINE
Vinyl ester
INSPEC 700, Lloyd's Register marine certified. Corrosion resistant in acidic and alkaline environments; marine and pool rated, HDT 100°C.
CLEAR AND VERSATILE
Epoxy
WEST SYSTEM 105: solvent-free, cures clear, bonds wood, fibreglass and metals. Four hardener speeds from 9-minute fast to extra slow.
FINISH THE SURFACE
Gelcoats and flowcoats
FCB-G gloss flowcoats: industrial weathering resistance, high gloss, water resistant and acetone resistant when cured. Catalyse at 1.5–2.5% MEKP — never below 1% or above 3%.
The short answer
Polyester resin suits general fibreglass laminating at the lowest cost. Vinyl ester (INSPEC 700) adds corrosion resistance for boat building and marine laminates. WEST SYSTEM 105 epoxy is solvent-free, cures clear, and bonds wood, fibreglass and metals with a choice of four hardener speeds. Flowcoats cure with 1.5–2.5% MEKP catalyst; epoxy mixes at a fixed 5:1 or 3:1 resin-to-hardener ratio.
Common questions
How do I calculate the correct catalyst ratio for fibreglass resin?
Catalyst addition depends on the product, so always work from the current technical data sheet. UCCC flowcoats and gelcoats catalyse at 1.5–2.5% MEKP — never below 1% or above 3%, as curing problems and physical defects can result. INSPEC 700 vinyl ester is specified at 2% catalyst at 25°C, with gel time varying by temperature and resin grade. WEST SYSTEM epoxy works differently: it mixes at a fixed 5:1 or 3:1 resin-to-hardener ratio, and the ratio should never be altered to change cure time — choose a faster or slower hardener instead.
How much fibreglass mat or cloth do I need for a repair?
The amount of fibreglass reinforcement required depends on the surface area being repaired, the weight of the material (GSM) and the number of laminate layers. Most fibreglass reinforcement is supplied on rolls approximately 1.27 metres wide, so calculating the required linear metres from the roll can help estimate how much material is needed for the job.
How much resin is required for fibreglass laminating?
Resin consumption varies depending on the reinforcement type and laminating method. In many hand lay-up applications the resin-to-glass ratio is approximately 1:1 by weight, meaning roughly equal amounts of resin and reinforcement are used. Additional resin may be required to account for surface preparation, waste and overlapping laminate layers.
What happens if too much catalyst is added to fibreglass resin?
Adding too much MEKP catalyst can cause the resin to cure too quickly and generate excessive heat during the chemical reaction. This may lead to brittle laminates, surface defects or even resin cracking. Following the recommended catalyst ratios and mixing guidelines provided by the resin manufacturer helps ensure consistent curing and laminate strength.