Application guide

Resin for Spray-Up Process

Spray-up production needs a resin that atomises cleanly through spray equipment and gels on a predictable schedule.

Full control over gel timing at scale.

Spray-up speeds up FRP fabrication by depositing chopped glass roving and catalysed resin onto the mould together, through a chopper gun, instead of laying reinforcement by hand and wetting it out separately. It suits fabricators producing larger volumes of moderately complex parts — tanks, tubs, panels and similar shapes — where the labour savings over hand lay-up matter, provided the resin sprays cleanly and gels on a schedule the production line can work around.

What manufacturers build

Spray-up is used for products where higher-volume production and moderate part complexity make chopper-gun application worthwhile — water tanks, bathtubs and sanitaryware, panels, cooling tower components and similar moulded shapes with large surface areas benefit most from the process's speed advantage over manual lay-up.

Why this material suits the work

Spray-up puts different demands on a resin than hand lay-up — it needs to atomise cleanly through spray equipment without clogging, and its gel time has to be predictable enough for an operator to build up thickness across a mould without the first pass gelling before the last one is sprayed. GP Clear Resin's 350–450 cPs viscosity is compatible with standard spray-up equipment, and because it's a non-accelerated resin, fabricators can dose the accelerator to set the gel time that best matches their equipment's spray rate and mould size.

Required resin characteristics

A viscosity compatible with chopper-gun atomisation without clogging equipment
Predictable gel timing that can be tuned to the spray rate and size of the mould
Even resin distribution alongside chopped roving as it's deposited on the mould
Reliable mechanical strength once the sprayed laminate is compacted and cured
Consistent behaviour across repeated spray cycles in a production run

Process context

In spray-up, resin catalysed with an MEKP hardener and cobalt octoate accelerator is fed through a chopper gun alongside continuous glass roving, which is cut and deposited onto the mould simultaneously with the resin spray. The sprayed laminate is then compacted with a roller to remove air and ensure the resin has fully wet out the chopped glass fibre, in the same way a hand-applied layer would be rolled. Multiple passes build up the required thickness before the part cures at room temperature and is released from the mould.

Advantages

Compatible viscosity for clean atomisation through standard spray-up equipment
Non-accelerated cure system lets fabricators dial in gel time to match spray rate and mould size
Sub-8-minute gel time supports faster cycle times than hand lay-up on larger parts
Consistent 99% purity maintains laminate quality across high-volume spray production

Common products

Water tanks and sanitaryware produced at volume
Bathtubs and moulded bathroom fixtures
Cooling tower panels and casings
General FRP panels with large surface areas

Common questions

Is GP Clear Resin compatible with chopper-gun spray-up equipment?

Yes, its viscosity is compatible with standard spray-up equipment. As with any resin, operators should check compatibility with their specific spray equipment setup and adjust accelerator dosage to suit.

How does gel time control work in spray-up compared to hand lay-up?

Because spray-up deposits resin and reinforcement faster than hand lay-up, gel time is tuned to the operator's spray rate and the mould's size — enough time to complete all passes and roll out air, but not so long that production slows unnecessarily.

Does spray-up use the same reinforcement as hand lay-up?

Spray-up uses continuous glass roving fed through the chopper gun and cut on application, rather than pre-cut chopped strand mat — but the resin's role in wetting out that reinforcement is the same.

How is GP Clear Resin catalysed for spray-up production?

It is cured at room temperature with an MEKP catalyst (around 1.5%) and a cobalt octoate accelerator (around 0.4%), with dosage adjusted to the operator's spray rate and the equipment being used.

Is spray-up or hand lay-up better for my production?

Spray-up generally suits higher-volume production of moderately complex shapes where labour savings matter most; hand lay-up gives more control for complex geometries or lower-volume work. Both use the same GP Clear Resin.

Need resin for your spray-up production?

Get a bulk quote or talk to our technical team about the right grade and dosage for your spray-up process.

Contact Samrat FRP Traders