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Welcome to CFS Fibreglass

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We’ve compiled this list of FAQs for those looking for a bit more information on what fibreglass is and how it’s used.

For more in-depth information about specific fibreglass applications, please see our Projects and Methods sections.


What is fibreglass?

GRP (Glass Reinforced Plastic) is commonly referred to as fibreglass. It’s made by combining a cloth or matting made up of spun glass fibres with a resin. That then sets to form the tough plastic material that we refer to as fibreglass.

What is fibreglass mainly used for?

Fibreglass is used in many applications, but most commonly it is used in the manufacture of boats and industrial mouldings, for flat roofing applications and even in artwork and sculpture!

Is fibreglass bad for the environment?

Resins are made from oil products and have similar disposal problems as most plastics.

How long does fibreglass last?

It is incredibly durable – its use in the marine trade has shown that GRP can be serviceable for many decades. A correctly installed and maintained fibreglass flat roof could last up to 30 years or more!

What are the advantages and disadvantages of fibreglass?

It is extremely strong for its weight. It does not corrode and is resistant to weather. Items can be manufactured without complicated or expensive machinery or tooling – you just need some basic tools and safety equipment and you’re good to go!

What are the disadvantages of fibreglass roofing?

Although slightly more difficult to apply, it has no disadvantages when compared to a covering like mineral felt or rubber. A fibreglass flat roof will have a far longer service life due to its superior durability, and the fact that it can be easily repaired or refreshed.

Is fibreglass waterproof without topcoat?

If applied correctly yes, but temporarily. The fibres near the surface will eventually absorb some moisture without a protective layer provided by a gelcoat or topcoat. Badly made GRP will have some spaces between fibres which will allow water to pass straight through.

What happens if fibreglass gets wet before it cures?

Water will contaminate polyester resins and prevent them from curing properly. It is important therefore to cover any recently applied fibreglass to protect it from any unexpected wet weather!

How long does fibreglass take to fully cure?

Resin can be manufactured to cure in a variety of speeds – certain applications require a faster or slower cure than others. Cure times are also affected by the amount and type of catalyst used, and the temperature of the curing environment.

What happens if you don’t put enough hardener in fibreglass resin?

If there is not enough catalyst (hardener) added to the resin solution, it will only partially cure, or not cure at all!

Can you fibreglass over fibreglass?

Yes! Fully cured GRP will need simple but thorough surface preparation to allow this, but it is a very common practice.

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