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How To Repair Fibreglass


Repairing fibreglass damage

Although fibreglass – often referred to as glass reinforced plastic or polymer (GRP) – is an incredibly strong and hard-wearing material, accidents and damage can occur

Luckily, GRP can be effectively repaired in a relatively simple and cost-effective way. Our fibreglass repair guide will take you through the steps to achieve a high-quality and durable repair.

Please note that we do not currently offer products or a service for repairing fibreglass, nor are we able to provide advice on repairs over the phone. This guide is meant for informational purposes and has been put together by our experts, who have over 20 years of experience supplying and fitting safe access GRP products.

Safety when carrying out a fibreglass repair

When working with fibreglass, it’s important to take safety precautions. Contact with fibreglass particles can cause irritation of the eyes, skin and the lungs if they are inhaled.

When working on your fibreglass repair, you should cover your skin by wearing gloves, long sleeves & trousers. You should also wear eye protection and a correctly fitted dust mask or respirator. If large areas are being repaired, also consider using a disposable splashproof suit. Work should always be carried out in a well-ventilated area.

Other important things to consider when repairing fibreglass

It’s always important to follow the manufacturer’s instructions and warnings when mixing resin and working with the fibreglass sheets or any other materials. The information provided with the products you’re using should take priority over any information in this guide or found elsewhere online.

Also consider location and temperature. The resin used to apply the fibreglass sheet will react differently in extreme hot and cold. Avoid attempting to carrying out repairs during a very hot day or when the temperature is below 15 degrees centigrade, as these conditions may adversely affect the curing process.

Materials required for mending fibreglass

For personal protectionsafety goggles for fibreglass repair

For repairs preparation

For the bonding

For the finish

To recap, before getting started ensure you have:

  1. Equipped yourself with the appropriate safety equipment
  2. A suitable dry, warm and ventilated workspace
  3. Read and understood the manufacturer’s directions for the products you are using
  4. All the required materials on hand, as once you mix the resin you will have a limited working time until it sets

Ready? Let’s get started!

Step-by-step guide to repairing fibreglass

Step 1 – Identify the Damage

Find all the damaged areas and inspect them closely. Is the damage confined to a small area of the surface?  If so, this can usually be effectively repaired using either a polyester or epoxy filler.

Once the damage is filled and cured it can then be sanded back to a smooth finish before applying a suitable paint or topcoat.  Or, is the fibreglass cracked, torn, shattered or crushed? As you inspect the damage, first consider if the piece is really worth repairing or should it be replaced entirely?

Look closely at the construction of the fibreglass laminate and see if it has a reinforcing core material, in addition to the glass strand mat on the outer layers. If it does, you’ll need to fill in any damaged core material as well.

Mark the area by drawing an outline on the undamaged surface about an inch (25mm) around from the edge of the damage.

Step 2 – Prepare the Damaged Areas

Remove all the damaged fibreglass and core material. Ensure you have aSanding down fibreglass stable base to apply the repair to. Cut away any loose or torn material.

Next, sand down the fibreglass around the damaged area in a 12:1 taper. Do this carefully to avoid sanding completely through the fibreglass.

Sanding the surface will give the resin a key to adhere to, while the taper will ensure the repair lies as level with the original material as possible and blends seamlessly into it. It will also give you a larger surface area for the resin to bond to.

If the damage is accessible from both sides, you can repeat this from the other side as well.

Once the right taper has been achieved, wipe the surface with a rag soaked in acetone. This will remove the fibreglass dust and any dirt remaining on the surface.  Allow to this to evaporate fully.

If working on a double-sided repair, choose which side you will work on first. Attach a piece of plastic to the other side to prevent the fibreglass sheets from sagging through.

Step 3 – Prepare the Fibreglass Sheets

Measure the size of the damaged area. Cut one sheet of fibreglass the same size as this area. Next, measure the full size of the area you have sanded down and then cut a second fibreglass sheet the size of the entire area.

Next cut several sheets in different increments between these sizes. The total thickness of the sheets should be equal to the thickness of the material you are repairing.

If your fibreglass object has a damaged core material, cut a similar size of replacement core. Alternatively, you can fill the void with loose glass fibres combined with resin. However, it is best practice to use a core material of the same type as the existing one.

Step 4 – Prepare the Resin

Prepare the resin following the manufacturer’s instructions. You should mix a similar weight of resin to the total weight of the fibreglass sheets you have prepared.

Keep in mind that once you mix the resin, you will have limited time before it starts to set (often only about 20 minutes), so it is important to work quickly and avoid mixing too much resin at one time.

To avoid rushing and making mistakes, it is worth doing a test piece first to practice before working on your main repair.

Also make sure to weigh the resin and fibreglass carefully to ensure you don’t mix too much and waste materials.

Step 5 – Apply the RepairEpoxy resin and paintbrush

Paint a layer of resin onto the sanded down area. Apply resin to the smallest fibreglass sheet and layer it across the damaged area.

Repeat the process with the remaining fibreglass layer. Ensure the fibres in each layer are completely soaked with resin and free from air bubbles. Try to align the direction of the fibres in the sheets with the way the fibre is lain in the main piece.

As you work, wipe up any drips of resin quickly with the rag before they set. After all the layers are applied, go over the surface with a paddle roller to remove any air bubbles and smooth down the material.

Leave the resin to set. If you are doing a repair from both sides wait 48hrs before working on the other side. Remove the plastic and repeat the process from the other side.

Step 6 – Inspection

Once the resin has set, inspect the repair. Test it to ensure it can withstand the required force, bear weight and so on.

If your repaired piece fails in these tests, it is best to discard it, as it might become a safety hazard and be no longer fit for purpose.

Step 7 – Finishing touches

Sand down your repair to create a smooth and level surface. Wipe clean, then seal with the topcoat. The topcoat can be pigmented to match the rest of the piece and hide the repair.

Once the topcoat has set, your fibreglass repair is complete!

About Evergrip and our fibreglass repair guide

Our GRP experts have been supplying and installing fibreglass products for over 20 years. The unique attributes of fibreglass make it the perfect solution for a wide range of applications, especially in areas requiring safe access such as anti-slip flooring and tactile paving.

Interested in finding out more about how our products can help you? Please contact our friendly team today to discuss your bespoke requirements.

CALL OUR TEAM ON 01757 212744

Evergrip Limited

Flaxley Road, Selby, North Yorkshire
YO8 4BG United Kingdom

PHONE: 01757 212744
Company Registered Number: 04186772
Registered for VAT Number: GB 773 5346 10

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27th March 2020

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