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Tools used in Fibreglass (GRP)

Tools and equipment used in the GRP industry


The following guide gives you a rundown of the typical tools and equipment you may need to carry out most aspects of GRP moulding. We cover cutting of cured laminates, cutting of glass fibre, carbons etc, application brushes, application  and consolidating rollers measuring and dispensing, final finishing, and personal protection.


Cutting of cured laminates

One of the most common ways to cut fibreglass is with diamond tipped tools. Router tips, cutting wheels are often available with synthetic diamonds bonded to their edges. Hacksaw blades can be used which are great and you can use a reciprocating saw to speed things up however this is only ideal for low volume production but for high volume the diamond tipped cutters are faster and last longer than hack saw blades as glass fibre is very abrasive and will blunt your blades in no time.

 One good tip if the GRP product you are making is not too thick is to dry trim it with a sharp Stanley knife whilst your product is at its green stage (semi cured not too hard) the blade will usually easily cut through but be careful not to cut into your mould or cut whilst the resin is too soft.

Our diamond tools can be found here https://www.ecfibreglasssupplies.co.uk/diamond-tipped-tools




A picture containing indoor, green, floor, toolDescription automatically generatedCutting of Glass fibre, carbon, kevlar cloths etc

Cutting chopped strand and most fibreglass cloths  is quite easy with most sharp tailoring shears and trimming knives. A stanley knife will cut chopped strand matting and biaxial cloth  but it wont cut most woven cloths as it tends to snag and pull at the weave. For woven fabrics use a good pair of sharp tailoring shears or better still invest in a good pair of composite shears as these tend not to wear down as easy as standard shears. For kevlars you will definitely need specialist shears normal shears or composite shears will not cut through aramid or kevlar  so if buying  kevlar for the fist time buy a pair of kevlar shears.  Carbon will also cut with tailoring shears however carbon is delicate and will easily snag with even slightly blunt shears so go for a pair of carbon shears which have a  more abrasive resistant blade. To make things easier when curring and to avoid any repetative strain injurys from constant cutting especially in high level production it is a good idea to invest in the battery powered hand held recharable cutters, these also have a range of kevlar, glassfibre and carbon blades. For thick glass fibres such as combination matting etc you can also go for a more heavy duty cutter which are  mains powdered  as shown below






For our range of scissors,  knives etc please follow this link https://www.ecfibreglasssupplies.co.uk/tools

Application Brushes

A picture containing tool, brushDescription automatically generatedYou may think that just about any old decorating type brush will do for laying resin, stippling fibreglass etc but in actual fact some brushes are definitely not suitable. For one thing the glues that hold bristles into their metal ferrules may not be resistant to the styrene’s in polyester resin and may not withstand acetone when cleaning. Another problem is the paint they use on the handles tend to dissolve and can stain and contaminate your project not to mention the typical hair loss you get with cheap brushes in any case. It can be quite annoying to have a white laminate on a boat contaminated with loads of black bristles.

 It is best to get a brush specifically designed and tested for laminating, we would recommend our plastic handled laminating brushes for most applications or better still go for our brushes that have the plastic ferrules as these reduce the risk of scratching your mould when gel coating.

If you do require a cheap brush, we do have our disposable wooden handle brush, we can't promise that you will not have the odd bristle loss, but we can assure that the glues used will not disintegrate in the resin or acetone, so you won’t get a huge lump of bristle falling out! The handles are also unpainted.

Another useful brush is the foam brush often used for tipping off paints to give a good finish however we find they are brilliant for applying PVA release agents if applying them by hand. The foam doesn’t apply too much product and leaves a good finish without the lines you would get with a brush.

Our brushes can be found here  https://www.ecfibreglasssupplies.co.uk/brushes



Application rollers    

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For speeding up the application of resins onto matting especially when covering a large area such as maybe a on a boat hull, deck, or a GRP roof it is a good idea to use a solvent resistant roller such as the blue striped nylon rollers we supply.

For the application of topcoats and flowcoat use the velour type as you won’t need the roller to hold as much product and they also give a good finish. Most of our flow coats are for brush application and need to be applied quite liberally to get enough thickness to cure properly however they can be roller applied as long as you add or request us to add extra wax for roller application. velour rollers are also good for applying coats of epoxy as the foam roller that are often recommended do tend to disintegrate of the resin starts to cure and becomes tacky. the velours tend to last a bit longer.  Bothe the nylon and velour will resist quite a few washes in acetone also so you can get away with reusing them if cleaned.





Consolidating rollers

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Once you have applied your fibreglass into your mould or other surface depending on project type and you have wet the matting out with resin you will need to consolidate the layer s and expel any pockets of air. This is where you will need a consolidating roller. These come any many variations, styles, and sizes from the standard paddle roller to the traditional washer roller etc then you have long reach rollers, corner rollers and bristle rollers and rollers made with different materials. Here we will go through some of these types of consolidating rollers using the above numbered picture as a reference.

1.       The bristle roller. This roller is made up of a spring covered in hard nylon bristles. The spring allows the roller to bend and take to most slightly curved surfaces and the bristles helps push the resin through the cloth or matting by opening up the fibres slightly. This roller is quite good for hand laying carbon as eth bristles also help pop some of the large air bubble between the fibres.

2.       The aluminium barrel roller. This roller is made from aluminium making it very easy to clean even if the resin has cured it can be easily cleaned with a wire brush as cured polyester resin tend to not bond too well to aluminium. Also, with its barrel shape it can cope with curved or dish shaped mouldings without bridging like a straight roller would.

3.       Aluminium finned roller. This is a modern adaption of the old traditional washer roller with its continuous ribs running around the radius of the roller rather than straight across like a paddle roller. Being aluminium, it is easy to clean and due to the direction of the ribs it does not tend to spray resin as it rolls so there is less mess.

4.       The washer roller. This is the most traditional and oldest design of paddle roller. A lot of the older generation boat builders and GRP fabricators will ask for this one. It can be easily disassembled, and replacement washers can be added. As the washers can be removed, they can be soaked in acetone cleaned and reinstalled onto the roller head. Also being made of steel washers the extra weight helps with the consolidating.

5.       The steel finned roller. This is pretty much a combination of the aluminium finned and the washer roller. It has the ribs flowing in the same direction as the finned roller but is made of steel so has the weight advantage of the washer roller. However, being steel it isn’t as easy to clean so it is best to wash the roller before the resin cures on it otherwise you will have to strip it down, soak it in acetone overnight and use some elbow grease and a wire brush to clean it.

6.       The aluminium paddle roller. This is the most commonly used roller for GRP work. It is aluminium so really easy to clean. The ribs run the length of the roller head, so it not only consolidates the layer together but also helps push excess resin forward. Although it does produce a lot of spray off so make sure surrounding surface are covered.

7.       PTFE Plastic finned roller. This roller being made from plastic is very easy to clean for both polyester and epoxy even when the resin has cured it will easily peel or chip off

8.       The aluminium radius or known as the corner roller. Basically, this roller is for getting into radiused corners of your mould helping to expel those stubborn air pockets that can be tricky to remove in corners. Also being aluminium, it is easy to clean even if polyester resin has cured on it, simply soak in acetone overnight and use a wire brush to remove the resin.

9.       The PTFE plastic radius roller. Much the same as the above aluminium version but being PTFE plastic is also easy to clean even if used with epoxy resin.

10.   Heavy duty aluminium paddle roller.  This is quite a heavy roller head which attaches to most screw fit decorating poles. It is the perfect weight and size for rolling big flat areas such as on boat decks and GRP roofs. Being aluminium, it is easy to clean.

All these rollers can be found here:- https://www.ecfibreglasssupplies.co.uk/laminating-rollers  and also for the application roller click here https://www.ecfibreglasssupplies.co.uk/resin-topcoat-rollers


Measuring and dispensing

when using resins, Gelcoats, filler, bonding pastes, pigments, and other additives it is very important to get the dosages correct. Quite often as users become more confident with the materials, they will quite often guess how much catalyst to put in or how much filler powder to add etc. In most cases Guessing the amount of catalyst to say a polyester resin will work as polyesters tend to be the most forgiving and will generally still cure with even as low as a 1% dosage at normal room temperature. However, this can lead to other issues such as resin taking to long to cure on top if gelcoats for example and causing issues such as wrinkling of the gelcoat etc. you can also add too much and end up reducing the pot life causing the resin to go off whilst you are using it. some resins you just can’t guess with such as epoxies. Epoxies tend to have a specific dosage and adding too little or too much can result in the product not curing at all.  

We offer a wide range of measuring and mixing equipment such as catalyst dispensers which is a bottle that will hold your catalyst or even other chemicals such as styrene, accelerator, and MW. Once the bottle is filled you can use the very handy calibrated spout attached to measure your liquid, as you squeeze the bottle, the liquid fills this spout and stays in the spout even when you release pressure ready for dispensing into your resin or gelcoat.

We also syringe and pipettes for small measuring which are ideal if you are a low volume user

Then for factories and workshops who produce GRP on a larger scale we can also supply wall mounted dispensers as shown below that feed directly from a 25ltr keg.








Some products may require you to measure by weight, so we also have digital scales available, always check the mix ratio of your product and this will tell you whether or not the mix ratio is by weight or volume. If a product for example states to mix A+B at 2:1 by weight and you mix it 2:1 by volume instead, you could find that the two components are of a different density therefore you end up with an uncured mix due to too much of part A or B or even if it does work you could  run out of part A or B due to using up too much of one or the other.

For Mixing this is usually quite simple, you just need something to stir your resin and additives together and, in most instances, you just need a mixing stick. We have a wide range of these from the most popular small dental tongue depressor types ideal for small mixes up to the larger wooden mixing sticks. We also have plastic stirrers which are easy to clean even if the resin cured onto the stick, it can usually be removed by bending the stick slightly.

However, if you are mixing large quantities you may need to use a paddle mixer that will attach to a drill to make light work of the mixing.

Also, if mixing powders into your resin, it is best to use a mixing paddle blade which is usually a flat blade with the corner bent in different directions with a drill shaft welded in the centre, this chops

through the powder as it mixes reducing any clumps of powder so that your mix is free of lumps.

The type of containers that you mix in is very important whether the mix is small or large


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Never mix into anything made from polystyrene type materials such as Styrofoam cups for example as the resin will just eat straight through it within seconds. Also, acrylic type containers are not really suitable. Some plastics containers however are great as even cured resins will release from them such as the above pictured PVC type buckets. We have the standard round buckets or the handy roller buckets pictured above right which have a ‘U’ shaped base allowing you to get every bit of resin out when using a roller for resin application. 

If you are stuck for a mixing container right there and then, as I have been on a few occasions working at home, and you wanted to use a household container then containers such as old yoghurt pots, pot noodle containers or Tupperware will work but make sure these are absolutely clean and dry.  If you are unsure, then test your container with a small amount of resin and leave for 30mins and check for any reaction.

 DO NOT use glass containers as resins can get very hot and cause the glass to break.

All these items can be found here https://www.ecfibreglasssupplies.co.uk/mixing-and-dispensing and buckets here https://www.ecfibreglasssupplies.co.uk/buckets


A picture containing table, bottle, indoorDescription automatically generatedFinishing

After trimming any Grp parts, you will almost certainly need to sand the edges as the cutters you use will leave a sharp corner. For sanding we would recommend the RED Oxide type sandpapers as these are harder wearing than standard sandpaper. Standard off the shelf sandpaper that is normally used for wood or decorating will not have a chance against the abrasive glass fibres. A good quality file and rasp set will also be useful for those areas that are a bit rough and need a heavy filing especially on those thick flash lines left behind from poorly fitted old split moulds.

Once your trim edges have been taken care of you may need to give the GRP gelcoat surface a rub down and a polish especially if the mould or part has been slightly scratched or is dull. To remove any swirl marks or light scratches you can rub down with wet and dry paper moving up the grades for example 800 grit then 1200 grit etc. for flat areas use a sanding block or pad to prevent creating an uneven surface.

Once you have a good smooth surface you can move onto polishing compounds again starting with the course cut and moving up to the finishing cuts and even a UV wax if required?

Abrasives can be found here https://www.ecfibreglasssupplies.co.uk/abrasives

polishes here https://www.ecfibreglasssupplies.co.uk/grp-polishing

and files here https://www.ecfibreglasssupplies.co.uk/6-piece-file-set





Personal protection


Throughout the whole process of GRP Manufacture you will need to wear some sort of personal protection. When handling, decanting or mixing chemicals you should be protecting your skin, eyes, and respiratory system.  Always obtain a safety data sheet (MSDS) for the materials you are using and consult section 8 of the MSDS for advice on exposure controls and in particular section 8.2 for personal protection recommendations.

Eyes: Wear a good quality pair of safety goggles with protection that also encloses the eyes from risk of splashes entering from the top bottom and sides of the lenses, ideally use a cupped type of goggle that encloses the eyes with an elastic strap that pulls the googles tight against the face.

Skin: As fabrics such as standard boilers suits can be absorbent it is best to wear a plastic-coated paper suit that is non-absorbent.  For small mixes with less risk of splashes you could wear a plastic apron but do not get the chemicals onto your fabric clothing as this will hold the chemical against your skin and cause burns or rashes depending on the chemical.  Next will be gloves for small mixes such as a tiny bit of gelcoat or filler for repairing you can get away with a latex or nitrile disposable glove. However, for larger mixes or when laying up we would recommend a good thick pair of chemical resistant rubber gloves.

Respiratory system: when working in enclosed spaces or workshops without adequate ventilation you will need to wear a mask to protect you from vapours such as styrene etc. in some cases where ventilation is good such as outdoors or where styrene levels are continuously monitored to keep them at a safe level you can usually work quite comfortably and safely without a mask. However, remember that styrene is heavier than air and will always lie low so even if styrene readings are low but you are working on a project that involves climbing into a mould or leaning your face into the mould, then we would advise to wear a vapour mask or in extreme cases such as lining out enclosed tanks you will need to wear a air fed mask, these are enclosed helmet type masks  that have their  own ventilation system. Always check with your supplier to ensure the correct filters are supplied with your mask for which ever chemicals you are using


Example of a safety data sheet (MSDS)

When trimming and fibreglass it is also important again to protect your skin, eyes, and respiratory system but this time think about your ears also as the noise from cutting especially air fed diamond tipped wheel cutters can be deafening not to mention the dust that they can create. A good quality pair of air defenders are a must for this part of the process.

The hazards to eyes, skin and respiratory system are different during the finishing process tp that of the chemical handling.  Skin can be irritated due to the dust and minute fibres created by sanding and trimming, eyes can be at risk due to flying debris and dust, and respiratory system can be at risk again due to dust and small fibres.

A picture containing clothing, standing, trouserDescription automatically generatedSkin: The parts when de-moulded can be very sharp around the edges sometimes having ragged edges like sharp teeth and you could be at risk of severe cuts if not adequately protected. Wear thick clothing and maybe invest in some cut resistant arm and hand protection for when carrying demoulded parts. 

When cutting again wear cut resistant gloves and also a boiler suit fitted with a hood which will prevent dust and fibres making there way into your clothing and onto your skin. The ankles and wrists od the boiler suit should be elasticated again for a tight fitting to stop dust and fibres entering your sleeves and having contact with your skin. the plastic-coated hooded suits are ideal for this part of the process as the majority of the dust will fall off or can be easily blown off with a light powered air tool.

Tip:  use barrier cream on your skin before trimming this will stop tiny fibres and dust entering your skins pores and causing irritation.  If you are still experiencing skin irritation from fibres do not take a hot shower as this will open the pores of you skin and will make the irritation, worse take a cold shower first to remove the vast majority of dust from your skin.

Eyes: The safety glasses or goggles that you wear should be of good quality and impact resistant ideally again choose safety glasses with side protection as debris will be flying at all angles whilst cutting.

Respiratory system:  wear a good quality dust mask and ensure that the mask cups and seals all around the mouth and that the metal strip across the nose bends and nips comfortably onto the nose. Do not settle for cheap decorators’ masks especially those that do not seal properly. Always seek professional advice from your supplier.

Extra precautions: it is a good idea to have an eye station as well as a first aid kit available wherever these operations are being carried out as well as adequate signage promoting good safe practices especially within workshops and factories.





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Also keep a good tidy working environment free of obstructions, tripping hazards, spillages, and build-up of dust.

The advice within this section is just standard practice and mainly covers the usual types of PPE required. It does not cover all aspects of health and safety. It is your personal responsibility or whoever is the responsible person as part of a company to ensure that all aspects of health and safety set by Law are adhered to.   We recommend seeking further help from a health and safety advisor especially if you are a company owner and employing staff.

PPE can be found on our website here  https://www.ecfibreglasssupplies.co.uk/personal-protection-ppe

Data sheets can be found on our website by clicking on the product you require and opening the data sheets tab next to item description.