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New to Fibre glass? Example for beginners – Job 1
7th March 2018 TFarrugia

New to Fibre glass? Example for beginners – Job 1

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If you have never made anything out of ‘glassfibre’ – you may wish to ‘have a go’ – if you do, please read through, we will start by making a small sheet of ‘Glassfibre’ – to get a ‘feel’ for the material – it really is not difficult! All setting times are based on a working temperature of about 15 C.

We should also add, if you don’t have time to work through this all, there are some very helpful note’s at the bottom of this blog!


You will need:

  1. A sheet of ‘Formica’ roughly 1 Metre x 1 Metre – it does not have to be exactly this – it is a working surface, and may be a bit smaller.
  2. About 1 Litre (or 1 Kilogram) of Polyester Laminating Resin with no less than 10 c.c. (= 10 millilitres or 10 m.l.) Catalyst (polyester resin ‘hardener’).
  3. About 1 square metre of glass reinforcement – this really should be ‘Chopped Strand Mat (‘C.S.M.’) of ‘weight’ 450g per square metre – sometimes called 1 ½ ounce chopped strand mat. Do not use anything ‘thicker or heavier’ at this stage – if you can only get 300g./Sq.M. (1 oz.) material, this will be O.K. Do not worry about the binder type used for the mat – it may be ‘Emulsion’ or ‘Powder’ bound – either will do. Find out more about ‘Emulsion’ and ‘Powder’ CSM’s here.
  4. Some means of measuring out the Polyester resin – this should be made from ‘Polythene’ or ‘Polypropylene’ – not ‘Polystyrene’ as this is dissolved by Polyester resin! How to tell the difference – ‘Polythene’ usually has a slight ‘waxy’ feel or is slightly ‘milky’ in transparency, it is also ‘softly flexible’, and is commonly used in ice cream cartons, and domestic kitchen measuring kit. ‘Polypropylene’ appears similar to ‘Polythene’, but has better transparency and better quality ‘feel’. ‘Polystyrene’ is of high clarity and more brittle – it is also used for containers but is often white or coloured; similar plastics used for toy’s, telephone’s, or instrument cases. A cheap ½ Litre kitchen measure may often be made from ‘Polythene’.
  5. Two cheap ‘throw away’ 1” or 2” brushes.
  6. Mixing sticks, a pencil, and a pair of cheap scissors.
  7. Some car polish, or similar product.
  8. A working area – which should be clean, dry, and reasonably warm. This may be outside – weather permitting. If indoors, ensure that it is well ventilated – polyester resin has a pervasive smell, and the fumes are harmful as with many solvent loaded products. It must not contaminate areas used by babies or children – who must be kept away from the materials whilst in the wet state. Use of the kitchen is not recommended.
  9. A container of water – about 1 Litre – for safety in event of eye contamination. Treatment for eye contamination is to irrigate immediately with water, and seek medical attention: with sensible care – you should never need it!
  10. Barrier cream for the hands, and/or gloves.
  11. Resin cleaner for the skin.

Optional additions:

     12) Acetone or Estasol (trade name for an acetone substitute) – about ½ Litre. Acetone is a solvent for ‘unset’ polyester resin, for cleaning tools and surfaces – not for the skin. Unless cleaned with acetone whilst ‘wet’, all tools and surfaces will ‘set’ with catalysed resin.

     13) Consolidating roller – paddle type – an essential tool for any serious glassfibre work. Acetone is essential for cleaning.

     14) Goggles and overalls as deemed necessary. Goggles are essential if there is any likelihood of splashing or messy working. It should be noted that learning a clean and neat working style is essential! Messy working means that the job will be likewise.

Woohoo, I think we should be ready!


Now – how to make your first glassfibre sheet:

Read warning labels and instructions on Resin/Catalyst/ Glassfibre packs.

  1. Thoroughly clean the sheet of ‘Formica’. Wash with detergent and water, and dry thoroughly, or wipe well with acetone and allow to dry. With a pencil, mark out a square in the middle about 30 cm x 30 cm square, (1 foot square).
  2. Thoroughly polish the surface with a wax polish, and lightly buff with a soft cloth. (Note; for reasons of economy, ‘any wax polish’ has been specified – for ‘professional quality’ mouldings, particular ‘GRP’ type formulated release agents should be used.) ‘Formica’ will usually release from ‘glassfibre’ on its own, polishing in this example is for ‘good practice’ and ‘insurance’.
  3. Using scissors, cut two sheets of the glass chopped strand mat into about 30 cm x 30 cm square – about one foot square. Note the fibres will be very ‘loose’ – handle carefully!
  4. Time to mix the resin! This is where it either gets messy or not! Using the measure carefully pour out about 300c.c or about ? Litre of resin from the resin container into the measuring pot.
  5. Addition of the catalyst to the resin starts the setting process. Polyester resin will not set without addition of the catalyst. Usually, polyester layup resin requires 1% (one part of catalyst per hundred parts of resin) addition to set. If the catalyst is a liquid, this will be about 3 drops catalyst for ever 10c.c (10m.l.) of resin. Thus for 300 c.c. of resin, you need 3 x 300/10 drops = 90 drops: or 300 x 1/100 = 3 c.c. catalyst.
  6. Some catalysts come in paste form – see the instructions on the packs, for the amount to add. Add the measured amount of catalyst to the resin and mix very thoroughly, including the sides and base of the container. Be careful!
  7. Using a clean brush, paint the catalysed resin onto the Formica to cover the marked square.
  8. Take one of the pre-cut sheets of glassfibre chopped strand mat, and lay over the wet resin.
    1. If you have a consolidating roller, gently roll the glassfibre into the resin, adding more resin until surface has a ‘satin’ finish, translucent without white patches.
    2. If you do not have a consolidating roller, using the resin brush, stipple with the end of the brush to wet out the glass, adding more resin as required. Do not ‘over work’ the glassfibre, since this process is liable to transfer glassfibres to the brush – use a vertical ‘dabbing’ style – do not ‘brush’.
  9. When first laminate is ‘clear’ – without ‘white’ patches – not before! – gently paint a second layer of resin onto the laminate, – repeat ‘8), and 8.1) or 8.2) above.
  10. You will have some ‘waste’ resin mix in the pot – do not pour onto the laminate – resin rich laminates are bad practice. After about twenty minutes, this resin mix may start to heat, depending upon the amount left in the pot. – this is the ‘exothermic chemical heating’ process common to all thermosetting plastics.

Your laminate should set in about 3 to 4 hours, depending upon the temperature. Do not worry if the surface remains slightly ‘tacky’ – this is caused by moisture in the air. Leave it to ‘cure’ in warm conditions for 24 hours, do not be tempted to remove it before curing! To remove, gently bend the ‘Formica’, and your laminate should spring or peel off.


Note A: A consolidating roller is a very important tool in glassfibre work. Consolidating – removing air from within a laminate – is very much easier with a roller, and what is perhaps more important from a beginner’s viewpoint, it avoids the likelihood of finding that ‘stippling’ with a brush can be messy unless care is used, clean with acetone whilst wet with resin!

Note B: Because very little catalyst is used in polyester glassfibre work, measuring can be a pain! Small measures or syringes may be obtained. It is worth remembering that medicine measuring plastic ‘teaspoons’ contain about 5 c.c. Never use metal spoons with polyester resin catalyst (M.E.K.P.) because it is highly corrosive! Adding too much catalyst will speed the setting time, but is not, in general, good practice; it may weaken the final laminate and will also reduce the ‘pot’ life of the mix.

Note C: ‘Stippling’, or dabbing the laminate with the end of a brush should be carried out with the brush as dry as possible. Care must be used with chopped strand mat, since the fibres become loose when wetted out with resin, and will tend to stick to the brush unless care is taken. The process is totally feasible for small areas, but a consolidating roller is vital for larger areas, where ‘stippling’ becomes impractical.

Note D: Moisture in the air – depending upon humidity and temperature – will contaminate the outer surface of the polyester resin mix, and interfere with the setting process. This produces a surface tackiness, which should not be read as the failure of the laminate to set. It should be noted that water contamination, or freezing will destroy the ability of a polyester resin to set and cure.

Further notes on this phenomenon are included in the Blue Gee ‘Glassfibre and Epoxy Wood Book’.

We LOVE hearing from you so please get in touch and tell us how you got on! we always enjoy viewing peoples work so feel free to send in some pictures – who knows you may see it featured on our site!