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Estimating Quantities

Based upon Medium reactivity catalyst Butanox M50.

Please consult the Technical data sheet for your particular Resin before use, the above chart is merely a general guide to cover most general purpose resins.

Do’s and Don’ts

1. Measure catalyst accurately and stir thoroughly into Resin, wearing appropriate PPE.
2. A Catalyst dispenser is ideally required for accurate measuring.
3. The cure of the resin will begin as soon as the catalyst is added, and the speed of the reaction will depend upon the particular resin and activity of the catalyst.
4. Do not mix more resin than you can practically use, work in smaller more manageable amounts if necessary. Unused resin in volume will cure and an exothermic reaction will occur. If you have any volume of resin left over move to a safe spot outdoors and fill container with cold water. This reaction is exothermic and the temperature can rise to over 150 degrees Celsius in an unfilled casting, in the laminate it will be considerably less.
5. Once the resin starts turning to a jelly like consistency, you must immediately stop laminating and clean your tools, finishing off your immediate area.
6. Always use 2% catalyst in Gelcoats.
7. If adding pigment do so first and thoroughly stir in mixing well before adding catalyst, be careful not to under or over pigment.

Guidelines for estimating Resin to Fibreglass ratios – These are approximations and for guideline use only, variations/complexity of laminate/mould surface may alter quantities slightly.

   Material                                             Resin

300g (1oz) CSM                               650g Resin per sq mt
450g (1 ½ oz) CSM                          1kg  Resin per sq mt
600g (2oz) CSM                               1.4kg Resin per sq mt
900g (1oz) CSM                               2 kg Resin per sq mt
125g Plain weave Glass cloth          150g Resin per sq mt
200g Plain weave Glass cloth          250g Resin per sq mt
300g Woven Roving                         300g Resin per sq mt
600g Woven Roving                         600g Resin per sq mt
800g Woven Roving                         800g Resin per sq mt
600/300 Combination Matt           1.2 kg Resin per sq mt
800/450 Combination Matt           1.7 Kg Resin per sq mt
450g Biaxial Glassfibre                 500g Resin per sq mt
600g Biaxial Glassfibre                 700g Resin per sq mt
800g Biaxial Glassfibre                 900g Resin per sq mt

200g Carbon Fibre                        300g Resin per sq mt
375g Carbon Fibre                        550g Resin per sq mt
650g Carbon Fibre                        950g Resin per sq mt
180g Kevlar/Aramid                      270g resin per sq mt
300g Kevlar/Aramid                  450g resin per sq mt

Calculating quantities

To estimate the quantities of materials for your particular project you will need to know the surface area in square metres.

For example, you want to make a part 7mm thick out of Fibreglass and have a Gelcoat finish and your mould is 3 sq mt in total.

Gelcoat is applied 600g per sq mt, so 3 x 600g = 1.8 Kg of Gelcoat is required.

Chopped strand matting: Each layer of 600g is approx 1mm thick so you would need 6 layers.
6 layers x .600g matt = 3.6 kg per sq mt x 3mt (mould area) = 10.8 Kg of 600g matt is required.

Resin is calculated between 2 – 2.5: 1 Resin to Glass ratio. So, you have 10.8 kg of fibreglass matting, 10.8 x 2 = 21.6 kg of Resin minimum, say 25kg of resin to be safe.

If the Gelcoat that is applied at just over 0.5mm and 6 layers of Glass each 1mm, your laminate should be approximately 6 -7 mm thick. This varies upon operator, some experienced laminators are very good at keeping the resin:glass ratio down to the minimum, whilst others new to laminating will use more resin, this will effect the weight of the panel and can cause varying degrees in laminate thickness.
Good consolidation of the laminate is key, use a paddle/washer or any other type of consolidating roller between each layer, draw the resin through and apply more resin only if there are any dry patches, repeat this throughout lamination for best results.

This advice and information is given in good faith for guidance only. and is given without warranty, users should determine information given and using their own judgment to determine suitability.