Estimating Coverage & Material Requirments

1. Different amounts of resin are required to wet out different forms of Fiberglass.

    For example, one gallon of resin will wet out approximately the following amounts of Fibreglass:

                          40 square feet of 8 to 10 oz. cloth

                          50 square feet of ¾ ox mat

                          30 square feet of 1 ½ oz. mat

                          35 square feet of 24 oz. roving

 2. In the event successive layers of glass are laid up before previous layers gelled, coverage

     will be greater.

                          The desired thickness for a Gelcoat is generally 15 mils (0.15”).

                          The equivalent to 25 square feet per quart or 100 square feet per gallon.

     For example, suppose a boat is to be fabricated having a hull surface of 100 square

                           feet using Gelcoat, ¾ oz. mat and 2 layers of 1 ½ oz. mat.

                           Based upon the rules stated in #1 and #2, the following is required.

                           From #2, 1 gallon of Gelcoat is required. 

                            From #1 resin needed is:

                                          (100 sq. ft. 3/4oz mat) / 50=2 gallons of resin

                                          (200 sq. ft. 1 1/2oz mat) / 30=6.6 gallons of resin

                                                                                Total 8.6 gall9ons of resin

3. The percentage of glass to resin in various laminates is:


Type of fibreglass

% Glass

% Resin

Chopped Glass lay-up



Mat Lay-up



Woven Roving Lay-up



Cloth Laminate




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