Estimating how much epoxy is required to wet out fabric is based on the fabric weight and square footage. The table below provides estimates of the amount of epoxy needed to apply 1 sq. ft. of fiberglass cloth followed by two fill coats.
|Fabric Product Number||Fabric Weight Per Yard*||Mixed Epoxy Needed|
|740 Glass Fabric||4 oz||1.4 fl. oz.|
|742 Glass Fabric||6 oz||1.61 fl. oz.|
|729, 731, 732, 733 Glass Tapes||9 oz||1.94 fl. oz.|
|745 Glass Fabric||10 oz||2.05 fl. oz.|
|727, 737 Biaxial Fabric||17 oz||2.81 fl. oz.|
|738 Biaxial Fabric with Mat||23.8 oz||3.55 fl. oz.|
*Includes 15% waste factor. More (or less) may be needed depending on the job and personal application technique. The epoxy is applied at room temperature, approximately 72° F.
Estimating Epoxy Amounts
This formula will help you when estimating the amount of mixed epoxy needed to wet out fiberglass cloth (assuming a resin-to-fiber ratio of 50:50) and apply three rolled epoxy coats to fill the weave of the cloth, i.e. “fill coats.” The formula includes a waste factor of approximately 15%; however, more (or less) may be needed depending on the job and personal application technique. The epoxy is applied at standard room temperature, approximately 72° F.
Gallons of mixed epoxy=A× [(Wf×0.00085)+0.0075]
A=Total area covered by fiberglass. Units are in square feet (ft2)
Wf =Total weight (W) per square yard of fiberglass (f) cloth used in laminate. Units are in ounces per square yard (oz/yd2), i.e. 6 oz fiberglass cloth weighs 6 oz/yd2.
Let’s use the Optimist pram as an example:
|Bow: 322 in2||Transom : 507 in2||Side×2:3784 in2||Bottom:3444 in2||Total sq in: 8057 in2|
|÷ 144||Total outside sq ft:||56 ft2|
- The INSIDE is covered with 6 oz fabric and three fill coats. The bow box is covered with 6 oz fabric on one side only.
|Bow: 322 in2||Bow box: 720 in2||Transom:507 in2||Side×2:3784 in2||Bottom:3444 in2|
|Total sq in: 8777 in2||÷ 144||Total inside sq ft:||61 ft2|
- Outside calculation 56 ft2 [(12 oz/yd2 × 0.00085) + 0.0075] = 0.99 gal
- Inside calculation61 ft2 [(6 oz/yd2 × 0.00085) + 0.0075] = 0.77 gal
Total 1.76 gal mixed epoxy