This formula will help you estimate
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 72F.
Gallons of mixed epoxy=A x[(Wf x 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 in the previous article as an
: 507 in2
||Side x 2:3784
sq in: 8057 in2
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.
||Side x 2:3784
|Total sq in: 8777 in2
Outside calculation 56 ft2 [(12 oz/yd2 x 0.00085) + 0.0075]
= 0.99 gal
Inside calculation61 ft2 [(6 oz/yd2 x 0.00085) + 0.0075] = 0.77 gal
Total 1.76 gal mixed epoxy
Note: a Group Size B resin and hardener makes 1.2 or 1.3
gal of mixed epoxy depending on hardener.
Epoxyworks 18 / Fall 2001
Copyright 2001, Gougeon Brothers, Inc. All rights reserved.
Last Modified on 10/28/02.
Reproduction in any form, in whole or in part, is expressly forbidden without the consent of the publisher. EPOXYWORKS, Gougeon Brothers, WEST SYSTEM, Episize, Scarffer and Microlight as used throughout this publication, are trademarks of Gougeon Brothers, Inc., Bay City, Michigan, USA.