Star 45

Star 45

Tuesday, September 09, 2008

fiberglass notes

From: "John F. Howard"
Date: Tue, 1 Aug 2006 08:18:55 -0500
Subject: RE: [Star45] Re: Glues and adhesives, wooden boats, fiberglass-wood

2. Heating epoxy – Heating the epoxy or surface will cause the epoxy to thin out a bit to help soak into the wood and joints. It will also shorten the pot life (working time). Strip Canoe/Kayak builders recommend applying the first coat of epoxy late in the day as the hull is cooling to help prevent air bubbles. Second or more coats are added to the first in the green stage or well sanded if applied later. Final finish on the canoes is varnish to protect the epoxy from UV rays. On my model airplane fuselages, I used a very slow (2 hour) resin, thinned, to apply the .5 oz cloth and did not heat it, came out nice.

4. Epoxy Cure Rates – Pick up a West Systems User Manual (or look at it online). West hardeners pot life times (at 72 degrees) are; 205 – 9-12 min, 206 – 20-25 min, 207 – 22-27 min, 209 – 40-50 min. Ambient temperature will affect these times, higher temp faster set up (shorter pot life). To extend the pot life a little, after mixing the resin in a cup, pour the resin into a flat container (pie pan). Keeping the resin in the cup as a thick mass will generate more heat and set up faster; the pie pan allows the heat to escape and extends your time. Thinning the epoxy will not extend your time, only allow it to flow and penetrate better.