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#1
03-03-2013, 11:59 AM
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epoxy
Okay As you know I am doing my transom with epoxy.. I need to know what the recoat window is for epoxy...I have heard one week to 36 hours of coarse depends on temp and humidity. lets say 75 + 40% humidity or what ever it is in panama city at the time... my foam should be here next week for a nice weekend project.. My epoxy is in .. and all the glass.. the temp according to the forcast calls for 70+ temps and sunny.
This will be the first time I bag with epoxy.. I dont want to make a very costly mistake.. So any suggestions would be great.. 
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#2
03-04-2013, 09:25 AM
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Recoat time will be dependent on the hardener used. Generally, you can tell if it is still wet by seeing if you can dent it with your fingernail. At 70 degrees with a normal curing hardener, it will likely be fully cured before 24 hours or near fully cured. If I am close on the time, I will generally wait until it dries fully and then scuff the surface with 100 grit or rougher sandpaper and coat over that.
The biggest mistake you can make with epoxy is not getting the ratio correct and also mixing too big of a batch. If you mix a large batch don't stir too long and immediately pour it into a large container so the resin is sitting shallow. If the mixed resin is sitting in a container more than say 3/4 inch deep it will start to exotherm/heat up really fast!
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#4
03-04-2013, 10:35 PM
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If you can but sometimes it is not possible to wash it off due to location. West Systems says wash with Scotch Brite and plenty of water or abrade. It will bond great if you sand and wipe dust off with Acetone IMO. I buy blush resistant Epoxy now but I always sand anyhow.
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#5
03-09-2013, 10:21 AM
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Many years ago W.E.S.T. Systems published an article on cleaning/prepping epoxy. They tested all kinds of different solvents for prepping between layers of glass. The results were surprising, plain water was the best in every test. So we did our own testing and found the same result. Turns out most solvents (especially acetone) are not very clean. They offered a way of testing the solvent - get a perfectly clean rag, saturate it with the solvent of choice and then wipe it on a mirror. If it's clean there will be nothing. If it's dirty it will leave streaks. Quite an eye opener.
In our tests with epoxy, the absolute best was to wet sand (60 or 80 grit) and let dry naturally.
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#6
03-09-2013, 01:28 PM
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I noticed in the FGCI catalog they say "DO NOT wipe with acetone". So I asked what is best, they told me rubbing alcohol, the 91% stuff is good. I always sand with 60 grit wipe twice with alcohol. My 2 cents.
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#7
03-09-2013, 02:56 PM
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When I do an epoxy layup where I expect to add something later that's going to make a secondary bond, I wet in a layer of peel ply over the last layer of glass. The amine blush peels off with the peel ply, and it leaves a surface that's ready for a secondary bond with no sanding. To me, the time savings is well worth the minimal cost of the peel ply.
Dave
__________________
Blue Heron Boat Works Reinventing the wheel, one spoke at a time.
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#9
03-21-2013, 10:30 PM
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Quote:
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#10
04-18-2013, 06:30 AM
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Okay i have a gouge on the bottom of the hull about 10 long.. I wanto repair with epoxyand glass.it is anout .1/16 inch deep by about an 1/8 wide... Should i just feather out and mix cab and epoxy to a paste oe should i feather way out and put some glass on... I dont have good results with glassing upside down. How do i keep the resin to stay in placewith out running all down the hull to keel... Cabosil resin and milled glass work instead of resin and glass..i think it is more less cosmetic.. I plan onpriming with 545 and bottom painting..
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