Fiberglass cure time

wallybygolly · #1 (**permalink**) 02-12-2007

How long do I need to leave for the resin to cure fully before I paint over it and put the boat in the water? The only thing I can get at the boat yard for the next month is 3 days over a weekend...think is going to be a problem?

Figured like this:

Day 1: Cut bad fiberglass out, dewax, lay backing plate, start grinding (maybe)

Day 2: Finish grinding, lay the fiberglass, sand rest of bottom

Day 3: Paint bottom

Day 4: (Monday) drop back in water

Am I leaving enough time for everything to cure/dry? Weather will be in the 80s...sunny...about 50-65% humidity.

Thanks.

sailingdog · #2 (**permalink**) 02-12-2007

It depends... You don't say what brand of resin you're using, or whether you're using the fast curing hardener, the standard hardener or the slow-curing hardener.

Your best bet is to ask the manufacturer for their recommendation on what you are doing...

Also, you're making the assumption that it isn't going to rain...but you don't say where you're located. In many parts of the country, early March is a good time for rain or if you're further north, snow. You've probably just jinxed yourself by saying that it will be dry, hot and sunny... so if it rains all that weekend, don't be too surprised.

wallybygolly · #3 (**permalink**) 02-12-2007

I'm in Hawaii, and down by the coast if it does rain, it will be in the morning for only a few minutes...but yeah, I can pretty much predict what the weather will be like next weekend.

I heard good things about West System...the 105, I think, specifically. So unless, somebody offers a better alternative, that is what I think I'll be doing. I'll be picking up the recommended West System hardner as well.

sailingdog · #4 (**permalink**) 02-12-2007

In that case, I'd go to westsystem.com and see what they say.

wallybygolly · #5 (**permalink**) 02-12-2007

Their website was a great help...they are saying 1-4 days for it to fully cure. What they didn't say was if that could be underwater or not...anybody know? I'm looking through Google as we speak...

k1vsk · #6 (**permalink**) 02-12-2007

most of the West system products have inhibitors to prolong shelf life which works against you in curing time regardless of what it says on the label. The resin will not FULLY cure that fast and even if it does, you'll still need to thoroughly remove the amine blush residue. I'm sure people have done it as quickly as you propose but that timeframe is not the best, particularly below the waterline.

You'd be bettert served to get a good vinylester resin from a reputable mfg and make the extra time to allow proper curing.

SailorMitch · #7 (**permalink**) 02-12-2007

I used MAS epoxy when I barrier coated my boat, and they said to allow 6 days for a full cure. I highly recommend MAS by the way. But whatever product you use, call them to discuss your situation. You don't want to have to do this over again because you rushed it.

sailingdog · #8 (**permalink**) 02-13-2007

You really don't want this repair to fail because you rushed it, since it sounds like you're patching a hole.