mold lay-up problems need help

bbh57 · #1 02-23-2007, 12:01 PM

I've made a mold for the rear cap on my boat. I thought if I used gelcoat first in the mold I would have a finish without pinholes that would be eaiser to fair before paint. I put a few coats of gelcoat on and allowed it to dry then glassed a layer of 3-4 oz mat. when it kicked it melted the gelcoat and made bubbles everywere. what did I do wrong

Briguy · #2 02-23-2007, 02:01 PM

Perhaps call these people.

Fiberglass Services
(941) 923-8112

fiberglassservices.com

5612 Lawton Dr # C
Sarasota, FL 34233

Ryank · #3 02-23-2007, 03:34 PM

I could be wrong but don't you lay up the glass and resin etc, after it has been removed from the mold and sanded etc then the gelcoat gets sprayed on?

1bayouboy · #4 02-23-2007, 06:04 PM

Typically the gelcoat is spayed in the mold using the kind that doesn't have wax (it won't cure if exposed to air), then the glass and resin is laid in while the gelcoat is still tacky.

Bigshrimpin · #5 02-23-2007, 06:32 PM

Never heard of that . . . When you say melted . . . what do you mean? It got really HOT and melted?

hermco · #6 02-23-2007, 07:08 PM

Probably what is called alligators, when the gel is not properly catalyzed or mixed and not cured in areas when you put on your check mat. The gel will "crinkle",bubble, and look like alligator skin. Just finish your laminate and then grind out and putty the gators on the part after you pull it from the mold.

bbh57 · #7 02-23-2007, 07:34 PM

thats what happened I tried it twice, gel was non wax, I waxed the mold and made sure I kicked it to 1.25 perct.

hermco · #8 02-23-2007, 08:27 PM

There are a plethora of factors that can cause the gators to appear. They can appear more often after they win the national championship etc.........
Seriously, they can be caused by bad,not agitated gel,cold temp,improper mixing,not waiting for the gel to cure,etc. Also make sure the mat layer is catalyzed "hot" as this will decrease the possibility of the gators appearing.
It also helps if you beat them for the championship, then they won't appear till next year!

strick · #9 02-23-2007, 10:58 PM

Thats kind of what I was thinking too that it did not fully cure all the way. I've never used Gel coat except for spot repairs so I was afraid to respond to you post.

Hermco- are you supposed to let the gel cure totally before you start laying up the matt? or start laying up while it is tacky? I like duratec sanding primer and I usually start laying up matt over it while it is still a little tacky.

strick

bbh57 · #10 02-23-2007, 11:47 PM

The first time I tried it the gel was tacky. the second time I left it 24 hrs. same results both times.the only thing I didnt do was kick the mat a little hotter. I think I'll take Hermco's advice and continue the lay-up and do the repair. thanks for the feedback everyone.