Fiberglass procedures...

Fiberglassing over plywood and one-off fiberglass methods. See: "Boatbuilding Methods", in the left-hand column of the Home page.

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Andy Garrett
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Fiberglass procedures...

Post by Andy Garrett » Sun Apr 08, 2012 10:16 pm

So..., I've looked high and low--can't find my fiberglassing book. Thus, I have a couple of questions.

Using the Glen-L Poxy Shield system, how long do I wait between coats to insure adhesion without the need to sand?

How many coats should I go for before I do my first sand out?

It is my hope that I can get the bottom, full sides, transom and transom edge 'build-up' completely done in a single push. I want to sand after a full cure at that point and add a another coat or two before paint to ensure a smooth finish.

Do I require primer for such a substrate if using Brightside?

Any help is welcome. Thanks.
Andy Garrett

Perhaps the slowest Zip build in Glen-L history...

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Andy Garrett
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Re: Fiberglass procedures...

Post by Andy Garrett » Sun Apr 08, 2012 10:17 pm

BTW, I am using the dry technique with no encapsulation ahead of glassing.
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DaveLott
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Re: Fiberglass procedures...

Post by DaveLott » Mon Apr 09, 2012 4:30 am

Andy - For the fiberglass build up, I would not wait more than one day between coats. A lot depends on the temperature in your shop. The warmer it is the faster the set. My rule is if I can press on it without leaving an inprint it is set enough for the next coat. If it set enough that it feels like it has a soap film then I have to clean and sand.

I have 2 coats in a day followed with a 3rd and 4th coat the following day with only about 8 hours between coats but it was over 80 degrees in the shop.

And then I have had coats that took days to set when the shop was in the 40's
Dave

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Roberta
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Re: Fiberglass procedures...

Post by Roberta » Mon Apr 09, 2012 5:16 am

I agree with Dave. I used a very slow setting hardener and went about 12 hrs between coats. Any longer than 24 hrs, I would let the epoxy fully cure and then sand. Use thin coats once you fill the weave in the cloth.

I do recommend giving the hull a seal coat of epoxy prior to laying down the cloth to prevent dry spots while filling the weave. I allowed the resin to get nearly cured so it was just a little tacky. This really helped to lay out the cloth and kept it in place. One of the things you really need to prevent is having the cloth pull or creep when filling the weave during the first fill coat on the newly laid cloth. Overworking the cloth and moving it around during the intitial fill will cause it to float and you may wind up with voids under the cloth that will be impossible to fill later because the cloth will be scabbed over with resin. You want to prevent the cloth from either bunching up or being stretched duringthe initial fill. Bunching will need to be pulled out to smooth it down. Stretched fabric during the initial fill will creep back and possibly loosen the bond.

I used a 16" window squeegee to float the resin over the cloth. I used only the weight of the squeegee to force the resin into the cloth. Work from the wet edges out, not from dry edges into the wetted part. Start in the middle and work your way outward to the edges to smooth the cloth down and don't overwork it. Trim the cloth with a razor blade while it is in the Green State, or getting stiff, but still pliable.

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Re: Fiberglass procedures...

Post by cusoak » Mon Apr 09, 2012 5:39 am

It should tell you on the teck. sheet how long to wait be for recoat. On the west system that I used the test for recoating was to take your finger nail and try to indent the epoxy if you could still do that then no need for sanding. At 50 drgrees this was about 12 hours at the most. I put on a coat at 9am then another on at 7 or so then the next day get up early ang ck with finger nail. And then 2 more coats. I agree with Reberta on the epoxy first. It make it a lot easiery to hold the fiberglass in place while wetting it out.
Jeff

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Andy Garrett
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Re: Fiberglass procedures...

Post by Andy Garrett » Tue Apr 10, 2012 12:30 am

Very helpful..., thanks gang!

In an effort to reduce waste: How much is a good amount to mix up for each coat on the Zip? (Poxy Shield)
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Re: Fiberglass procedures...

Post by DaveLott » Tue Apr 10, 2012 3:44 am

Andy - I used the West pumps with the Glen-L epoxy. I never could seem to get good quantity control without going to pumps. :(

With the pumps I can mix as little as dab or up to a quart at time. However, I did not like to mix more than a pint at a time because of the time involved for the pumps to work properly. I actually had one batch set up on me while I was pumping. I believe I saw the gent on the fiberglassing DVD mix what appeared to be about a quart at a time. His batches were not small but he also knew what he was doing with much experience


Oh, if you use the pumps be sure to check the calibrations. I found that the hardener (smaller volume) was slightly short on volume. I would have to make 6 pumps of the 1 part to be in proper proportion to the 5 pumps of the 5 part
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Roberta
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Re: Fiberglass procedures...

Post by Roberta » Tue Apr 10, 2012 4:40 am

For the Zip bottom, doing half at a time, I would start with about 8-10 oz. If you run out, you can mix more based on how far the first batch gets you. Better to need to mix more than have a large batch fire up on you before you get it all on. I mixed 9 oz batches because my paper measuring cups held that much with room to mix. My ratio with the System Three General Purpose resin was 2-1 and I used the slowest hardener they offered. If you feel the resin warming up, finish what is already down and discard any that you haven't poured on the boat.

Roberta :D :D
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Re: Fiberglass procedures...

Post by cusoak » Tue Apr 10, 2012 5:24 am

Put your resin in something that is big. Paint tray. That way it is not confined so the heat it creates is spread out. That way the work time is longer.
If you can get someone to help you it is alot easery, one can apply and one can mix.
Jeff

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Re: Fiberglass procedures...

Post by jeffh » Tue Apr 10, 2012 8:27 am

Andy, I did not see a reply to your question about using a primer. I painted the hull, of my first build (16.5 ft. Kayak) with Brightside and used the recommended primer. I think it turned out pretty well. The primer is a bit chalky and quite susceptible to humidity. So now is a good time to use it. Wear a respiratot. It has really strong fumes.
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Andy Garrett
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Re: Fiberglass procedures...

Post by Andy Garrett » Wed Apr 11, 2012 12:59 am

Thanks again me brethren! I think I have my head around now, and I will take Roberta's advise and do a seal coat first. After that, I'll go do some trailer work in the yard for several hours before laying out the pre-sized glass sheets.

Saturday is the day!
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tsmitherman
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Re: Fiberglass procedures...

Post by tsmitherman » Wed Apr 11, 2012 7:19 am

Andy,
When I've glassed by myself or with an inexperience helper, I measured out several small batches of resin and matching batches of hardner, and put them in pairs on the workbench. This eliminated the time to measure out each batch once the process starts, and eliminates the chance of an error in measuring due to the pressure of wanting to get it all wetted out quickly. It is also much easier to teach someone to mix a pre-measured batch than to measure it.

I always use thin coats, and recoat as soon as the previous coat feels stable enough to hold another coat. In hot weather (and depending on the speed of hardner) this may be only a 2 or 3 hours.
Tom
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brad1516
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Re: Fiberglass procedures...

Post by brad1516 » Thu Nov 20, 2014 7:13 pm

did you do your btm fiberglass separate from sides and complete it fully before being the sides ?

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Re: Fiberglass procedures...

Post by gdcarpenter » Fri Nov 21, 2014 8:11 am

When I fiberglassed the bottom I did half at a time. I had disposable plastic cups at the ready with premeasured amounts of resin and a large syringe preloaded with hardener, this way I could mix up the next batch in a jiffy. I then poured the mix into a paint tray with a disposable liner.
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Re: Fiberglass procedures...

Post by bobinpowayca » Tue Mar 17, 2015 3:21 pm

I'm a few weeks off from completing the hull of my Geronimo. I figure one or two encapsulating coats, then a few coats over the glass. I don't think I can plan to put successive coats on within a time frame, e.g., 12 hours or when a fingernail dents it etc., it may be a few days or more between coats depending on when I have time.
So I'm wondering if anyone's used an epoxy system where you don't have to worry about sanding off an amine blush, or solvent washing. I think the Silver Tip system advertises a "no amine blush" epoxy. Any thoughts? Thanks, Bob
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