My first gel coat experience, what went wrong? - SailNet Community

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Go Back   SailNet Community > General Interest Forums > Gear & Maintenance
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Old 05-08-2009
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My first gel coat experience, what went wrong?

Hi All...

Today I undertook repairing large gel coat chips that are under the window frame. I figured it was a good start, since when I put the window back the frame will cover the work anyhow.

I bought a can of Evercoat Gel Kote in white, which came in a 16 fl oz can and with a tube or hardener. The instructions said to add 12 drops of hardener to every ounce of gel.

I poured 3 ounces of gel into a plastic measuring cup. I then pierced the top of the hardener squeeze tube using a drill bit and counted out 36 drops. I used a plastic mixing stick to mix it, which I did for well over the 3 minutes the instructions said.

It didn't get thick. Well, maybe a bit thicker than milk. The place where I needed to apply it was vertical. So I used the mixing stick to dab some on the chipped areas and spread it with a plastic putty knife. It held on, I assume by capillary action.

As I was finishing it did start to thicken, but quickly turned to cottage cheese and was useless. I expected that, as the pot time is only 15 minutes or so.

The temp was about 70 deg F, so I doubt that was the problem.

I assume it is cured by now, but I left before the two hour cure time expired. I'll check it out tomorrow to see how it did, but I expect to see thin spots that will need to be sanded and recoated.

Is gel coat supposed to be so thin?

Also, the 12 drop measurement seems pretty subjective. Wouldn't the amount in each drop depend upon how big the hole is, how hard I squeeze and so on? From what I had read, the ratio of headener to gel is critical.

Thanks...
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Old 05-08-2009
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the drops are not very dependant on the hole size.

they call no sag but its not, if you really want you can add some silica to thicken it some. you will then need to add a layer of non thickened over it.

also if you need more time there is 2 things you can do, one use 10 drops per oz, or after mixing pour it out on to a plate, this will buy you another min or 3 ( well the plate part will ). once it starts setting you are done there is nothing you can do, it does become useless. also 3 mins of mixing is over kill, a good solid min should be okay, as long as its through
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Old 05-08-2009
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So the thinness was normal? How do people gel coat things that are vertical or tilted? I could thicken it as you said, but it seems that this just kicks the problem down to road to the next layer.
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yes it was normal. and yes it does pass it down to the next layer, but the best way for the final coats is to use a roller. you can then wet sand out the roller marks.

vertical surfaces are done with many coats
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Quote:
Originally Posted by scottyt View Post
yes it was normal. and yes it does pass it down to the next layer, but the best way for the final coats is to use a roller. you can then wet sand out the roller marks.

vertical surfaces are done with many coats
Okay, thanks. Well in that case I guess, all things considered, it didn't go too badly. Tomorrow I'll do another coat with a roller.

How much silica is advised ?

Any special roller requirements? I assume one with very short nap?

How fine a sand paper should be used between coats?
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Old 05-08-2009
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Gel coat paste

I've never used any of the Evercoat products (and gererally distrust any product that uses a K where it ought to have a C) but I think if you are trying to repair chips in gelcoat that what you need is something more like a gelcoat repair paste that liquid gelcoat.

I've used the gelcoat repair kits from Spectrum Color on my Whaler with some success. Their claim to fame is pre-matched color for a bunch of different production boats. The repair kits have a 2 oz jar of gelcoat thickened into a paste which does a nice job of filling chips where you have some depth.

Gelcoat needs to be protected from air in order to harden correctly and the standard approach is to either add a special 'wax' to the liquid gelcoat or to spray PVA stuff over it... but these kits come with all the right stuff premixed.

Another option is to use white Marine-Tex. Trowel it into the chip and then tape some plastic wrap tightly over it while it hardens. But you may find your boat is not the same white as the Marine-Tex - or even the evercoat gelcoat you are using now. Not all white boats are really white...

Actually, the plastic wrap trick will work with the gelcoat paste also.

What I do is mask off the repair with some very thin tape, fill the chip or gouge and then tape the plastic wrap over the repair and use my finger to try and smooth it out. The plastic wrap gives the repair a smoother finish.

You will end up with a little extra thickness (of the tape you used to mask) and if you are trying to go for perfection you can wet sand with 600, 1200 and then buff and wax to make it even and shiny.

Even if you don't use Spectrum's products, you might have a look at some of their instruction pages

Last edited by TaylorC; 05-08-2009 at 08:39 PM.
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Old 05-08-2009
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Thanks Taylor, there was some reason I was advised not to use paste, but a the moment it escapes me. This gel coat had the wax in it, so I didn't need to spray the PVA on it.

No one has a color match for my beige Scampi deck. I was thinking of going to Home Depot to get some paint color chips, find a close match, then ask them what the color formula is. Maybe then I can replicate it.

My boat has gel coat chips and dings and screw holes all over it, so this was my first step in learning to fill them.
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As I recall, Evercoat also makes some color matching stuff, a dab of red and a dab of black might give you a biege shade. Do the mixing ahead of time, before you add the catalyst.

My Whaler 'desert tan' color match was very good, but even if it is supposed to match, the amount of UV a boat gets in one place vs another make it more an art than a science. Certainly no one makes a color match for my sailboat... its not part of any production run.

If you can get a paint chip to match your boat and then walk up and down the dock until you find a major brand boat that is the same color, that might give you a way to order a close match premixed.

Also - if you want to see my gelcoat trials, check out the fun we had with my Whaler

Last edited by TaylorC; 05-11-2009 at 03:38 PM.
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Old 05-08-2009
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jarcher - thanks for sharing your experiences. I'm planning on trying similar repairs for the first time this season and it's pretty intimidating I guess what you've discovered is what all the stories mean when they say "it's messy".

Btw, on the suggestion of walking down the dock to find a color match: you're almost guaranteed to pick a bad match, since the lighting conditions will surely be different (based on angle, shadows, glossiness, other stuff in your visual field, etc.). The eye is notoriously susceptible to color trickery.
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Its messy, I still have it on my hands and my new jeans. If it does not wash out I'll have a pair or boat jeans

I have to revisit why I didn't use paste. I know there was some reason.

Tomorrow, I'll sand it lightly and apply another coat with a roller. I'll post an update then.
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