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Old 25 August 2015, 18:20   #1
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Gelcoating - Upside down??

Got a couple of gelcoat chips on the chines that I will be sorting some time over next couple of weeks.
My only experience with gelcoat was 30 years ago repairing a bike fairing.
As I remember it, it's the consistency of emulsion paint.

Turning the boat upside down isn't an option.
Question is - How do I get the correct thickness in one go, with gravity working against me?
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Old 25 August 2015, 18:56   #2
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With difficulty!

If you are using gel rather than flow coat you need to exclude air. So get some clear plastic (acetate OHP film is good if anyone still uses such technology!) For a chine you might need to add a crease. Slap on the gelcoat, you can thicken it with some epoxy filler like glass baubles. Use the acetate to hold it in place, secure with masking tape. Remove when hard and sand to shape.

If you are using flow - the wax may float upwards? In which case you may have (non-)sticking issues to the substrate which is above it. Never used flow upside down.

Or use a plastic padding gelcoat filler which is like putty. But harder to colour match.
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Old 25 August 2015, 18:56   #3
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Oh and consistency is more like honey
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Old 26 August 2015, 02:53   #4
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I don't think flowcoat works that way, but happy to be corrected. I think the wax moves to the surface, not the top. I've been using it on various surfaces, some of which are upside down without issues so far.
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Old 26 August 2015, 03:41   #5
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no expert but just made a console for my sib used flow coat up side down no issues plenty of hardener put acetate over it as shiny says to get finish it wont be perfect but better than a chip.
there's also vacuum bagging for gel coat.

look on east coast resin supplies the have videos of all procedures with list of stuff needed good lads to talk to for info and quantities needed

me personally i would go with flow coat you can thicken up with a powder if required finish with a dremel to get rough bits off for small chips
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Old 26 August 2015, 04:02   #6
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Thanks for replies.
Looks like either way would work. (plastic to contain and set gelcoat or thickened flow coat)
I'll give east Coast a call before ordering and see what they say.
If I was shy of existing surface in one go, could the gelcoat be built up in layers?
As you'd expect, the gelcoat is quite thick at the chines.
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Old 26 August 2015, 05:28   #7
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Quote:
Originally Posted by cjj216 View Post
Thanks for replies.
Looks like either way would work. (plastic to contain and set gelcoat or thickened flow coat)
I'll give east Coast a call before ordering and see what they say.
If I was shy of existing surface in one go, could the gelcoat be built up in layers?
As you'd expect, the gelcoat is quite thick at the chines.
not an expert but i would build up past and flat back with different grades of paper and polish but east coast might have a product or a method to help you.

cheers
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Old 26 August 2015, 06:35   #8
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I managed to gelcoat my chine chips from below, using the plastic on top method followed by a little flatting down. No real issues, where I did get the odd run I just wet and dried it off.
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Old 26 August 2015, 07:28   #9
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Depends on the thickness to be filled. Cabosil increases the thickness of gel and makes it run less. Other fillers don't stop gel running or falling off as good as cabosil. Cabosil can be used as a filler itself. It is very strong but sanding will be a pig. You could thicken a bit of gelcoat with it, till it will stand up on its own then lay it on the boat and cover with film. If you wanted it easier to sand add another filler like microballoons. I love mixing my own fillers. It's very satisfying but not always cost effective.

Ecs make their own gelcoat filler. It's good for gap filling but too thick to skim coat and get a pin hole free finish. It would probably be fine on a corner or filling chips up to 10mm but it can pull itself off a surface if you try to fill tiny holes. It's very strong, needs no extra wax but takes a while to go off. At least 24hrs before sanding.

Plastic padding gelcoat filler is really nice to mix up. Goes off in minutes and can be sanded in hours. But it is a funny colour white and quite brittle. Perfect for small chips

Any picture of ur issues
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Old 26 August 2015, 08:52   #10
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Gel coat is thixotropic and doesn't particularly sag, it's used on vertical surfaces when moulding.

Wipe the area clean using detergent, cut back the chipped surface and the area around the chipping using 60 grit abrasive paper. Don't finger the surface. Mask up the good area around the damage. Apply successive coats of gel until it is proud of the surrounding hull. Cut it back using whatever tools you have - file, rasp etc. Level and finish it by going down the grades of abrasive paper. Remove the masking tape and finish with 800 grit wet n dry blending into the original hull. Finally polishing with Tcut or similar will shine it up.

There is no need to add wax to the gel coat to exclude the air since you're removing the surface anyway. The surface will be tacky but it will be cured properly below the tackiness.

Goid luck with it.
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