Fibreglass.

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BernieQ2
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Fibreglass.

Post by BernieQ2 »

Question for those more knowledgeable than me..
This is the cover off the original aircon from the motorhome... It had that hole in it when I bought it... just had tape over the hole.
How is the best way to fix the hole...I have bought a fibreglass repair kit..do I put something under the hole and fibreglass over it...or fibreglass on the back under the hole??
Then fibreglass from the front.
If any of that makes sense 😉
Thanks.
Bernie.
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BruceS
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Re: Fibreglass.

Post by BruceS »

Bernie do you have a photo? How big is it?
At a guess .... since it's not in a real dangerous place like the bottom of a boat, I'd just scuff the area around the hole with coarse sandpaper, wipe the area well with acetone, mix up your resin & paint all around the hole & then lay a piece of woven cloth over the hole. Then gently brush more resin over the cloth & make sure you push the resin thru the area around the hole until the cloth goes transparent. Let it harden & once it sets give the area a smooth off with sandpaper & if needed give another coat of resin.
Once that goes off, smooth off again & mix up some more resin & add some talcum powder until like thick peanut butter. Coat the whole area with it & let that go off. You can if needed smooth that off with fine emery if needed but for that job no need.
I presume it's not epoxy resin? Not needed!! Polyester resin is best!
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Re: Fibreglass.

Post by jon_d »

Bernie.. I did a bit of glass work in my teens.

1. get some white fiber board and polish the white side with some clear floor wax. Really polished. This is the release agent.
2. feather the hole from the inside.
2a. make sure the entire area is free of dust/dirt
3. somehow attach the fiber board over the hole so there in no gap. And won't pop off when laying in the fibre glass. (white side is touching the new fibre glass)

4. working from inside, paint the hole/white board/ feathered area with gelcoat and let it set.

5. then cut up the glass in shapes to match the hole. Each one getting bigger to overlay onto the feathering.

6, wet up the first piece and the hole with resin and lay it in.
7. work the glass so it's translucent and not white. If it's white the resin hasn't got into the fibres.

8. repeat with the other pieces. But be quick, the resin goes of fairly quickly.

You'll need a tool to work the resin in. Generally, you use a metal roller.
Using too much resin makes it heavy and not strong
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Re: Fibreglass.

Post by BernieQ2 »

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Re: Fibreglass.

Post by supersparky »

I can't add much to what Bruce and Jon have said. If you muck it up it won't stick and you'll know straight away.
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David

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Re: Fibreglass.

Post by T1 Terry »

My bit, because Jon's idea will be very hard with a shape like that. Duct tape across the outside to cover the hole. Feather out the hole from the inside heaps bigger so it looks like a shallow pond slowly drying up, all those layer are wide around the edges ..... only looks like that if it's laid matt construction, if it was just sprayed chopped matt into a mould, no real layered look, but still feather it out over a large area . This is important to make it bond to the substrate and not just crack around the edges and pop back out in the future.
Next is the method Jon put forward, cut lots of pieces, each slightly larger than the last, the shape of the now feather edged hole (it should be larger now than before) till you have enough to build the patch back to the original thickness.
You might need a new layer of duct tape, the sanding probably wrecked it, from the inside, a layer of resin over the sticky side of the duct tape and up the edges, add the smallest piece of cloth matt and dab more resin in until it seems to disappear, a layer of resin over that and repeat until it looks thick enough to allow the piece to be sanded flat. By this time it will be getting fairly warm around the patch, clean up the brush and resin pot, have a beer and congratulate yourself on the progress so far, this is to give the resin time to set up and stop you fiddling with it and/or, trying to take the tape off and finish the job all in one go :lol:
When you think you have had enough of rest away from the job, peal the tape off the outside .... and head back to the beers until tomorrow.
When the fog clears from the night before, sand the inside till you are happy with the finish, sand the outside to get feathered edges and repeat the inside repair process ..... if you sanded it well enough when you did the inside, there is already that feathered edge, so just a light sand and the coat of resin with the talc to make it white enough to blend in .... now leave it alone, the more you mess with it, the more you'll need to fix later ..... the next day it will be fine to do what ever you want to do with it, sand it and paint it or just leave it how it is .... enough words Jon? ;) :lol:

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Re: Fibreglass.

Post by jon_d »

Bernie,

Use a piece from a ice cream container. That will bend to the shape.

Wax it to make sure there is a release agent. (even though the gel coat mat not bind to it.)
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Re: Fibreglass.

Post by BernieQ2 »

Thanks everyone, what sand paper... from start to final sanding.
And I will paint the whole cover when finished.
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Re: Fibreglass.

Post by T1 Terry »

BernieQ2 wrote: Fri Oct 18, 2024 11:59 am Thanks everyone, what sand paper... from start to final sanding.
And I will paint the whole cover when finished.
Home from Gayndah...
Bernie.
The finest you can get on one of the multi sheet sander/grinder discs for the angle grinder, a flapper wheel will not get an even finish and the Scotch brite type pads aren't tough enough to grind fibreglass very well ......

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Re: Fibreglass.

Post by BruceS »

Bernie what cloth or strands are in the kit?
The thing will one day be up & out of site so no need for expert job! I'm guesing your main aim is water proof?
Jees.... just put the 100mph tape back on!!! hehe

EDIT: just had another look at the hole. Are you sure it's fibreglass & not just moulded plastic? Strange to see a neat hole like that in fibreglass.
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