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  1. #1
    grizzly_a58 is offline Chief Bottle Washer and Tea Boy
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    Smile fiberglass, gel coat, resin.

    hi guys , just a quick question, what is the difference between , fiberglass resin, and gelcoat, i am thinking? always a first time. gelcoat has a colourant in it. is it the same as resin, the reason i am asking is, after altering my panels and fiber glassing back together, can i get away with just using resin to fill in any small areas, i am painting my shell , or will it crack or split. cheers, grizz.

  2. #2
    Sidecarbod's Avatar
    Sidecarbod is offline Driving God
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    Quote Originally Posted by grizzly_a58 View Post
    hi guys , just a quick question, what is the difference between , fiberglass resin, and gelcoat, i am thinking? always a first time. gelcoat has a colourant in it. is it the same as resin, the reason i am asking is, after altering my panels and fiber glassing back together, can i get away with just using resin to fill in any small areas, i am painting my shell , or will it crack or split. cheers, grizz.
    In my opinion its OK to not use gel coat.

    My understanding of the stuff it that it produces the fine surface finish when fibreglass parts are made in a mould. It is also easy to shape and sand.

    You can get a very good finish using resin but it just takes time and elbow grease!

    One thing that I will say is that I've never been very happy when trying to join or modify parts using polyester resin, I always use epoxy resin, it sticks like "5hit to a blanket"! The problem is that its bloody hard to sand and bloody expensive.

    Regards,

    Pete
    I refuse to engage in a battle of wits with an unarmed opponent.


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  3. #3
    Deck's Avatar
    Deck is offline Mechanic
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    Now that you've posted about it...if you scroll down you'll find a wealth of knowledge on the subject! Very impressive I think.. But just to confuse you with that dangerous little bit...

    Quick answer:
    There is a difference in chemical composition between Gel and Resin, Gel coat doesn't ever dry on the air surface where as resin does. Its also harder and a bit more brittle.


    Long answer:
    Resin is a bit softer than the gelcoat and in thicker sections there is definately more shrinkage. It is ok to fill cracks and gaps with it but make sure you key up the surfaces well for every layer...cos its so fluid it tends to run out and pool at the bottom so a couple of goes can be needed. Gelcoat is definately better at staying where its put. I've been sanding out holes and stars and the like out of the gelcoat (and sometimes right through!!), then filling with gelcoat in thin layers, 3mm max, and then surfacing with the gelcoat filler. Haven't got a 10 year old example but got some books and met some people who recommended this kind of thing.

    Other people recon car body filler, smooth 7/Isopon, will do all you'll ever need but I don't trust it for building up door edges or the like and I like the extra bonding gelcoat gives.

    I've been trying out a few things and for little cracks and surfacing I've been using Gel coat filler from rswww.com. Its expensive thou and sometimes a bit too thin.

    I've also reasonably sucessfully taken the tack out of gel by mixing 20% resin in with it. There is a special wax impregnated gelcoat (additive?) available but I couldn't find it.

    Its also possible to lay a sheet of plastic, something like .25mm PVC (not thin bags!!) over the gelcoat to get the surface to cure but this is messy!!

    I was told to just wipe the area filled with gelcoat with acetone after its cured to take the tack off but I found this doesn't really work either.

    Hope this helps
    Best of luck
    Cheers
    Dec

  4. #4
    Sidecarbod's Avatar
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    I believe that you can get a gel coat that does cure in air but I don't know what it's called!

    You are right that most gel coats need the absence of air to cure.
    I refuse to engage in a battle of wits with an unarmed opponent.


    Rules for buying 'Go Faster' parts:-

    If it's fast and cheap then it's not good.
    If it's cheap and good then it's not fast.
    If it's good and fast then it's not cheap!

  5. #5
    Purple AK's Avatar
    Purple AK is offline Pit Babe Magnet
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    Quote Originally Posted by Sidecarbod View Post
    I believe that you can get a gel coat that does cure in air but I don't know what it's called!

    You are right that most gel coats need the absence of air to cure.
    It's called TopCoat Gelcoat relies on the release wax of the mould to fully cure. Whereas TopCoat has the wax already mixed in it. Some useful stuff here

    http://www.cfsnet.co.uk/

    http://www.ecfibreglasssupplies.co.uk/store/index.php
    Chris
    AK427 351Cleveland T5WC

  6. #6
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    if youre going to paint it, do not pass go, do not collect 200, go straight to a chandlers and buy epoxy filler!!
    Joking apart its tough, quick settin, doesnt move, sticks to anything and can be sanded smoth; its not too expensive either if youre only after a tube to fill imperfections, and if it will survive years underwater, life on a cob will be a cinch. IMHO
    Regards Steve

  7. #7
    grizzly_a58 is offline Chief Bottle Washer and Tea Boy
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    Thumbs up re fiberglass etc.

    thanks guys, very informative, gives me something to think about , cheers.

  8. #8
    kevchard's Avatar
    kevchard is offline Chief Engineer
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    We have bought a 'bridger', which is fibreglass strands premixed with resin, but then you have to add hardener to make it go off. It has the same properties as fibreglass, goes on like filler and it good to sand and shape afterwards.
    We have bought it from glasplies (advertise in kit car mags). I think it is some thing like 15 for 5 litre size tin.
    I can dig their phone no. out if you like.
    Cheers
    Kevin
    PS That is the last thing we need, you on strong fibreglass fumes, then posting comments on here
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