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How can i repair stone chips on my Westfield?


perksy

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Perksy - I'm supprised you didn't answer this yourself - as you got plenty of info the last time you asked :p  - but here's what I posted last time - plus other bits from along the way ....

For anybody interested in using gelcoat (I had a thread going on the old BBS about this), I've now successfully filled the holes in the side panels left by the clamshells, and have a few tips out of the experience:

1) The hardner required for the gelcoat is Methyl Ethyl Ketone Peroxide - sold as Butanox M50 or Scott Bader Catalyst M. The ratio is officially 2% by weight, but 2% by vol is near enough. Scott Bader's local agent for the NW is in Denton (0161 336 0766), I got mine from Stevens at Sandbach (01270 529111) - they gave me some good technical advice as well

2) According to Bridget Ringrose at Scott Bader, "The repair should be carried out in dry conditions with a minimum continuous temperature of 15 Deg. C. The moulding should be kept in these conditions for a minimum of week". I was working in a garage with a fan heater, the temperature was around 15 C most of the time for the initial gelling, but may have dropped overnight - so far I've not had a problem with it.

3) I turned my gelcoat into 'flowcoat' by the addition of 2% vol of wax - what Stevens describe as 'Tack free solution', this meant that I could just leave the surface of the 'gelcoat' open to the air, and it would 'dry' rather than remaining tacky  - a lot easier than having to seal the surface!

4) I prepared the panels by chamfering the edges of the holes to make sure there was no loose gelcoat (in some cases this meant making the holes a bit bigger , as the original holes weren't that tidy), and 'carving out' cracks in the gelcoat, so that the new coat could bond.

5) I patched the inside of the holes with a piece of fiberglass mat to give a surface to work fill onto. I also built up the depth in the holes a little with some isopon p40 - for smaller holes I just used the p40.

6) For measuring out the hardner & wax I bought a couple of 'baby medicine syringes' (used for squirting nasty medicines into the mouths of screaming brats! ) from the local chemist - a couple of quick checks told me that it was approximately 30 drops per ml, so 3 drops per 0.1 ml.

7) I made up small batches of gelcoat, of 20 ml of resin and 0.4 ml of hardner & wax (12 drops each), which started to gel (and become unworkable) in about 20-30 mins. I rarely used more than about 1/4 of what I had made, but smaller batches were too awkward to measure accurately.

8) I applied the first coat of gelcoat on the hole using a plastic spatula, leveling off the surface with a flat edge. After this had dried (gave it a day or so), I flattened the surface down with a stanley knife blade (this isn't Blue Peter so I can use the real name!  ), scraping it across the surface, and checked there were no 'edges' showing through - if there were - it was a case of cutting them back as with previous 'cracks'. the surface was also 'scratched' to give a better surface for the next layer to bond to.

9) the next (final) coat of gelcoat was applied with a brush (there is a small amount of shrinkage in the gelcoat, so the surface won't be flat after the 1st coat if the gelcoat was quite thick), and deliberately applied it to raise the surface above the panel. When this layer has dried, the surface was again levelled with the stanley knife blade, and then sanded with 800 grade wet & dry. (I did go as far as trying 2000 grade w&d - but didn't get any better results over 800)

10) The final polish was done using Brasso which gives you back the deep shine

I also got asked about 'star cracks' in the thread :

I did a couple of them on the main body (not wings - as they'd just been replaced and so were unmarked - going to coat them on the underside with latex paint - yumee!!  ) - I mentioned them in the main post as 'cracks'.

You need to carve out along the lines of the crack to give a small 'V' (only just go through the gelcoat layer if you can) so that the gelcoat can bond.

You're probably best levelling down the painted surface with wet & dry for these fine cracks as using a stanley knife blade can 'pull' the gelcoat out of these cracks (I found this out the hard way!  )

If the cracks are on the wings - you may be best putting a glass fibre matting patch on the underside of the wing as well, as you may have lost a bit of strength there.

And from what Perksy found out before ...

I've spoken to a Helpful chap at ABL (stevens) in Sandbach, Cheshire.

They supply Resins,GRP etc, his advice was to use an Epoxy resin, a Catalyst and the coloured Gel coat because "Epoxy adheres much better than Polyester..."

HTH

Steve

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  • 2 months later...

Excellent advice from Steve, carried out a couple of repairs yesterday and am really pleased with the results. :D  :D

Went the Flowcoat method and got catalyst and wax from Stevens, plus a few bits for mixing. The chap at Stevens reckoned you can speed up the curing by heating the repair with a fan heater, did this and it was dry and ready for shaping in about an hour and a half.

For me this was a really useful FAQ   :t-up:   :t-up:

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Perksy - I'm supprised you didn't answer this yourself - as you got plenty of info the last time you asked :p

But he's not asking how to repair holes left by the clam shell brackets here, but how to repair stone chips on the bodywork.   :)

I intend to have a go at repairing these with wet and dry starting with 500 grade and working down to 1200, then T cutting and polishing. It's amazing what you can repair with this method. I got excellent results getting rid of the deep scrapes left by 15 years of the side doors being opened and closed, so I'm sure it'll work with stone chips.

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No experience of repairing chips in cars but in order to repair chips in boats used to use sellotape to exclude the air.  Needs an accurate amount of gelcoat blobbed over the chip to fill it flush and then just put some sellotape over the top to seal it from the air and match the profile of the surrounding area.  No rubbing down required.  ;)  ;)

Rory's Dad

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  • 2 years later...

I did very similar to all above

purchased chrome yellow gell coat from WSC then purchased Organic Peroxide from a local boat builder and followed normal preperation tips, once hard after a day or so used 2000 wet/dry and got a mirror finish....  excellent....

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  • 2 years later...

just reading the great advice above as I have some holes and cracks that really need looking at

how saitifactory are the results - i.e. if you take your time and buy the gel from the factory is it possible to fix to a level where you cannot see the repair or are there issues with colour matching and gel thickness that stops a 100% finish?

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There are potential colour match issues, even with black, bought from the factory  :blush:

From experience though, I found that apart from the obvious - make sure that you stir your tub REALLY thoroughly, very careful attention to the ratio of catalyst seemed to make a difference. At 2% catalyst, and 2% styrene solution, (to make air-hardening flow coat) I was getting very, very dark greys that definitely stood out.

By loosing the styrene solution and reducing the catalyst proportion slightly I got much better "colour" matches.

To be fair, as you're needing to overfill the holes and sand back anyway, the lack of proper flow coat seemed to not be an issue.

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Cover them in a black strip Cleggy with durance written on it, it will be lovely.

p**s off :laugh:  :p

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