Thinning gelcoat

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NigelCraig

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I want to deal with some scratches and scuffs in dark blue gelcoat that don't respond to polishing out but are too superficial for a proper repair. I know that if I use gelcoat filler at normal consistency it will end up looking worse than it is now. If it was white or cream I wouldn't bother. Is there any way you can thin gelcoat to sort of "wipe" into the affected areas? If so how does that affect the amount of catalyst to be used?
 
The fibreglass guy in Wilson\s yard on Hayling advocates spray application of gel coat rather than paint as a way to freshen up the appearance.
 
Thoroughly clean out any scratch / gouge / area or sand, apply styrene via a soaked cotton-bud leave for a few minutes & apply Gelcoat (leave for 24hrs.) Use 4 - 6 - 8 - 12 - 1500 (be very careful with the 400 & 600) wet with a pad & water-spray containing a little soap solution (Fairy etc) (thimble full,) keeping wet at all times whilst sanding. Finally use a cutting compound, polish & buff ...... :)
 
OGITD said:
Thoroughly clean out any scratch / gouge / area or sand, apply styrene via a soaked cotton-bud leave for a few minutes & apply Gelcoat (leave for 24hrs.) Use 4 - 6 - 8 - 12 - 1500 (be very careful with the 400 & 600) wet with a pad & water-spray containing a little soap solution (Fairy etc) (thimble full,) keeping wet at all times whilst sanding. Finally use a cutting compound, polish & buff ...... :)
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Does this apply to hairline scratches and, if so, are you saying that it is not necessary to widen the scratch? I assume you are really referring to flowcoat, aren't you? As I understand it, gelcoat needs to be covered to harden.
 
maby said:
As I understand it, gelcoat needs to be covered to harden.
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Not if it contains waxed styrene.

As we all know, the trouble with gel coat repairs on small localised scratches or dings is that the repaired area always has to be enlarged to feather in. A mate of mine has a blue gel-coated day boat and I stole this idea from him. He's a car body repairer by trade, and I saw him filling some scratches on his boat one day with a blue wax crayon. The result once he'd finished with a polish-up was nothing short of amazing. I was seriously impressed. Ok, you could argue that it doesn't have the permanence of a gel repair, but for the odd little scratch, its far quicker, doesn't take such a degree of learned skill, and last but not least... it does the job.
 
nigelmercier said:
AKA Flowcoat, as maby says.
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Supplementary question - as I understand it, the point of adding the wax is to avoid the need to cover the gelcoat in order to allow it to harden. The wax is described as "rising to the surface" and blocking the air in the same way that a piece of clingfilm would do. Does this work if you are filling hairline scratches - which was the original point of this thread? We are talking about very shallow scratches - is there sufficient depth to permit an adequate thickness of wax over the surface of the gelcoat?
 
I would most definitely go with the wax crayon idea. If you widen the scratches you will need to colour match the gelcoat. I was a colour matcher in a previous existence, with a huge number of pigments and electronic equipment to assist me but I assure you it is not easy. With the very limited and strange mixtures of primary colours available to the amateur I predict that it will never look right. Dark blue is always difficult because it fades a lot and the repair will fade differently. Try the crayon first, you have nothing to lose as it will wash out with solvent.
 
For my sins I spend a fair amount of my week repairing gel cracks, crazing, grazes and scratches.
The hardest to fix is thin gelcoat and stained white boats, especially those boats that have had extended periods in inland Dutch waters.

There are a number of ways I fix the problem but each case is different so its hard to give just one method.
In thickish gel I dremel out the scratch and using my RAL cards find or mix a match and gel up using topcoat gel.

With fine cosmetic scratches I fill with a knifing putty and sand back with 1500 or 2000 wet and dry.
I then first try my RAL cards to find a colour match and order a small tin of paint and touch up.

I have one I'm doing now which is Royal Blue fading to nearer Oxford Blue at the waterline.
In this case I've chipped a area of gel out around 25mm sq from the area I need to touch up.
This has been sent yesterday to a local paint matcher and we should get a tin by Tuesday next week.
 
Definitely will try the wax crayon -I have some dark blue gelcoat filler from the builder but even they say it's unlikely to match up exactly after 16 years weathering of the original gelcoat.
 
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