Coating fibreglass bonnet?

[R1 Indy]

Basically I've been repairing my fibreglass bonnet (after it had an accident).

I've been researching all different methods of coating, gel coat, flow coat, wrapping or just standard primer and paint.

My biggest problem here is I don't have a lot of money, so needs to be as cheap as possible. And seems I could buy a whole new bonnet for £200, but I wanted a go at fibreglassing

Here is bonnet in question



Im thinking getting a body shop to paint it would not be economical.

Do you think I could get a half decent job with spray cans?

My understanding is flow coat/ topcoat will come out quite dull?

So anyone got any advice?

Cheers

[anonymous-user]

I had my boot lid gel coated and its very very shiny.

[Big Fat Fatty]

If you coat it properly with Gel and it's thick and smooth enough, then sanding and polishing will be enough to bring it back up to good shine. Smoothness is the key as it'll save time sanding, how will you be applying the gel?

If you can, use an orbital sander and then with wet and dry go down to about 1200/2000 grit, you can then start polishing with compounds to bring the colour and shine back.

Edited by Big Fat Fatty on Tuesday 12th February 13:09

[R1 Indy]

Thanks, gelcoat is what I would like to use, but am a bit confused as to how to the process of applying it ontop, rather than in a mould as its generally used.

Mainly once I've applied to gel coat, do I then need to add something else to make it cure?

[zetec_s6]

The gel coat I've used in the past came in 2 parts that when mixed harden, although from memory you have to seal it from air to get it to harden. Having repaired my rear wing I found the gel coat was a different colour so sprayed it instead, with good prep, sanding and polishing you wouldn't have known afterwards.

[R1 Indy]

Yes, looks like you mix the gel coat and a catalyst. Then looks like I need to apply a releasing agent which makes it cure.

Then can it be sanded smooth, after it's fully cured?

[zetec_s6]

Yes, it's easy to sand and then polish, it's a similar hardness to normal body filler.

[zetec_s6]

When I did my wing I didn't coat the whole thing, i used a dremmel to cut the cracked gelcoat back to the base matting and then filled the channels with the gelcoat.

If you coat a whole panel do you paint it on with a brush and then sand/polish it smooth?

[Big Fat Fatty]

You won't need a releasing agent in this case, that is really only used when moulding.

The Gel coat does need a catalyst but there are certain types (which I'm not greatly familar with tbh) that cure on their own. I used to mould fibreglass for a living and we used to mix about a kilo of gel to about 30ml of catalyst but again it would depend on which type of gel you're using and how quickly you want it to cure (which depends on how fast/skilled with it you are as well). Too fast and you'll leave lumps of hard gel in the coat, too slow and it'll takes days to go off.

Have a practice first would be my advice, just lay some on a board to see what ratio you need it in.

zetec_s6 said:

If you coat a whole panel do you paint it on with a brush and then sand/polish it smooth?

Generally, yes but there are other ways. You could thin it down and spray it but that's a similar process to painting.

Edited by Big Fat Fatty on Tuesday 12th February 13:58

[Major Fallout]

Just my 10p worth but if you can get a color match spraying it would be much easeyer.

If you gelcoat it, there will be about 10 hours of sanding and polishing to do.

[R1 Indy]

Thanks, thinking of ready mixed gel coat from here :

http://www.ecfibreglasssupplies.co.uk/p-1871-polye...

They sell 3 types of catalyst, fast, medium and slow. If I go for the medium.

I will have a good practice on an old piece of fibreglass first.

Also do I try and apply in 1 coat? Or several lighter coats?

[Big Fat Fatty]

Several coats would be best in this situation, as I said, smoothness is the key and you'll get a better result with lighter coats letting it fully cure and giving it a quick key before applying the next.

Also, (this has caught me out a few times before) be careful not to get any debris in the gel while it's curing, including gel dust from sanding. A black spec buried deep between coats will ruin the job and frustrate the hell out of you

[zetec_s6]

I would be a bit worried about the colour match if buying it from someone other than the manuafacturer. I got mine from Tiger and it was still a different colour to the car. Personally I'd take an offcut to a paint supplier to get a colour matched aerosol and just spray it.

[mph1977]

yes you can repair gelcoat with more gelcoat , however it is not paint.

generally you'd use gelcoat to repair scrapes or small areas of impact damage

gelcoat does not cure hard in the presence of air - this is so when it's applied to a mould for a new moulding the laminate bonds to gel coat.

to get gelcoat to set hard when used for repairs you either mix wax in or exclude the air from the outer seurface

[mph1977]

zetec_s6 said:

When I did my wing I didn't coat the whole thing, i used a dremmel to cut the cracked gelcoat back to the base matting and then filled the channels with the gelcoat.

If you coat a whole panel do you paint it on with a brush and then sand/polish it smooth?

that's the sort of thing that gelcoat with wax additive is great for doing ...

[Big Fat Fatty]

That's a good point MPH, and one I had forgotten

R1, you'll need something like this:
http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__Wa...

[R1 Indy]

Ah now it's making sense. So I mix this in at 2%? Also do I add this to all coats? Or just the final coat?

[Big Fat Fatty]

You'll need to add it to all coats and each will need a good key before the next goes on.

Good luck with it, ask questions if you need to.

[R1 Indy]

Many thanks, I thinking know what I'm doing know.