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-   -   Glass Fibre Repairs And Finishing (http://www.madabout-kitcars.com/forum/showthread.php?t=7398)

cbjroms 17th March 2021 10:02

Glass Fibre Repairs And Finishing
 
I have been watching a guy on YouTube repairing hurricane damaged catamarans in the US. It is really intresting to see the fantasitc finishes that he achieves such that the boats look like new are are better built (rebuilt) than when they left the factory.

In the latest episode, having 'long-boarded' the huls to get a smooth surface he then uses a spary gun to apply a couple of layers of gelcoat followed by a final layer which is a mix of gelcoat and wax.

Wondering whether this would be a better final finish option than sparying paint. Would gelcoat be a much thicker layer (and hence more forgiving) than paint?

molleur 17th March 2021 11:10

20-28 mils thickness is the norm for gelcoat thickness. Much thicker than paint. It is not particularly UV stable and will require
buffing almost yearly from fading. A proper paint job on a fiberglass automobile body would be better. IMO

redratbike 17th March 2021 22:38

would a ceramic protection product save the gel coat fading ?

molleur 17th March 2021 22:44

probably, but why go through trouble and effort for expensive ceramic coatings
that also need to be replenished, and tedious gelcoat polishing when a simple paint job would be okay.

JG 22nd March 2021 10:12

My cobra rep had a gel coat finish and it was great but imperfect.

Didn't suffer any fading over 10 years or so and didn't do any more than wax it after the initial surface prep.

Trouble was it was imperfect and whilst not noticeable from a few feet away, I knew the imperfections were there. Things like mould lines not fully filled with gel coat, pinholes, star crack from delivery (grrr). Any repair I did with a pot of gelcoat from the supplier ended up with a dark 'ring' around the repair area and seemingly no way of getting rid.

Surface prep is key as well. As it came, you could see the impression of the chopped strand matt through the gelcoat, a bit like orange peel for paint, so the entire bodywork needed wet sanding in various grades and polishes until it had all gone (to be fair I would do the same with a paint finish to get rid of orange peel) but the resulting finish was worth it.

I'd choose gel coat again on a budget build as long as I could see examples of the manufactures out of the mould finish but for me the next project will be painted.

Mister Towed 24th March 2021 15:44

Paint all the way for me, every gel coat finish I've seen had a sort of matt sheen to it even when polished.

Prep is key on fibreglass though (no pun intended). Once the surface is fully flatted, dried and degreased use an etch primer then flat that back and follow up with several coats of high-build primer. Once they're flatted, the top coats should be automotive cellulose as it's flexible and more resistant to cracking than two-pack so is better suited to a car made up of comparatively wobbly fibreglass panels.

Cellulose is easy to use for an amateur sprayer and there isn't much you can't put right if you make a mess of it. Runs and drips are easily sanded out and repairs can be blended into existing paint if necessary, which is much more difficult with two-pack. It doesn't have that modern shiny plastic look to it once it's polished, either. Oh, and two-pack is a deadly poison if you breathe it in without wearing the right mask or forced-air breathing apparatus.

kon 25th March 2021 08:51

Quote:

Originally Posted by Mister Towed (Post 106193)
Cellulose... doesn't have that modern shiny plastic look to it once it's polished, either.

Interesting point... I think I'm going to want the modern shiny look... do you know if putting a clear-coat over the top is enough to give it the modern sheen, while still retaining the flexibility?

Mister Towed 26th March 2021 20:24

Sorry, I haven't tried clear coat over cellulose. I use wet and dry, 800 to smooth out any runs or drips, then all the way from 1000 to 2500 grit. Farecla G3 cutting compound takes out any swirls, then a final polish with Autoglym Super Resin leaves it shiny. Works for me :)

Here are my efforts at amateur spraying, achieved with a bit of internet research, some advice from a pro, a cheap compressor, Jawel cellulose paint and a 150 spraygun -

https://i.ibb.co/qxwBrXN/P1050161-zpsgjsrhd0y.jpg

https://i.ibb.co/7vvd05J/IMG-20201218-083941039.jpg

What are you spraying that needs a modern look to the finish?

kon 29th March 2021 08:22

Quote:

Originally Posted by Mister Towed (Post 106200)
What are you spraying that needs a modern look to the finish?

I'm not quite ready to give away all my secrets just yet, as still buying bits, and planning the details of the rear end. I'm finding it very hard to decide on a set of rear lights. Happy/sad news with my Grandfathers passing, I have some inheritance coming, so hopefully this summer I can finally start a build thread. It wont technically be a Tribute, but inspired by the same ideal, based around a modern-ish (2005-2008) Ford. It will probably end up silver (147) or metallic grey (LD7X), with dark red or BRG stripes.

Mister Towed 29th March 2021 17:48

Sounds good, silver and metallic grey are two of my favourite car colours.

Sorry to hear about your Grandfather, it's always sad when a family elder passes.

Mitchelkitman 29th March 2021 18:59

Quote:

Originally Posted by kon (Post 106216)
I'm not quite ready to give away all my secrets just yet, as still buying bits, and planning the details of the rear end. I'm finding it very hard to decide on a set of rear lights. Happy/sad news with my Grandfathers passing, I have some inheritance coming, so hopefully this summer I can finally start a build thread. It wont technically be a Tribute, but inspired by the same ideal, based around a modern-ish (2005-2008) Ford. It will probably end up silver (147) or metallic grey (LD7X), with dark red or BRG stripes.

I can't think of which vehicle, unless it was 2003-2005?


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