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Re: Fiberglass repair

PostPosted: Fri Jan 18, 2019 12:07 pm
by nmauduit
obviously the car has been repainted at some point, at least once. Whether there were some damage to fix and their extent is to be assessed by close scrutiny of the body, inside out (not always easy to photograph).
An other common defect on figerblass cars is osmosis, which produces small bubbles on the paint.

If your car is free of both (poor) repair and osmosis, you're one of the lucky few elligible for an easy paint job - still requiring tens of hours in preparation though... some localized sanding may help you decide if the surface structure (middle photo) results just from a poor priming/paint application (or poor paint quality etc) of from a deeper cause (e.g. underlying fiberglass showing through, that is no gelcoat there - which could be the result of a hasty mechanical sanding off of the gelcoat for a cheap repaint job, and subsequent need at least to reseal properly after checking that indeed the fiberglass has retained its integrity).

As for gelcoat cracks (stress induced like the one near the boot hinges), the issue is not only that the gelcoat no longer protects the fiberglass body (esp. against capillary water absorption) but also that the crack extends into it and weakens it : if not repaired to the proper extent in width and depth, the crak will come back rather quickly. It may be a good idea to reinforce the stressed area - but this must be done in a way that does not just push the stress somewhere else where a new crack will develop... the flexible nature of the body must be maintained for a durable repair (feathering the patches etc).

Again, one difficulty is to set your goal (partial repair vs. complete restauration), as you'll know when you start but not when you'll end...

good luck !

Re: Fiberglass repair

PostPosted: Fri Jan 18, 2019 3:46 pm
by denicholls2
There's lots of good general advice above. Part of the problem is that apparently differing opinions are correct in their context.

My read of your photos is that you have multiple layers of paint and they have interacted with each other. Get some sandpaper and take a small area off and you'll have a conclusive answer, but outside of physical damage I doubt you have a gelcoat problem. There is a lot of talk about pinhole bubbles in gelcoat, but I don't know they are all that common. They aren't in my experience, but it's limited with Loti, much deeper with small boats.

The couple of recommendations I would make are : Stick with strand mat and polyester. I say this because epoxy is stronger and it's a bear to feather. As a beginner, polyester is still plenty hard. It's already been said that the basic repair wants to be dry and dense, a wet coat is the last step after building. Think of polyester as cement and strand as re-bar. They are good equivalents; like cement without something to give it strength in tension, polyester is just thin, brittle plastic. Especially after 50 years. :wink:

Most paint problems boil down to adhesion. The upper layers in your photos have failed to adhere to the lower ones. There's a bit of evidence of chemical interaction as well. With fiberglass shells, it's always best to go down to the gelcoat -- you're going to get an inferior quality paint job any other way because paint just doesn't adhere as well to polyester as to metal. Sometimes, as with my Europa, a respray will look quite pretty for awhile. Shrinkage, particularly in direct sunlight, accelerates deterioration.

The other aspect is that resprays look wrong. Just the thickness required to change color (and smooth any flaws) is noticeable to the eye in rounding of the underlying detail. If you're passing the car on as a flip, then the significant expense to do it right might not be justified. Otherwise, you (and the FO) will appreciate doing it the right way. Getting those layers of gunk off to do the job right will be a lot of effort down the road.

However you get there after your fixes, you need to make sure that all of that paraffin is gone before paint goes on. I would personally use both fine sanding and deglossing solvents, others don't like the idea of the solvents soaking into the surface. Serious examples of water or solvent retention manifest as blisters, usually about the size of a quarter. My Europa has localized blistering on an otherwise pretty good respray. I didn't do the job, so can't be sure why, but I'd guess water. If you use solvents, give them lots of time to evaporate before the primer goes on.

Re: Fiberglass repair

PostPosted: Fri Jan 18, 2019 5:47 pm
by tomjones20194
Thanks to all for the advice. Really good info here. I?ll post pics and update my build thread as I get going on this.

Re: Fiberglass repair

PostPosted: Sun Jan 20, 2019 9:02 pm
by nrwian
West Epoxy is a great product for repairing wooden boats . I would not use it for a body repair , it has a low heat distortion temperature so not great if you paint your car a dark colour . Stick with Vinylester you should not have any issues with that . Also if you use epoxy you typically can't go over it with say a Vinyl or polyester resin system .

Re: Fiberglass repair

PostPosted: Mon Jan 21, 2019 6:42 am
by mark030358
Second photo is caused where gel coat has been removed and surface not properly prepped after.
I had a Europa twin cam like this, where if you looked very very carefully you could see the strands in the fibre glass (on the bonnet) A well know Europa aficionado explained this to me....


Re: Fiberglass repair

PostPosted: Sat Jan 26, 2019 1:34 pm
by tomjones20194
I?ve finally managed to remove all of the interior panels that the carpet attaches to. I would like to replace the cardboards with fiberglass versions before replacing the carpeting. Since I don?t have any molds, I was thinking of coating one side of the panels with wax and then layering up fiberglass to match the same thickness. The wax should allow me to remove the fiberglass once it?s cured. Good plan? Thoughts??

Re: Fiberglass repair

PostPosted: Sat Jan 26, 2019 5:00 pm
by prezoom
After waxing, spray the parts with PVA, polyvinyl alcohol, as a release agent. Your mold will release without damaging the original part.

Re: Fiberglass repair

PostPosted: Sat Jan 26, 2019 8:26 pm
by tomjones20194
prezoom wrote:After waxing, spray the parts with PVA, polyvinyl alcohol, as a release agent. Your mold will release without damaging the original part.

Great - thanks for the advice. Will post some pics when I?m done.

Re: Fiberglass repair

PostPosted: Sun Jan 27, 2019 1:57 am
by prezoom
Forgot to add, it is water soluble so easy to clean up.

Re: Fiberglass repair

PostPosted: Fri Feb 01, 2019 3:32 pm
by rcombs
I used West System epoxy on my car because epoxy is supposed to have better strength and adhesion. I also used West System fairing powder to thicken the epoxy for use as a filler. Since I don't have any road time on the car yet I can't confirm the above statement; however it is used on boats and airplanes.

The fairing powder works better than polyester filler, and since you mix it yourself you can mix it as thick or thin as you like. Having it thin is nice when you are doing the final block sanding.


Re: Fiberglass repair

PostPosted: Fri Feb 01, 2019 3:53 pm
by disquek
West Systems is excellent stuff and will hold up better than just about any other product on a car for composite repairs..

There are no heat related issues as reported earlier in this thread.

I've used it extensively on racing car bodies for the last 20+ years and never ever had any heat related or other issues.

It is always my go-to for any composite (carbon, kevlar, glass, etc) repairs. Honestly, poly resin's only upside is cost. It softens in heat, and never really gets hard. Some racers see this inherent flexibility as an advantage as it can take a hit and crank less. But I never did.

Rejoice. You made the right resin choice.

For body putty, I have used the west epoxy with faring compound. But it's heavy and hard to sand. Kitty Hair (also called Tiger Hair) works great and resists cracking.


Re: Fiberglass repair

PostPosted: Fri Feb 01, 2019 4:21 pm
by Bud English
Another plus for the West System and other epoxies is that they don't dissolve the plastics used extensively on the interior trim pieces around the dash, and the center console. The epoxy does stick well to these pieces. I believe that they are a polystyrene material. That's handy for making repairs there.

As for the fairing compound, the instructions say to wet out the area being repaired with straight mixed resin before applying the fairing compound. This is critical for fairing compound that is mixed to a thick paste otherwise the compound isn't "wet enough" to form a good bond with the surface being repaired. That's important as I quickly learned. I found this stuff fairly easy to sand mainly because it sands clean and doesn't clog the sandpaper.

Follow the instructions and this system works great.

Re: Fiberglass repair

PostPosted: Fri Feb 01, 2019 5:15 pm
by StressCraxx
I usually think of myself as the "King -o-Cheap". It's easy to pay too much and it's unwise to pay too little. Fiberglass work is so time consuming and the effort required to obtain a good result is high. There is value in using materials of consistent quality with good tech support.

The consequences of a repair bodge appearing after the final coat and polish really suck.

Re: Fiberglass repair

PostPosted: Fri Feb 01, 2019 6:59 pm
by Mike Ostrov
Hi, Tom. Having a bit of composite construction and repair over the past 38 years for my Climax Elites, Sevens, some Europas and Elans, it would be impossible to offer any instruction.on the forum.

All the comments have excellent merit.

If I can assist you, just give a call 510-232-7764 anytime.

Cheers. Mike, in Richmond, CA (near SF).

PS: I do paint my cars,

Re: Fiberglass repair

PostPosted: Sun Apr 07, 2019 10:01 pm
by nrwian
I am a boat builds so have used various resins all my working life . I am about to start the body work on the S3 I am restoring . I would use epoxy for all the structural repairs as it sticks really well to the old polyester . And use Vinylester ester on the exterior repairs as its has a similiar shrinkage and heatdistortions temp (HDT)to the old polyester . Epoxy has a low HDT so if the exterior of the car gets hot you will see the repairs . Worse on dark colours in hot climates .