Need assistance from the collective wisdom of the board (cracks in fiberglass)

[Wayne 962]

Okay, so an unspecified family member (non-blood related, and non-wife), came over and sat on something that they shouldn't have sat on today, breaking / cracking it in the process. This thing that they should not have sat on is made out of fiberglass, is painted white with a near-concours paint job, and in general is pretty expensive. After calming down and regaining my composure, I figured that it would be best to ask the collective wisdom of the board on how to best try to fix this problem. Unfortunately, I don't have photos.

So, what I have is a large, semi-flexible piece of fiberglass with some "hairline" cracks in them now. Since the car is white, and the underlying fiberglass is dark, these cracks show up as black. I'm hoping that there might be some product out there (maybe Corvette owners would know) that you can use that is colored white that will "fill" in the crack (like a colored polish or something like that and at least cosmetically make it semi-go-away.

Thanks in advance,

Wayne

[bell]

one thing i've learned with fiberglass.....when the painted surface is cracked you're screwed....
i've tried sanding and repainting etc....unless you re-apply some sort of resin the crack will remain....

maybe buffing the area a inject a white power into the cracks? then wax/polish?

[Joe Bob]

Not in my experience.....light putty, sand and paint.....

I'm sure others will have an opinion....

[kidrock]

Since you live near the coast, visit a local surfboard shop that does repairs and ask for white pigment. Regular white pigment for the polyurethane resin should do the trick, but you could always mix other pigments so you can color match as best as possible.

Since you describe your damage as "hairline cracks", I would not use fibreglass cloth over the cracks. However, you can add finely-chopped fibreglass cloth to the polyurethane resin and catalyst to strengthen your repair....and it will aid in the "whitening" of your repair. Small bags of this can also be purchased at your local surf shop.

P.S.---DO NOT LET ANYONE TALK YOU INTO PURCHASING "SOLAREZ" FIBREGLASS REPAIR.

Sorry I'm not closer, I'd do it gratis....practically done it all my life. Let me know if you want more DIY info, and I'll include a step-by-step detail on this thread.

[jimtweet]

this is going to be hard to explain, i have done alot of fiberglass work...

it sounds like what cracked is the gel coat...it is going to have to be stripped of paint to start fresh

you want to take a utility knife (razor blade) and run it down the cracks holding the blade vertically . run right to left, and then run left to right on both "sides of the crack.

You want to start about a 1/8" before the crack, and extend pass the cracks

you are essentially creating a "V" where the crack used to be, if you dont get rid of the gel coat around it, its just going to keep cracking and spreading

once this is done, you are going to want to sand with like a 60-80grit. the whole surrounding area...

this is where you will hear two different ways to proceed...

1. (i just did this on my own bumper and have been good for a year) i just used some high end body filler and sanded back smooth

2. some will say to use chop mat and some resin to create a patch. I have also heard of people drilling some really small holes around the area and then using the resin and chop mat. the resin will sink into the holes and hold it all together better....

i guess this really depends how bad the cracks are, i am hope i helped man...there used to be a good video on youtube about this.

[jimtweet]

Fiberglass Kit Car Repairs-Gelcoat Stress Cracks Fixed The Easy Way! - YouTube

[Wayne 962]

Hmm, is there some type of pre-pigmented white resin type of stuff that I can rub into the crack?

-Wayne

[Danny_Ocean]

This is what we use to repair gelcoat dings on boats. Excellent product, but matching the color is the hardest part.

Match N Patch Large Gelcoat Repair Kit (Evercoat) - Gelcoat Repair Kits

[Quicksilver]

If it is cosmetic then jimtweet's advice seems sound but...
Getting a paint match is going to take a top level autobody person. If it was mine and it was cosmetic I would talk to Sterling Collision Center in Tustin. They are used to working with stuff worth way north of $100K, they don't charge a 'snob tax' and they don't accept anything except perfection.

Not sure where the damage is and how critical to the structure the damaged area is. If there is worry about a possible structural issue then probably the best option is talking to someone who is an A&P competent in repair of homebuilt aircraft. Any repairs that they have to do are absolutely required to be structurally sound. With the number of foam/E-glass composite planes (such as Rutan designs) out there I would suspect you would have a number of people available at the Torrance airport and probably a lot more at the Fullerton airport. A call to Rutan wouldn't be a bad idea either.

If you want to see directly what is involved in doing a structural fiber composite repair look into West Marine's "West System" epoxy composite repair. You cannot put polyester resin over polyester but you can put epoxy over either polyester or epoxy. The rule of thumb for full strength structural repairs is to grind into the crack as deep the composite is damaged and bevel the sides of the damaged area at a 12 to 1 slope. For example if you have an 1/8" crack you will need to bevel it at least 1.5" to each side. Getting it flat will take a hole bunch of incredibly artistic elbow grease. (Vacuum bagging will help.)
I did a patch on one of my catamaran hulls and it isn't that hard to do the epoxy but making it look good is beyond my ham-handed abilities. There are lots of good boat and airframe related tutorials about West System. There is a good starter link: WEST SYSTEM | Projects | Fiberglass Boat Repair and Restoration - WEST SYSTEM epoxy for fiberglass repair

[Quicksilver]

Originally Posted by jimtweet

Fiberglass Kit Car Repairs-Gelcoat Stress Cracks Fixed The Easy Way! - YouTube

Fun to watch. The guy is total comedy. He has an opinion!
(not to say he isn't skilled...)

[jimtweet]

Originally Posted by Quicksilver

Fun to watch. The guy is total comedy. He has an opinion!
(not to say he isn't skilled...)

by no means am i saying this guy is the best in the world, but i was told how to do this first hand by a old body guy, a week after i did it, i saw this video online and it was basically the same thing i was told...just gives you the idea on how to do it.

[Quicksilver]

Originally Posted by jimtweet

by no means am i saying this guy is the best in the world, but i was told how to do this first hand by a old body guy, a week after i did it, i saw this video online and it was basically the same thing i was told...just gives you the idea on how to do it.

Sorry, didn't mean to give the impression that the guy in the video wasn't technically proficient. Watching the care and precision with which he mixed and applied the filler tells me he has done it a billion times and his hands can do it themselves.

But the color commentary is priceless!

[dsfnctn]

The composite structure moves and the gel coat doesn't so what you have is stress cracks from the gelcoat. Look for a good boat repair yard. Gelcoat is made to be color matched sprayed and then wet sand and polished. The trick is to have an experienced gel coat color matched by a person that can account for the color change down the road as it will change

[stownsen914]

One thing to keep in mind is that the fiberlgass (or kevlar or carbon) structure under the gel coat may have been weakened by the "sitting event" too. One thing you might want to consider is laying up a couple layers of whatever composite cloth was used to originally make the part. This would be on the underside of the part (assuming it's exposed and accessible). Once cracks start, they will of course tend to propagate, so it might help prevent that to strengthen the immediate damaged area.

Scott

[H-viken]

+1 for someone who knows how to repair boats (in general guys repairing surfboards don't use gelcoat). They should be able to sort it out.

[j911brick]

Good Corvette shops have mastered this over the years. Take it there. There is no quick wipe on/wipe off solution. The crack will always reappear (sooner than later) with any quick solution. The best way though is to make a new part if you can.

[porwolf]

Coming from the windsurfing experience I know that the board shells are made in reverse molds with the first application of an opaque gelcoat, usually white, and then layers of epoxy drenched fiberglass and/or carbon or kevlar material. So the first layer is the "gelcoat", usualy white opaque polyester resin based. That can be gotten from the right sources. Once the cracked area is reinforced from the back side to be physically inflexible the white gelcoat could be applied to the that crack and sanded and polished out, I think.

[Mahler9th]

I hope that you find a simple approach that meets your needs in terms of time and money expense versus results obtained.

I have done a bunch of fiberglass work on my own race car, but I don't know any methods or materials for something like what you have described. Those types of blemishes aren't an issue for me.

If I were in your situation, and if it related to a Porsche car, I might ping folks with Porsche fiberglass experience. For example the guys at JWE (Rich) or Canepa.

[HawgRyder]

For future possible problems with mis-applied body parts....perhaps a sign or sticker that indicates "NO STEP...or NO SIT" might be in order.
Bob

[Dave Colangelo]

Coming from the boating world where a crack could mean you are at the bottom of the ocean as well as the car panel world here is my 2 cents

If the panel can be obtained easily, get another, paint it the same color, and put it on. As it sounds like the panel is off a car in your garage, I would guess getting a replacement is not that simple.

You could always consider fabricating a panel. Making a mold or wet laying it, this of course requires time and money typically a lot of one or the other.

In terms of patching you could sand the paint off, get some resin and possibly another layer of glass over it. Sand it, for all eternity. Then respray the panel. This will most likely be the easiest option.

It sounds like this is either a concourse or display car so the option to just leave it is most likely out. As a college student who has little money for a very pricey hobby, I have developed a very large tolerance for aesthetic imperfections as long as every thing is mechanically sound. That being said I understand the desire for perfection with these things.

Regards
Dave