Spider web cracking, at what point......
Thread Starter
Cruising
Joined: Apr 2013
Posts: 13
Likes: 0
Spider web cracking, at what point......
So lots of corvettes I've seen have some amount of spider web cracking from an inch or two in just a couple places, to large amounts of space in multiple areas.
My question is does it always spread like wildfire, and at what point should you do something about it? Does it ever really compromise the integrity of the fiberglass strength in that area or is it strictly paint?
Basically if you purchased a car with a couple small places on it, are you going to need a full paint job? 6months.......6years.....???
Thanks
My question is does it always spread like wildfire, and at what point should you do something about it? Does it ever really compromise the integrity of the fiberglass strength in that area or is it strictly paint?
Basically if you purchased a car with a couple small places on it, are you going to need a full paint job? 6months.......6years.....???
Thanks
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
It is in the fiberglass, which then transferred to the paint . It is usually just cosmetic, and all that is needed is one layer of fiberglass on top of the spider crack. If there are lots of cracks in the same place you are better off grinding the whole surface down and glassing the whole area with one layer. This also applies to gel coat cracks. New panels should be checked for cracks using wash and wipe and a blow gun before any sanding is even done...they are easier to detect this way.
It is usually caused by rocks being thrown up by the tires into the bottom of the fiberglass. I just did a bunch of repair work on an 88 Chevy at work, which is a common problem from the factory. Ground the entire topside down and laid one layer of glass down. We then had the undersides of the box sides bedlined to prevent any future rocks from causing any damage. If they are not glasses and just painted over again, they will show up in a new paint job fairly quickly.
It is usually caused by rocks being thrown up by the tires into the bottom of the fiberglass. I just did a bunch of repair work on an 88 Chevy at work, which is a common problem from the factory. Ground the entire topside down and laid one layer of glass down. We then had the undersides of the box sides bedlined to prevent any future rocks from causing any damage. If they are not glasses and just painted over again, they will show up in a new paint job fairly quickly.
Last edited by stinger12; Apr 11, 2013 at 12:43 AM.
Burning Brakes
Joined: Apr 2012
Posts: 1,084
Likes: 96
From: Bowmanville Ontario
When I had my 79 Firebird painted a long time ago by a friends fathers shop. He told me they added a 'flex agent' to the paint so that it wouldn't spider crack on the rubber bumpers. After I picked up the car, he showed me the remainder of the paint in the can...it had turned to pretty much jello. I never had a spider crack after that until the day I sold it.
Does anyone know if they still have this 'flex agent' out there? If they do, I would use it on my 74 if/when I decide to paint it.
Ken
Does anyone know if they still have this 'flex agent' out there? If they do, I would use it on my 74 if/when I decide to paint it.
Ken
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
When I had my 79 Firebird painted a long time ago by a friends fathers shop. He told me they added a 'flex agent' to the paint so that it wouldn't spider crack on the rubber bumpers. After I picked up the car, he showed me the remainder of the paint in the can...it had turned to pretty much jello. I never had a spider crack after that until the day I sold it.
Does anyone know if they still have this 'flex agent' out there? If they do, I would use it on my 74 if/when I decide to paint it.
Ken
Does anyone know if they still have this 'flex agent' out there? If they do, I would use it on my 74 if/when I decide to paint it.
Ken
Fiberglass is not flexible.
Melting Slicks
Joined: Sep 2010
Posts: 2,413
Likes: 59
From: Emerald Isle NC
I have a vintage Gordon&Smith Fibreflex skateboard that disagrees with you, vehemently.
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
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Safety Car
Joined: Jul 2005
Posts: 3,697
Likes: 833
From: WI
I agree, usually people see cracked paint and translate that into the fiberglass being cracked. Usually it is the 8 layers of paint on top of the fiberglass that fail due to expansion/contraction of the fiberglass from the heat of the sun, cold and what-not. Old paint jobs that use lacquer or enamel are prone to cracking due to age no matter what substrate they were painted over. They were 'hard' paints that didn't have a lot of flex properties. My old Caprice's original paint was severely cracked after 10 years way back in the 90's, and that was original paint over steel.
But it if WERE cracks in the fiberglass, then you need to take care of it during a paint job. Not too difficult, just takes a little more time. Hope this helps.
But it if WERE cracks in the fiberglass, then you need to take care of it during a paint job. Not too difficult, just takes a little more time. Hope this helps.
Last edited by Mark G; Apr 11, 2013 at 08:10 PM.
Thread Starter
Cruising
Joined: Apr 2013
Posts: 13
Likes: 0
A car I have looked at has a couple places right on the nose of the front bumper about 2 inches deep into the bumper and 4 inches wide and a spot the size of a quarter under the door handle on one of the doors. I can live with the issues, just don't want them to become significantly worse in a short period of time.