Bodywork, Paint, Interior, Trim, & Wiring

discussions about bodywork, paint, interiors, trim, audio, electrical components, wiring, etc.

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pspeaks
Paul Speaks
Dallas, Texas
(698 posts)

Registered:
07/20/2009 06:40PM

Main British Car:
1972 MGB-GT 1979 Ford 302

authors avatar
Fiberglass
Posted by: pspeaks
Date: February 19, 2012 07:35AM

I have done a great deal of fiberglass work in the past and from time to time have become painfully aware that resin doesn't like raw metal. I have also noticed that a lot of you have installed front and rear valances. Are they fiberglass or metal, and if glass, do you prep the metal surface with something or just hope it works?

Paul


DC Townsend
David Townsend
Vermont
(406 posts)

Registered:
11/21/2007 12:22PM

Main British Car:
'78 B (almost done) 30-over SBF, dry sump

authors avatar
Re: Fiberglass
Posted by: DC Townsend
Date: February 19, 2012 12:46PM

My rear valance is glass. After mounting it, I blended in the seams using glass tape. I first prepped the metal by sanding it with #60 grit paper which I have found really helps the resin get a solid purchase. Before glassing the seam I also thoroughly washed the area with a degreaser. In my case I partial to Prepsol but don't think it really matters which brand you use.

After applying the glass tape and resin, I rolled it thoroughly to help embed the resin better and to eliminate any air pockets or bubbles then used a conventional plastic filler to finish the job.

Since going to this method (I too have learned several painful lessons about glass and metal) I haven't experienced any delaminating issues or ghost seams coming through paint at a later date. While I can't definitively say that my success is due to having a surface that the offers good 'grip' or to giving the resin a mating surface free from contaminants what I can say is, that in combination, this method has worked very well for me.

Given that you have a goodly bit of prior experience with glass work this next comment is probably not necessary but, for those who might read this and for whom this might their first time with this sort of thing, I have also found that the quality of the materials used makes a big difference in the integrity of the work. To that end, I typically buy my glass materials from marine suppliers, most of whom offer very high quality resins tapes, glass, and tools. For me, it's very much a case of getting what you pay for. Personally, I have had terrible luck with the cheap repair kits that are available at most of the box home improvement stores or chain auto suppliers.


Preform Resources
Dave Craddock
Redford,Michigan
(358 posts)

Registered:
12/20/2008 05:46PM

Main British Car:
72 MGB V6 3.4

Re: Fiberglass
Posted by: Preform Resources
Date: February 19, 2012 06:56PM

Like David says, you must prep the surface, use a heavy grit disc in the area you will be working with and don't touch it with your bare hands, if your going to use a filler use a Duraglass type product( has fiberglass strands in it)If you need to actually laminate
use a good quality Iso poly resin and we use mat for reinforcement,,, why mat you may ask?,,, well I've seen a lot of repairs
where the cloth could be peeled right back out of the repair, using mat( roughly torn ,not sheared) is like a million little fingers
adherring to the surface with no constant edge, ideally you could use epoxy which next to urethane adhesives has the best
adhesion. The remaining potential problem is that after you let it cure ,sand and primer, you should give it some time to fully shrink, in a couple weeks(at room temp) go back and block and reprime that should cut down on any printhru.


DC Townsend
David Townsend
Vermont
(406 posts)

Registered:
11/21/2007 12:22PM

Main British Car:
'78 B (almost done) 30-over SBF, dry sump

authors avatar
Re: Fiberglass
Posted by: DC Townsend
Date: February 19, 2012 07:23PM

David,

Great point on leaving things to fully cure. I'd forgotten to include that. Giving each thing you do time to fully "gas out" is critical. I let each step fully cure before going on to the next with about a week or so between steps (this was during the summer so you need to adjust your cure times to the ambient temps).

I can see value in your use if torn mat rather than cloth but I've had great success using marine glass "tape". It comes in a variety of meshes (I use the coarsest one) and sure makes the job of blending in the panels a bunch easier - not unlike taping wall board joints.

Regards,


pspeaks
Paul Speaks
Dallas, Texas
(698 posts)

Registered:
07/20/2009 06:40PM

Main British Car:
1972 MGB-GT 1979 Ford 302

authors avatar
Re: Fiberglass
Posted by: pspeaks
Date: February 19, 2012 08:54PM

Thanks guys, I built 22 T-Bucket bodies when we had the business but the only place we used metal was encapsulating the door hinge plates inside the door. Our molds were made by a yacht manufacturing company in Florida so we had access to some pretty high grade stuff. We made our own filler with resin, aircil, and chopped glass, but I have a quart of Duraglass in the garage still if itís not too old.

Paul


classic conversions
bill guzman

(294 posts)

Registered:
01/09/2008 01:58AM

Main British Car:


Re: Fiberglass
Posted by: classic conversions
Date: February 23, 2012 01:32PM

I do not know much about glassing. I was told when I installed the flares from Huffaker to drill 1/8 holes along where the flare would be attached to the steel fender, sand with 40 grit paper. Use long strand glass, the long strand glass goes through the holes acting as if they were screws. Then use the glass cloth on the seem of the flare and finish with short strand glass.

I am not sure if it s the right way, but flares have been on the car since 1982 thus far no cracks or moisture issues.
DSC04394.jpg


Preform Resources
Dave Craddock
Redford,Michigan
(358 posts)

Registered:
12/20/2008 05:46PM

Main British Car:
72 MGB V6 3.4

Re: Fiberglass
Posted by: Preform Resources
Date: February 23, 2012 07:58PM

Bill, you created chemical rivets ,so to speak, mainly roughing up the surface and providing a large
bearing area for adhesion, you avoid the cte problems of the substrates.i f yours lasted since 82,
I'd say that was mute testimony as to how it all worked !
Dave



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