OEM fiberglass

[Blair K.]

Hello - Can someone school me on grey fiberglass??? - what year C3s' used this??? Thanks in advance.

[Wayne W.]

Re: OEM fiberglass

Its a little more complicated that that. You know the thing about shades of gray. They even cant decide how to spell it, gray or grey. And then you have a change of fiberglass types during the time period, so what do you want to know.

[Dick W.]

Re: OEM fiberglass

Its a little more complicated that that. You know the thing about shades of gray. They even cant decide how to spell it, gray or grey. And then you have a change of fiberglass types during the time period, so what do you want to know.

Maybe 50 Shades of Gray?

[Patrick B.]

Re: OEM fiberglass

Blair: When I stripped a late 69 convertible built July 69, it was all dark gray (grey?) glass that looked the same as a 67. When I stripped a late 70 coupe built July 70, it had white doors but the rest was dark gray like the 69. The dark gray glass (which looks almost black as an NOS panel before it is sanded) is made with polyester resin. The white glass I believe is called SMC (sheet molded compound) and is made with epoxy resin. I think by 1975 all the panels of a C3 were white SMC but I don't know when they were phased in. What year car are you concerned about?

[Paul O.]

Re: OEM fiberglass

Here are a few photos to show the difference. The first are the dark or polyester fiberglass second are SMC fiberglass. All are over the counter service parts.

[Alan S.]

Re: OEM fiberglass

Hi,
Here are some pictures showing the different "shades of gray" on 71 #6589, built mid-January.
I believe it shows the combination of the 2 materials Patrick describes.
Notice the difference in the color of the bond material.
Regards,
Alan

[Michael D.]

Re: OEM fiberglass

...Maybe 50 Shades of Gray? ...

That's sharp.

[Alan S.]

Re: OEM fiberglass

Hi,
"Maybe 50 Shades of Gray?"
I thought it was a rather restrained comment!
Regards,
Alan

[Blair K.]

Re: OEM fiberglass

What year car are you concerned about?[/QUOTE]

'68 - '69 and '70 - '72 Thanks

[Patrick B.]

Re: OEM fiberglass

Hi,
Here are some pictures showing the different "shades of gray" on 71 #6589, built mid-January.
I believe it shows the combination of the 2 materials Patrick describes.
Notice the difference in the color of the bond material.
Regards,
Alan

Allen: I'm surprised how much SMC was in use less than 6 months after my 70 was built. Except for the doors, all of the 70 body was the same material as your front surround. A complete SMC car must have been out before 1975 for sure.

By the way, repair and bonding materials for SMC panels must be based on epoxy resin. The polyester materials that work well on the gray panels are not recommended. However, the epoxy materials will work on the polyester panels.

[Wayne W.]

Re: OEM fiberglass

OK, Here are the general observations.

68- All Polyester resin fiberglass, generally darker gray, black.
69- All polyester early with various shades of gray, black. Later 69 some doors made of a product of General Tire called Gennite. This product was similar to SMC and was a light gray.
70 - More Gennite panels used in different locations, more light gray panels used.
71 - A continuation of the trend to Gennite. The first SMC panels used, on late rear quarters. SMC panels had a marble effect and a light gray color.
72- More use of SMC for other panels, still a mixture of polyester, gennite, and SMC.
73- The trend to mostly SMC continues. The rear deck was the last polyester panel still to survive.
74 - With the change to the rubber rear bumper, the rear deck was redesigned, and the last vestige of polyester was gone. Even with all SMC there was varying shades of gray.
75- 82 All panels were the marble gray SMC. Still with varying shades of gray.

[Blair K.]

Re: OEM fiberglass

OK, Here are the general observations.

68- All Polyester resin fiberglass, generally darker gray, black.
69- All polyester early with various shades of gray, black. Later 69 some doors made of a product of General Tire called Gennite. This product was similar to SMC and was a light gray.
70 - More Gennite panels used in different locations, more light gray panels used.
71 - A continuation of the trend to Gennite. The first SMC panels used, on late rear quarters. SMC panels had a marble effect and a light gray color.
72- More use of SMC for other panels, still a mixture of polyester, gennite, and SMC.
73- The trend to mostly SMC continues. The rear deck was the last polyester panel still to survive.
74 - With the change to the rubber rear bumper, the rear deck was redesigned, and the last vestige of polyester was gone. Even with all SMC there was varying shades of gray.
75- 82 All panels were the marble gray SMC. Still with varying shades of gray.

Perfect - Thank-you, Wayne for your time and reply. Much appreciated