Paint issue
03-15-2018, 05:02 PM
#1
Paint issue
2005 Z51 Paint bubbling at rear edge of hatch/decklid. Have had it re-painted twice. Body shop says problem resulting from glue lamination leaching out from fiberglass layers. GM won't give assurance that replacement hatch/decklid won't have same problem. Has this been experienced by any other C6 owner?
03-15-2018, 05:40 PM
#2
2005 Z51 Paint bubbling at rear edge of hatch/decklid. Have had it re-painted twice. Body shop says problem resulting from glue lamination leaching out from fiberglass layers. GM won't give assurance that replacement hatch/decklid won't have same problem. Has this been experienced by any other C6 owner?
And no, there is not layers to the body panels (they are not fiberglass), and each panel is just produced from a single layer of SMC that is heat compression molded.
So watch this, and if the spots that are bubbling off the rear fender cover are at the bolt holes for a Zr1 spoiler, then the problem is when the spoiler was removed and the drill holes repaired, SMC filler was not used to repair the holes post paint isntead.
If the problem is longer strips of the paint bubbling, then instead of bolts used to install the spoiler, double stick tape or silicone was used instead, and it was not correctly removed before the rear was resprayed to begin with.
To add, when the vet is sprayed, it's a two part process. Hence base coat, then tinted clear coat. So if the vet did not have a spoiler/spoiler repair that is causing the problems, then the problem is the shop did not prep or use the correct paint/sealer, and why their paint is bubbling off instead.
Last edited by Dano523; 03-15-2018 at 05:46 PM.
03-15-2018, 06:53 PM
#4
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St. Jude Donor '15
"In honor of jpee"
Repainted twice, hmmm. Question: is this a shop that knows Corvettes, not that "fiberglass" and SMC are that exotic, but it definitely is different from aluminum, steel, etc. Another question: is the bumper cap hitting the edge at all in any way?
Anyway, here's some stuff you might like to read on the body of Corvettes. SMC has been on Corvettes since '73 and fiberglass in the layering has been gone for awhile.
"...Starting with the third generation in 1968, the body parts were manufactured with a press mold process, whereby the fiberglass material and resin were shaped in a die-like tool that produced smoother parts more quickly. It was a significant advancement in forming technology and laid the groundwork for a change in the body panels’ material in 1973. That year, the composition changed from conventional fiberglass to sheet-molded composite, or SMC, which was composed of fiberglass, resin and a catalyst formed under high heat and pressure. The ratio of resin to fiberglass was reduced with SMC, while the fiberglass itself was a bit coarser. The new material helped produce panels that were smoother right out of the mold, resulting in higher-quality paint finishes.
All Corvettes since 1973 have used SMC body panels, but the material composition has changed dramatically, featuring less traditional fiberglass and more lightweight plastic. The early SMC material created parts that were stronger and more rigid, but more brittle. As SMC technology and production experience evolved, Corvette engineers were able to alter the material composition and the body parts’ specifications to trim the Corvette’s curb weight. Mostly, that happened through making thinner body panels, because SMC was denser and stronger than conventional fiberglass.
It’s rare that a next-generation model of any vehicle is lighter than its predecessor, but that was the case with the fifth-generation (C5) Corvette in 1997. In fact, the 1997 Corvette was larger overall – longer and wider – than the 1996 model, but it weighed nearly 100 pounds less. A greater emphasis on advanced materials was the reason.
The contributors that helped drive down the C5’s curb weight included the use of SMC body panels with more plastic than ever before. The material, basically the same used in the current sixth-generation (C6) Corvette, was composed of about 40 percent resin – polyester, vinyl ester, styrene or a blend of all three – 33 percent calcium-carbonate filler, 20 percent chopped fiberglass, The remaining 7 percent is resin and hardeners that improve the out-of-mold surface finish."
from here: http://media.gm.com/media/us/en/gm/h..._corvette.html
Anyway, here's some stuff you might like to read on the body of Corvettes. SMC has been on Corvettes since '73 and fiberglass in the layering has been gone for awhile.
"...Starting with the third generation in 1968, the body parts were manufactured with a press mold process, whereby the fiberglass material and resin were shaped in a die-like tool that produced smoother parts more quickly. It was a significant advancement in forming technology and laid the groundwork for a change in the body panels’ material in 1973. That year, the composition changed from conventional fiberglass to sheet-molded composite, or SMC, which was composed of fiberglass, resin and a catalyst formed under high heat and pressure. The ratio of resin to fiberglass was reduced with SMC, while the fiberglass itself was a bit coarser. The new material helped produce panels that were smoother right out of the mold, resulting in higher-quality paint finishes.
All Corvettes since 1973 have used SMC body panels, but the material composition has changed dramatically, featuring less traditional fiberglass and more lightweight plastic. The early SMC material created parts that were stronger and more rigid, but more brittle. As SMC technology and production experience evolved, Corvette engineers were able to alter the material composition and the body parts’ specifications to trim the Corvette’s curb weight. Mostly, that happened through making thinner body panels, because SMC was denser and stronger than conventional fiberglass.
It’s rare that a next-generation model of any vehicle is lighter than its predecessor, but that was the case with the fifth-generation (C5) Corvette in 1997. In fact, the 1997 Corvette was larger overall – longer and wider – than the 1996 model, but it weighed nearly 100 pounds less. A greater emphasis on advanced materials was the reason.
The contributors that helped drive down the C5’s curb weight included the use of SMC body panels with more plastic than ever before. The material, basically the same used in the current sixth-generation (C6) Corvette, was composed of about 40 percent resin – polyester, vinyl ester, styrene or a blend of all three – 33 percent calcium-carbonate filler, 20 percent chopped fiberglass, The remaining 7 percent is resin and hardeners that improve the out-of-mold surface finish."
from here: http://media.gm.com/media/us/en/gm/h..._corvette.html
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Landru (03-16-2018)
03-19-2018, 03:36 PM
#5
Paint problem
Repainted twice, hmmm. Question: is this a shop that knows Corvettes, not that "fiberglass" and SMC are that exotic, but it definitely is different from aluminum, steel, etc. Another question: is the bumper cap hitting the edge at all in any way?
Anyway, here's some stuff you might like to read on the body of Corvettes. SMC has been on Corvettes since '73 and fiberglass in the layering has been gone for awhile.
"...Starting with the third generation in 1968, the body parts were manufactured with a press mold process, whereby the fiberglass material and resin were shaped in a die-like tool that produced smoother parts more quickly. It was a significant advancement in forming technology and laid the groundwork for a change in the body panels’ material in 1973. That year, the composition changed from conventional fiberglass to sheet-molded composite, or SMC, which was composed of fiberglass, resin and a catalyst formed under high heat and pressure. The ratio of resin to fiberglass was reduced with SMC, while the fiberglass itself was a bit coarser. The new material helped produce panels that were smoother right out of the mold, resulting in higher-quality paint finishes.
All Corvettes since 1973 have used SMC body panels, but the material composition has changed dramatically, featuring less traditional fiberglass and more lightweight plastic. The early SMC material created parts that were stronger and more rigid, but more brittle. As SMC technology and production experience evolved, Corvette engineers were able to alter the material composition and the body parts’ specifications to trim the Corvette’s curb weight. Mostly, that happened through making thinner body panels, because SMC was denser and stronger than conventional fiberglass.
It’s rare that a next-generation model of any vehicle is lighter than its predecessor, but that was the case with the fifth-generation (C5) Corvette in 1997. In fact, the 1997 Corvette was larger overall – longer and wider – than the 1996 model, but it weighed nearly 100 pounds less. A greater emphasis on advanced materials was the reason.
The contributors that helped drive down the C5’s curb weight included the use of SMC body panels with more plastic than ever before. The material, basically the same used in the current sixth-generation (C6) Corvette, was composed of about 40 percent resin – polyester, vinyl ester, styrene or a blend of all three – 33 percent calcium-carbonate filler, 20 percent chopped fiberglass, The remaining 7 percent is resin and hardeners that improve the out-of-mold surface finish."
from here: http://media.gm.com/media/us/en/gm/h..._corvette.html
Anyway, here's some stuff you might like to read on the body of Corvettes. SMC has been on Corvettes since '73 and fiberglass in the layering has been gone for awhile.
"...Starting with the third generation in 1968, the body parts were manufactured with a press mold process, whereby the fiberglass material and resin were shaped in a die-like tool that produced smoother parts more quickly. It was a significant advancement in forming technology and laid the groundwork for a change in the body panels’ material in 1973. That year, the composition changed from conventional fiberglass to sheet-molded composite, or SMC, which was composed of fiberglass, resin and a catalyst formed under high heat and pressure. The ratio of resin to fiberglass was reduced with SMC, while the fiberglass itself was a bit coarser. The new material helped produce panels that were smoother right out of the mold, resulting in higher-quality paint finishes.
All Corvettes since 1973 have used SMC body panels, but the material composition has changed dramatically, featuring less traditional fiberglass and more lightweight plastic. The early SMC material created parts that were stronger and more rigid, but more brittle. As SMC technology and production experience evolved, Corvette engineers were able to alter the material composition and the body parts’ specifications to trim the Corvette’s curb weight. Mostly, that happened through making thinner body panels, because SMC was denser and stronger than conventional fiberglass.
It’s rare that a next-generation model of any vehicle is lighter than its predecessor, but that was the case with the fifth-generation (C5) Corvette in 1997. In fact, the 1997 Corvette was larger overall – longer and wider – than the 1996 model, but it weighed nearly 100 pounds less. A greater emphasis on advanced materials was the reason.
The contributors that helped drive down the C5’s curb weight included the use of SMC body panels with more plastic than ever before. The material, basically the same used in the current sixth-generation (C6) Corvette, was composed of about 40 percent resin – polyester, vinyl ester, styrene or a blend of all three – 33 percent calcium-carbonate filler, 20 percent chopped fiberglass, The remaining 7 percent is resin and hardeners that improve the out-of-mold surface finish."
from here: http://media.gm.com/media/us/en/gm/h..._corvette.html
03-19-2018, 04:21 PM
#6
Drifting
I have a base 2008 convertible and at a cruise in Saturday, I noticed my JSB bubbling up along the driver's side of the deck lid. Looked like water drops but would not dry off, I would take a picture but we are having extreme rain weather. Also, it is original paint as far as I know, I bought it used in 2013.
Last edited by 72GACRZR; 03-19-2018 at 04:26 PM.
03-19-2018, 05:35 PM
#7
I would have sworn that my 77 was still the good ol fashion fiberglass cause it had the infamous seam bleed through in several locations (rear 1/4s)......is this SMC stuff still fiberglass but in some different form ?
03-20-2018, 12:26 AM
#8
SMC (sheet moulding composite) is a polyester (plastic) panel that has strengthen fibers it it.
Here is the low down of when body panels stopped being fiberglass sheets with resin (think surfboard or boats),
And become SMC panels isntead.
https://www.corvetteforum.com/forums...smc-start.html
Last edited by Dano523; 03-20-2018 at 12:29 AM.
03-20-2018, 06:12 AM
#9
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St. Jude Donor '15
"In honor of jpee"
^^^ I agree. And the partial sentence that is key in what I found is, "...the composition changed from conventional fiberglass to sheet-molded composite, or SMC, which was composed of fiberglass, resin and a catalyst formed under high heat and pressure. The ratio of resin to fiberglass was reduced with SMC, while the fiberglass itself was a bit coarser."
Why would the paint bubble on an original car which has never been re-painted? I doubt if it's the paint. So, it has to be something with the material below, the SMC. Maybe a slow release of gas. Or, a reaction (very slow) between the paint formulation over a period of years and the surface below. Truly, only the long-term testing by a car paint company could tell you.
I do know that like Corvettes, paint cos. are constantly changing and improving paint. I remember when my '93 got severe acid rain pockmarking of the clearcoat. I don't see that any longer--doesn't mean it's not happening---I'm just not seeing it, and I do look at cars.
Edit: One more example of, look to the Forum for the answer! I found this on "General Corvette Topics" (which I didn't know even existed!)
See Post #7 especially. I used to know about painting C2s and using "gel coat"--apparently, for some that is a passe method. But Post #7 is interesting. I have seen one example of a beautiful C3 painted by the owner of a Corvette body shop w/o gel coat many years ago--and I saw it later when he told me he had to repaint it because the paint was failing/fiberglass strands poking thru.
End argument is there is controversy over gel coat, epoxy and polyester (the same stuff of pants and shirts--j/k). Ask your paint shop what they are using would be my suggestion.
https://www.corvetteforum.com/forums...le-to-use.html
Why would the paint bubble on an original car which has never been re-painted? I doubt if it's the paint. So, it has to be something with the material below, the SMC. Maybe a slow release of gas. Or, a reaction (very slow) between the paint formulation over a period of years and the surface below. Truly, only the long-term testing by a car paint company could tell you.
I do know that like Corvettes, paint cos. are constantly changing and improving paint. I remember when my '93 got severe acid rain pockmarking of the clearcoat. I don't see that any longer--doesn't mean it's not happening---I'm just not seeing it, and I do look at cars.
Edit: One more example of, look to the Forum for the answer! I found this on "General Corvette Topics" (which I didn't know even existed!)
See Post #7 especially. I used to know about painting C2s and using "gel coat"--apparently, for some that is a passe method. But Post #7 is interesting. I have seen one example of a beautiful C3 painted by the owner of a Corvette body shop w/o gel coat many years ago--and I saw it later when he told me he had to repaint it because the paint was failing/fiberglass strands poking thru.
End argument is there is controversy over gel coat, epoxy and polyester (the same stuff of pants and shirts--j/k). Ask your paint shop what they are using would be my suggestion.
https://www.corvetteforum.com/forums...le-to-use.html
Last edited by AORoads; 03-20-2018 at 06:22 AM.
03-20-2018, 11:09 AM
#10
"gel-coat" on a automotive finish would seem somewhat "interesting" to be sure. Not sure how well gel coat would hold up under the rough ride of a sports car, particularly a Corvette in cold weather. Anyone familiar with boats can attest the small gel cracks that always seem to appear somewhere due to the constant pounding of the water. and thats keeping in mind that most boating is done during warm weather. All this is assuming of course that they haven't come up with some new type of gel that holds up better.
03-20-2018, 09:10 PM
#11
Drifting
Smc is still fiberglass just in a different layup process and a different ratio of glass to resin
Not knowing exactly where you bubbles are I wonder if it is not permeation from the bonding adhesive between the outer panel and the inner panel.
Look at your inner fenders - you can see the glass fibers
Now the bumper, splitter, and spoliers are all ABS plastic
Not knowing exactly where you bubbles are I wonder if it is not permeation from the bonding adhesive between the outer panel and the inner panel.
Look at your inner fenders - you can see the glass fibers
Now the bumper, splitter, and spoliers are all ABS plastic