1957 paint process question

[Rod K.]

A restorer of mostly '58-'62 Corvettes says the paint was buffed AFTER much of the exterior trim was installed, resulting in what he called a "haze" line next to the trim piece where the paint wasn't buffed, something the judges look for.

However, a photo at the top right of pg 145 in Noland Adams' Restoration Guide (1956-57 section) shows workers buffing bare bodies with no trim installed, possibly just out of the drying ovens. Many of the pictures in this section of Adams' book were taken in July 1957, although this particular one is not so identified. I couldn't find a similar photo in the later 58-62 sections.

Can someone confirm that buffing the unassembled body was the practice in 1957? Was it later changed? It seems to me it would be much more efficient to do that work prior to installing anything that would require masking or avoidance.

Thanks for your input.

[John H.]

Re: 1957 paint process question

A restorer of mostly '58-'62 Corvettes says the paint was buffed AFTER much of the exterior trim was installed, resulting in what he called a "haze" line next to the trim piece where the paint wasn't buffed, something the judges look for.

However, a photo at the top right of pg 145 in Noland Adams' Restoration Guide (1956-57 section) shows workers buffing bare bodies with no trim installed, possibly just out of the drying ovens. Many of the pictures in this section of Adams' book were taken in July 1957, although this particular one is not so identified. I couldn't find a similar photo in the later 58-62 sections.

Can someone confirm that buffing the unassembled body was the practice in 1957? Was it later changed? It seems to me it would be much more efficient to do that work prior to installing anything that would require masking or avoidance.

Thanks for your input.

Rod -

The last process in the Paint Shop was buffing, before any of the trim and hardware was installed. After the car came off the line and went through roll test, water test, final paint repair, and final trim line interior installation, it was buffed again as a completed car before it was shipped.

[Rod K.]

Re: 1957 paint process question

Thank you, John. Did this process continue throughout the C1 era?

[John D.]

Re: 1957 paint process question

John

Did the C1's go through reflow ovens in the paint shop ?

[John H.]

Re: 1957 paint process question

Thank you, John. Did this process continue throughout the C1 era?

Rod -

Yes, it did.

[John H.]

Re: 1957 paint process question

John

Did the C1's go through reflow ovens in the paint shop ?

John -

The final bake oven at Corvette is sometimes referred to as a "reflow oven", but it wasn't. The GM "Magic-Mirror" acrylic lacquer (sourced exclusively from DuPont) reflowed in the steel body passenger car plants at 325*F-350*F, but the Corvette fiberglass body couldn't stand that temperature. The gas-fired final bake oven in the main Paint Shop at Corvette was 45 minutes at 250*F, which cured the paint, but it only partially reflowed; that's why the body had to be buffed to bring up the final gloss (which wasn't necessary in the steel body plants). The lacquer paint used in Final Paint Repair (on the finished car) was a different formulation, as it had to cure at 160*F in an infra-red oven.

[Steven B.]

Re: 1957 paint process question

John -

The final bake oven at Corvette is sometimes referred to as a "reflow oven", but it wasn't. The GM "Magic-Mirror" acrylic lacquer (sourced exclusively from DuPont) reflowed in the steel body passenger car plants at 325*F-350*F, but the Corvette fiberglass body couldn't stand that temperature. The gas-fired final bake oven in the main Paint Shop at Corvette was 45 minutes at 250*F, which cured the paint, but it only partially reflowed; that's why the body had to be buffed to bring up the final gloss (which wasn't necessary in the steel body plants). The lacquer paint used in Final Paint Repair (on the finished car) was a different formulation, as it had to cure at 160*F in an infra-red oven.

John, was it the same with nitrocellulose?

Thanks,

Steve

[John H.]

Re: 1957 paint process question

John, was it the same with nitrocellulose?

Thanks,

Steve

Steve -

Yes, it was - there were no Paint Shop facility or process changes associated with the change from nitrocellulose to acrylic lacquer; the medieval nature of the Paint Shop didn't change at all until the late 70's, and then only slightly.

[Michael H.]

Re: 1957 paint process question

John -

The final bake oven at Corvette is sometimes referred to as a "reflow oven", but it wasn't. The GM "Magic-Mirror" acrylic lacquer (sourced exclusively from DuPont) reflowed in the steel body passenger car plants at 325*F-350*F, but the Corvette fiberglass body couldn't stand that temperature. The gas-fired final bake oven in the main Paint Shop at Corvette was 45 minutes at 250*F, which cured the paint, but it only partially reflowed; that's why the body had to be buffed to bring up the final gloss (which wasn't necessary in the steel body plants). The lacquer paint used in Final Paint Repair (on the finished car) was a different formulation, as it had to cure at 160*F in an infra-red oven.

John,

I'm not sure if/when the process changed for C2 or C3 but at some point, I don't think any of the body was first buffed when it came out of the reflow oven before hard trim. I only remember the process after most body trim was installed.

The reflow oven at Corvette actually did change the appearance of the body paint quite a bit, at least in the 70's and 80's. The paint looked so good it almost didn't need polishing.
The only part of the body paint that was buffed, at all, was the horizontal surfaces (hood/deck) and the upper half of most side panels.

I think most folks think the entire body was carefully buffed, including hand rubbing in areas that couldn't be machine polished. That's absolutely not the case.
The buffing/polishing operation only lasted a few minutes.

[Steven B.]

Re: 1957 paint process question

'saw a new '63 saddle tan/tan coupe come into local dealer. My next door neighbor did undercoating and some new car prep there. One day I walked in to see him buffing the paint as there was little shine. He mostly did the horizontal panels and not much of the vertical panels, like the factory. A few months later a silver blue/blue 2 top car came in and didn't need buffing---or at least it did not get buffed. That paint job was pretty good.

Steve

[John H.]

Re: 1957 paint process question

John,

I'm not sure if/when the process changed for C2 or C3 but at some point, I don't think any of the body was first buffed when it came out of the reflow oven before hard trim. I only remember the process after most body trim was installed.

Michael -

That probably took place later during the C3 era, when SMC had replaced polyester fiberglass, polane and in-mold primers were introduced at the panel molders, and polane primer was introduced at St. Louis, which reduced surface prep requirements somewhat and improved raw panel surface finish. When I left there in '68 they were still buffing at the end of the Paint Shop prior to loading the body on the Hard Trim Line, and I never went back as I moved on to other assignments.