Just curious if anyone knows.......in the factory paint shop, how many coats of lacquer did the GM painters apply to a typical A body? It was just "X" amounts of lacquer color and no clear at all....correct! I would assume that the amount would have to be obtained from either factory engineers, painters or assembly documents. I was just thinking after seeing the video of the Arlington, Texas assembly plant.

OLE442

 

BC/CC paint was never used as factory paint on A bodies in the 60s and 70s. I'm not sure how many coats were sprayed.

 

You are correct about no BC/CC, but clear over lacquer was not uncommon for custom paint. Factories did not use clear typically. Lacquer typically requires 2-3 coats for proper coverage, depending on color and metallic or not.

 

Yup, that's why I only said lacquer. From my experience, I would say Joe's comment sounds right about the 2 to 3 coats. Back in the day, original painted GM cars did not have a lot of color thickness when you sanded them down.
I figured I'd do three coats of lacquer on my car and then three coats of high performance clear and then wet sand and buff mine. I doubt that GM ever sanded and buffed normal production cars.

OLE442

 

You pretty much always have to color sand and buff lacquer. Clear will provide more gloss than OEM. If you are trying to faithfully replicate the factory finish, don't use clear.

 

GM as well as others back in the day used a process called dispurtion(Spelling?) lacquer. The car was conveyed through a series of robot sprayers. All done in ONE process that provided the required millage. It was not a multi coat process. No clears or buffing etc. Bodies had doors and trunk lids installed. Fenders and hoods were painted separately adjacent to the body line. It was not uncommon for the fenders and hoods to be off color match to the body. Paint came into the factory in drums/vats. As the assembly line was painting a particular color the metallics/colors would be off after painting 100's of cars from metallic settling poor agitation etc. This variation still happens today and the paint industry calls it "VARIANTS" There could be multiple paint formulas for the same color due to this fact.

 

Yes. In the industry we always say “there’s no such thing as a perfect color match”. In modern factories paint can be pumped through miles of pipe before it reaches its destination for application. They’ve even determined that this erodes the metallics to the point that they can have a different affect. Some colors have over a dozen variants for the same color code.

 

Paint is measured by mil thickness, not number of coats. The application processes at the factory are so much different than that of the aftermarket that it can’t be compared by the number of “coats”. Different painters can achieve the same mil thickness with different numbers of coats. As a pro painter, I may be able to achieve in two coats what takes you 4.

Technically, the answer to your question is one. The factory applied one coat. You would probably need 2-3 to achieve the same mil build though.

 

Yes, what ijasond said, you cannot compare factory paint application to "aftermarket". A guy I know visited my shop and was surprised I could paint cars, without the fancy equipment, and a baking booth. He worked at one of the OEM factories.
I learned how to paint, by a locally famous custom painter. Lacquer. Lacquer is thinned by 100% or more. You need to put on many coats to get good coverage, depending on the color, of course, The metallics were more translucent and needed more coats than solid colors. We used to put on 6-8 coats, wait a day or 2, block out with 600 and do another 6-8. You probably remove 3-4 when sanding and buffing ( at least in the old days, we only had 600 as the finest grit. You had to sand between paint sessions (NOT single coats, like the urban myth), because the lacquers would swell the lacquer primer coats ( and red lead), and then shrink back down, causing imperfections. Sanding between multi-coats was a way to eliminate that problem and be sure of a smooth finish.
As for clear, it was a common thing for custom paint. Dupont clear, though, was very yellow-y, not used. IIRC, R-M was crystal clear, and the choice of custom painters. 2 problems with using clear of lacquer jobs. One is the yellowing that a lot of brands had, the other was the excess paint build up might cause cracking, spiderwebbing, down the road.
Lacquer clear did not have the issues that BC/CC had in the past, because lacquer actually melts and becomes one film, with the color paint under it. Unlike the modern paints that have 2 different chemistries between base and clear, and can delaminate.

 

This is a very enjoyable video of Fisher Body in 1970. From design and engineering through sending the completed and trimmed body/front-end clip on to the automotive assembly plant, Painting starts at about 20:30. Mostly Monte carlo and some Chevelle.

 

All the young guys think base/clear is the best paint and I’ll argue that it’s not every time. There are two types of adhesion: 1) mechanical(usually achieved by sanding, but can also be done by blasting or etching as well) 2) chemical.

The bond of clearcoat to the base is not a true chemical or mechanical adhesion and therefor sooner or later it can and will delaminate. If you have good chemical or mechanical adhesion, delamination is not possible.

Base/clear is as close to idiot proof as automotive paint has ever been. That’s why it’s popular and has become the industry standard. Try telling these young painters that though. They think single stage is junk because it’s more difficult and often lies outside of their skillset/comfort zone. I’ll take single stage urethane over basecoat all day long and twice on Sunday. The only time I use base/clear on my personal stuff is metallic colors that I want to cut and buff. To me that’s the only advantage of base/clear vs single stage.