Paint: Primer

[Lamar]

In doing a strip and repaint on my 57 Transtar 1/2 ton I have discovered that some of the body panels are primed under the original paint and others are just bare metal no primer at all. Was this a common practice and does anyone know a reason for doing it this way? Also it appears that different types of paint were used on the panels, same color just different paint. Thanks, Lamar

[52 Ragtop]

Paint will not stick (very well) to bare metal, hard to say after all these years. But, after you strip the paint, and do your metal repairs, I would recommend a coat of etching primer, as it will etch into the metal, use it only on bare metal. then a good coat of a high build epoxy primer (2 part) then block and re prime as needed.

I would thaink that the bodies were all painted at the same time, ie: doors, trunk and body shell, the fenders and hood "may" have been painted in a different operation. There were really not many metallic paints back then.
To answer your question, I really doubt that Studebaker did not use a primer under the paint! especially different colors, that would not be economical to change spray guns in the middle!

I would think that over time, panels have been changed and not properly prepped for paint.

Jim

[Skip Lackie]

Unless you have owned your truck since it was new, it is certainly possible that some body panels were replaced or repaired in the past, but were not prepped with primer and/or painted with the same formulation as Studebaker used. Since you are stripping the truck to bare metal, you have the opportunity to take advantage of the better paints available today -- and the excellent advice you'll get here.

[swvalcon]

Once you get it to bare metal and sanded good and clean put a coat of epoxy primer on it. I use Spi. black epoxy but any good brand name will work. When dry you can scuff sand it and do bodywork right over it. Better than going over bare metal and metal wont rust if it gets wet. Etch prime will work but it's 70-80 tech and almost all shops now use epoxy.

[Studebakercenteroforegon]

Years ago a friend of mine bought a '63 Cruiser from a fellow who had worked at the Studebaker Portland Zone Office. There was a bunch of interesting paperwork that he got with the car. One related to Champ pickups and probably applied to earlier Transtars also. It was titled as "confidential" bulletin and read something like..."We have been receiving warranty claims for lack of primer on Champ pickups. For your confidential information the cab is bonderized and then top coated without primer paint. The only Champ body parts that are primed are the doors, hood and front fenders. Thus warranty claims will not be accepted for lack of primer."

[SN-60]

Years ago a friend of mine bought a '63 Cruiser from a fellow who had worked at the Studebaker Portland Zone Office. There was a bunch of interesting paperwork that he got with the car. One related to Champ pickups and probably applied to earlier Transtars also. It was titled as "confidential" bulletin and read something like..."We have been receiving warranty claims for lack of primer on Champ pickups. For your confidential information the cab is bonderized and then top coated without primer paint. The only Champ body parts that are primed are the doors, hood and front fenders. Thus warranty claims will not be accepted for lack of primer."

WOW....That sure sounds like a big factory 'boo-boo' to me!

[Studebakercenteroforegon]

Yes, I was a little surprised myself when I read that confidential bulletin, probably in 1970 or so. But we need to remind ourselves these trucks were intended for a service life of a few years, at which time you returned to your Studebaker dealer and bought a new one. They weren't concerning themselves with what Studebaker lovers were thinking 50 years or so in the future.

[swvalcon]

Thats another way of saying we are saving money by not putting on primer and if the paint falls off it's your problem.

[SN-60]

Yes, I was a little surprised myself when I read that confidential bulletin, probably in 1970 or so. But we need to remind ourselves these trucks were intended for a service life of a few years, at which time you returned to your Studebaker dealer and bought a new one. They weren't concerning themselves with what Studebaker lovers were thinking 50 years or so in the future.

Come to think of it, I wonder what 'BONDERIZED' really means?.....The body was slathered in body filler

[Studebakercenteroforegon]

Bonderizing is a phosphoric acid wash treatment just like bodymen use on bare steel before painting. I believe it converts ferrous oxide to iron phosphate.

[jnormanh]

Come to think of it, I wonder what 'BONDERIZED' really means?.....The body was slathered in body filler

Bonderizing was a trademark of Park Chemical for zinc phosphate coating. It was, and still is, used on many, if not most, steel sheet metal products prior to paint.

IF the zinc phosphate is done correctly, and the paint used is good quality and thick enough, it will perform as well as prime/paint, however a single coat of color over phosphate isn't as thick, and will not last as long as two coats, one prime/one color.

One reason car mfrs liked to use primer is that it provided a light colored, non-reflective surface so that defects could be more easily seen and touched up prior to color. Today's quality control produces sheet metal bodies which don't need that intermediate inspection.

Nowdays most (maybe all) car mfrs use a thin phosphate followed by immersion electrocoat primer and then color. Electrocoat gets into all those enclosed surfaces where sprayed material can never reach. That's one reason modern cars rust less even with thinner sheet metal.

[Lamar]

None of the unprimed panels are replacement parts, the truck had no major body work done when I got it. Sounds like the post about the lack of primer answers the question. The paint on the unprimed panels was well bonded to the metal and in good shape as was the metal. I was just curious as to it being a common thing at Studebaker and sounds like it was at least in some instances. It is getting a coat of epoxy primer on the stripped metal and will get painted with single stage AU in the factory blue color. Will be a daily driver type truck again when finished. Thanks for the info. Lamar

[jclary]

Bonderizing was a trademark of Park Chemical for zinc phosphate coating. It was, and still is, used on many, if not most, steel sheet metal products prior to paint.

IF the zinc phosphate is done correctly, and the paint used is good quality and thick enough, it will perform as well as prime/paint, however a single coat of color over phosphate isn't as thick, and will not last as long as two coats, one prime/one color.

One reason car mfrs liked to use primer is that it provided a light colored, non-reflective surface so that defects could be more easily seen and touched up prior to color. Today's quality control produces sheet metal bodies which don't need that intermediate inspection.

Nowdays most (maybe all) car mfrs use a thin phosphate followed by immersion electrocoat primer and then color. Electrocoat gets into all those enclosed surfaces where sprayed material can never reach. That's one reason modern cars rust less even with thinner sheet metal.

Good info here. For my "backyard" paint jobs, I always use a phosphate wash as a final prep before painting. However, a coat of PPG DP epoxy primer always preceded any top coat paint.

[Hallabutt]

Lamar,

Sounds like a great truck to start with and a good candidate for a scuff and shoot. Why did you go through the extra work of stripping and the paint build process? I'm just trying to understand why you chose that route, not trying to pick on you.

[Lamar]

I don't mind the questions. The truck was a farm truck all it's life before I got it and had a lot of relatively minor dents, scrapes and such so the owners son in law did a quick and dirty bondo patch and paint a year or so before I acquired it. I have driven it for several years and just decided to do a better job of repairing it. I am stripping the paint and removing all the bondo so I can repair the damage correctly and repaint it. Also had some minor rust in the usual places that are being replaced/repaired also. Lamar