The Stovebolt Site Forums The Shop Area General Truck Talk Factory Primer: Red Oxide and Black

Anybody work at a GM assy plant circa 60's/70's?

Have you noticed that the factory seems to have painted the hood and dog house with black primer, and the rest of our trucks with red oxide?

I am kind of fixated on patina here lately.... and this seems to be a reoccuring observance of mine.

Do we have anybody on this site that actually worked at a GM truck assembly plant back in the 60's and early 70's?

Maybe these photos will get you guys scratchin your heads too!

http://67-72chevytrucks.com/vboard/showthread.php?t=427282

no puzzle, the black is EDP [electro deposit primer], added when the parts were stamped [service replacement parts come that way], the brown is spray primer, done after the cab/box sub-assemblies were together

Bill

So you are saying they didn't spray red oxide on the hood and dog house?

why would they spray primer on already primed parts? EDP is actually a better primer than red oxide - and in the 60's it may still have been red lead

Bill

I’ve seen this same treatment in the Advance Design trucks also, that is, red oxide primer on the cabs.
And Bill, isn’t red lead (trilead teroxide) the same thing as red oxide primer? It was the pigment in red oxide primer. It is little used today as a rust preventative primer. It was also widely used on structural steel in the building industry and in electric motors, (not the same as Glyptal which does not contain red lead).

Denny Graham
Sandwich, IL

yes, red lead [teTroxide] primer was called red oxide, but since lead paints got trashed, the modern red oxide replacement contains no lead, it's some synthetic/oil base - I remember folks complaining way back that it didn't work as well as the "good ol stuff", but I believe it's still common in primers for marine environments, ships and bridgework iron/steel

had to go look up the switch - lead was banned on "consumer goods" in '77, so auto paints/primers before than could have contained lead, so take proper care sanding the brown primers on these ol trucks, even if it's not factory paint!

Bill

EDP in the 60s is a possibility (and is the time period in HRJ's start to this thread), but this discussion had moved into the 40s & 50s (A-D years). Red-oxide (leaded) paints was of course available prior to the 60s but EDP supposedly was not used until after the A-D years.

As Denny posted in another recent message about the black paint/primer used on A-D trucks, it is hard as heck to remove it, but it is not very good at rust prevention (especially if scratched).

I stand corrected Tim, the first application EDP in automotive use was in the early 60's, I believe Ford was the first to use it. I recall a discussion we had about this a year or two back.
In stripping some of the interior parts for the '54 I've run into a black primer under the Pearl Beige that looks exactly like the EDP parts. I started working for Chevrolet in 1959 as a parts runner and our entire attic above the dealership was stocked with black primed sheet metal parts hanging like beef in a meat locker, much of which had been there for a decade or more. I do recall at the body shops that I delivered to seeing them scuff the black primer and shoot primer surfacer over it before finishing. That’s the primer that I'm seeing under the paint. This early pre 60's black primer also is tough to cut. Just today I've had some parts soaking in Aircraft stripper for more than an hour and all it does is slightly soften the finish or the primer. This stripper will take the hide right of you if you splash it on your bare skin.
We still haven’t heard from any of our resident paint engineers or chemists concerning exactly what this paint was. The lead was a pigment but it’s the binder that is hard to cut and I would imagine it was some sort of oil base. Lots of guesses but you know how reliable guesses are. I’m sure this is a leaded paint because when I wire brush it on the pedestal grinder it has that distinctive sweet smell to it. I want to remove the majority of it chemically because I hate to cover my entire shop with the residue from wire brushing it or using a 3m stripping disc for the task.
Denny Graham
Sandwich, IL

Denny - suprisingly, it looks like it's epoxy ester primer, epoxy being pretty tough of course .... and electro-deposition was invented/discovered in the 30's - Dupont says you're right, Ford started common automotive use in '63, but these e-coat technology suppliers claim some form of it was being used in the 50's .... interesting stuff, especially that first link

Bill

I find it very interesting where they say that GM continued to use nitrocellulose lacquer until the mid 60’s. Believe me, this interior paint in the ’54 taint any form of lacquer. This stripper will lift any lacquer.
Denny Graham
Sandwich, IL