Author Topic: Stainless Trim isn't truly just stainless -- or is it?  (Read 835 times)

Offline Bossbill

  • Hero Member
  • *****
  • Posts: 3279
  • In the middle of project hell
Stainless Trim isn't truly just stainless -- or is it?
« on: February 04, 2020, 08:04:33 PM »
I've noticed a few things about Ford "polished" stainless steel (s/s). It doesn't appear to be just s/s as the color of the polished item is not the same as a new unpolished piece.

A friend with a restoration shop has another local shop polish his s/s. When it comes back it looks really nice, but has a very slight yellow tinge to it.

I tried to polish a spare T-Bird (aka Shelby) s/s wheel cover. After a test polish the area nearest the outer edge actually has a brass line going all the way around the circumference. It wasn't there before. This may be either a tooling mark or some kind of braze line. So somehow I polished off "some top surface."
In other words, various pieces of trim on the car appear to have some finish on top of the stainless.

I read in the Corvette forum (heh, they do some really nice restoration work) about how Corvette s/s is stainless with a flash or smack chrome on top of it.
This makes sense as all of the s/s and chrome on the car should have the same looking finish.

Here is a forum snippet about this process back then. It might be assumed that the big three emulated each other with respect to these processes.


"We're talking about the original GM process, not the triple (copper-nickel-chrome) "show-chrome" process used by outside/aftermarket platers. GM didn't use copper as a plating base (except for some Cadillac applications) - GM "factory chrome" was nickel on a bare steel base, then (clear) chrome .0002"-.0004" (that's ten-thousandths, not thousandths) thick to protect the nickel from oxidation. A good friend of mine was the Production Manager at Chevrolet-Livonia Spring & Bumper, where ALL Chevrolet bumpers were made, and I witnessed that entire process several times in the late 60's.

GM factory stainless exterior (and most interior) bright polished trim moldings were "flash-chromed" (also called "smack-chromed") after stamping and polishing to protect the stainless substrate from oxidation/dulling. Most of these parts were made by Fisher Body or by Ternstedt Division, and every Fisher and Ternstedt plant had its own chrome plating line for flash-chroming stainless parts; I witnessed several of those Fisher Body flash-chrome plating processes too (specifically on windshield and backlite reveal moldings).

Don't confuse aftermarket/restoration plating practices with the original GM factory plating processes - they're different."

Another very knowledgeable NCRS "stainless guy" posted the following:
"Think of the flash chrome as nothing more than a really really hard layer of clear over the nickel or stainless. Because stainless has enough nickel content, it was never nickel plated, just polished and smacked chrome plated. This plating is less than .0002 thick, You can buff through it with aggressive polish, but it is easier to chemically strip."
« Last Edit: February 04, 2020, 08:20:49 PM by Bossbill »
Bill
Concours  Actual Ford Build 3/2/67 GT350 01375
Driven      6/6/70 0T02G160xxx Boss 302
Modified   5/18/65 5F09A728xxx Boss 347 Terminator-X 8-Stack
Race        65 2+2 Coupe conversion

Offline Bob Gaines

  • Global Moderator
  • Hero Member
  • ****
  • Posts: 9317
Re: Stainless Trim isn't truly just stainless -- or is it?
« Reply #1 on: February 04, 2020, 08:21:16 PM »
I don't know about the GM stainless. I am not aware of the flash chrome on the Ford trim. Many restorers polish the stainless to a mirror finish. That may look nice to them but it is not that way from the factory. Still shiny but not mirror finish from what I have seen.  I believe the extruded stainless trim is chemically polished when new. More or less it is brighten chemically and not by mechanical polishing. 
Bob Gaines,Shelby enthusiast, Shelby collector , Shelby concours judge SAAC,MCA,Mid America Shelby

Offline J_Speegle

  • Administrator
  • Hero Member
  • *****
  • Posts: 24578
Re: Stainless Trim isn't truly just stainless -- or is it?
« Reply #2 on: February 05, 2020, 02:36:17 PM »
No chroming of trim such as the panels your discussing took place on these cars during the 60's. If so we would have found evidence of it decades ago.

Your comparing more expensive cars and completely different operations
Jeff Speegle

Anything worth doing is worth doing concours ;)