The Stovebolt Site Forums The Shop Area General Truck Talk More zinc plating

Started working on some of the larger pieces today and am pretty happy with the results. This is the hood hinge support that I dipped partway into the electrolyte as an experiment. I still have just a 1 gallon bucket, but do have a 3 gallon on standby to be able to immerse the larger stuff completely. We'll see how that works.

The photo shows the support after 2 dips, one deeper than the other by about 2". There's no evidence of a visible mark at the shallower dip (toward the right), so that means I can do things part at a time if needed.

Do you have a link to your zinc plating process? That looks pretty good.

Here's what I used. Link
He blasted his parts prior to plating, but I just derusted them with Evaporust and wire brushing. I tried plating the springs for the hood supports and window regulators, but apparently without blasting the surface to roughen it up I couldn't get the zinc to stick that well to them.

Interesting. Thanks for sharing.

I agree, very interesting. Keep us posted on your progress!

Very neat process. Thanks

Not to start slinging monkey wrenches, but weren't those parts cadmium plated originally?

:dodging monkey wrenches:
They might be Carl, but zinc works for corrosion protection also. Cadmium plating probably needs nasty chemicals, and cadmium is toxic as well. I'm not going to mess with that. Nuts and bolts are zinc plated, even the ones you buy today. I think these will last my lifetime.

Finished up that hood support today. Here's some more pics. There are a few shadows, but I expect them to disappear as the zinc weathers a bit. There are also a few spots where the zinc flaked off when scrubbing after the first dip, especially on the arm opposite the mounting bracket. The second coating pretty much fixed that. I think it was because of the smoothness of the metal. So a light blast might help avoid that.

on edit: that's a tiny aquarium pump in the bucket to keep the electrolyte stirred up.

Kevin, I too want to thank you for sharing this.

Carl, I did a little experiment, dipping the original bracket in muriatic (hydrochloric) acid. It took the plating off very quickly.
According to this video, zinc reacts quickly with the acid, while cadmium is not nearly as reactive. So based on that, these brackets were originally zinc plated.

So the monkey wrenches are successfully dodged.

Interesting process . Looks great

Cadmium is a sacrificial plating. Its design is similar to a sacrificial anode. It protects the underlying steel by its own slow degradation.
After 70 years, cad plating on a hinge would be extremely thin, if present at all. It wouldn't take much to remove what is left of it.
I have an original hinge which has most of its cad plating on the underside of the bracket which mates to the cowl. It was preserved by the dumdum putty which was applied there originally to prevent water from entering the cab via the over-sized holes in the cowl there. It does not look at all like zinc plating, but is somewhat silvery in appearance. The rest of the hinge was raw rusty metal.

Nope, it was definitely zinc plating on my originals. Zinc is a sacrificial plating as well.

Based on the difference of the reaction between zinc and cadmium with hydrochloric acid, it was definitely zinc. Did you look at the video I linked to?

Kevin,

Thanks for taking the time to describe this plating process. It looks very interesting and also very doable for the hobbyist. It does appear that zinc adhesion is enhanced with a media blasted surface. How do you know when the process is over, or does the zinc plating continue to get thicker with emersion time?

I have to admit when reading this, I had an amusing mental image of a mad alchemist working with an assortment of chemicals in a deep dark abandoned Alaskan mine. Who knows, maybe you will strike gold!

Thanks again!

Paul

The process I linked to said a 15 minute run was good. Another source mentioned a long run tended to get "feathers" on the part from excess zinc that just comes off in the rinse and polish. The parts get a soft grey color as the zinc deposits on them. Areas that are shadowed (not visible to the anodes) tend not to get that nice grey color, but are darker. Then a rinse and scrubbing with a brass brush gets them nice and shiny. A second 15 minute run gets a good layer of zinc on them before a final rinse and scrub.

I haven't turned in to that mad scientist yet, but give me time. LOL

For Carl: Here's a photo of an original hood support next to the one I zinc plated. Notice the original plating right around the rivet of the one in the foreground versus the bare de-rusted steel to the right. Not much difference in appearance from the new zinc.

Glad to hear that you are happy with it. I need some historical verification what they were plated with before I go to this extent to restore my hinges.

OK Mr. Doubting Thomas ...er Carl. You could do a test with hydrochloric acid on the remaining plating on yours. It would tell you that they're very likely zinc plated. I don't think you'll be able to find any historical verification. It was 70 some years ago.

Kevin,

I can't speak directly about your hood hinge plating, but the nuts and bolts for our trucks were for the most part Cadmium plated.

Mike B

"Doubting Thomas". I can accept that I suppose. I have been called a lot worse earlier this afternoon, such as apparently I don't vacuum often enough, but when I do, I don't do it right...
The bottom line for me is that the discussion on this fine site of what is original on Advance-Design trucks should be based on historical fact. This site has always been a great place to express our opinions for the purpose of discussion. Without historical documentation, personal opinions should be presented as just that, but not as the end of the discussion.
A lot of people use this site to get the skinny on what is original. We owe them due diligence to help them find that.
I don't know for a fact what the hinges were plated with. I have an opinion of what I believe that they were plated with, and I try to express this as just an opinion, not proven fact.
Carry on.

Cadmium plating was frequently used on hardened fasteners in industry as cadmium does not promote hydrogen embrittlement to the degree that zinc plating would..albeit both processes require a post plating embrittlement relief bake.
For us guys zinc plating is what works best IMHO and could have been the norm back in the day. Industry had both Cadmium and zinc plating shops.
Cadmium plating has been under the watchful eye by the EPA in the US and banned in the EU so getting something cad plated today could be costly.
70 years ago EPA and OSHA weren't on the radar as they are today.
So does it really matter?

For a definitive test for cadmium, one could use this.

But I'm pretty confident in my hydrochloric acid test. Zinc is highly reactive in the acid, and per the video I posted, cadmium is not nearly as reactive.

I can't say that some hinges and other hardware were not cadmium plated, but I can say with confidence that my original hinges were zinc plated.

I was thinking about where I might of found cadmium on my ad
To date I can’t think of any bits that would be
It seems to all be paint, zinc or nothing, and in some places zinc so cheap they didn’t even put copper under it
Zinc is poor adhesion to steel directly but can be sufficient if the alloys and surface prep is compatible

If someone knows a definitive place there was cadmium let me know
I would be curious to find out
Thanks
-s

I'd be tempted to spend the 30 bucks on that test kit I found, but they'd probably want another $30 to ship it to me. Actually their site says free shipping.

Like I said, I'm pretty confident in the acid reactivity test.

I've only found a couple of spots where the zinc didn't adhere well, as on the spring steel.

Great question!
For me personally, it does not matter. I am not going to spend the money or risk the health of humanity by cad plating my parts. I just paint them with Rustoleum self-etching primer and follow up with Rustoleum Metallic Silver paint which matches what I found under the putty used between the hinge and the cowl.
This topic would matter to someone who is restoring his truck to as-built condition for judging by experts in the field.

Got the door latches I resurfaced plated today. I think they came out pretty good. The inner workings didn't get much zinc on them because they couldn't see the electrodes, but the part that counted where I welded and reground came out pretty well. Most of the latches are concealed, so I'm not worried so much about the shadowy spots. They should give some decent corrosion protection over bare steel.

Here's before and after pics of one of them. Even the remaining original plating on the side where the remote connects covered up nicely.

Latch looks great.
You have the process and racking of the parts pretty well dialed in!

Kevin-- thanks for the link! When the weather starts warming up more I will have to experiment with this. How many anodes are you using in your 1 gallon setup?

I have two anodes, one on each side. You need to be careful about getting the anode too close to the workpiece to keep from "burning" it. And definitely don't let the workpiece touch the anodes.

Kevin, I went back through the detailed description of the process in the link that you provided and the author mentions the "burning" without any further description of what this is referring to. Other than being something to avoid what does this mean? Does it damage your original part in some way or is it just an area of improper plating? I'm wanting to learn from other's mistakes because I make plenty of my own!

If the anode and workpiece are too close, especially on a corner, the zinc deposit is fuzzy and black, instead of the light grey even coating. It doesn't really burn anything, but doesn't deposit well.

Here's the latest item I plated. A hood latch that i bought from another member 'cause mine was trashed. It had a little rust on the lever and some of the original plating was gone in a couple spots. Otherwise it was in good shape. I didn't get a "before" pic, but it looks new now. Had to do it in stages, because my bucket wouldn't fit the whole thing.

Just to close the loop on what things were plated with, I was browsing on the master parts list and on nuts and bolts, it does say they were cadmium plated, but is silent on things like hood hinges and latches as far as plating.