cadmium plating

[ckrantz]

Hello I was wondering if anyone has had experience with cadmium plating or a similar low cost zinc plating. I need to coat break rotors for automobiles and I haven't been able to find many resources for cadmium coating.

[ViperTX]

Why would you want to cadmium plate brake rotors....? For some reason I believe remembering that Cadmium was not approved in many states.....I think that's what I recall...call a Plating Shop.

[miljnor]

Cadmium is REALY poisonous! which is probably why you think it's not approved in most states. I would tend to believe that if California has cad platers anyone can.

Cad. plating on rotors looks cool, and it rubs off of the friction surfaces easily.

[jcolley]

Wanna know the real deal?

Here's how I learned the hard way. I made a few new machinist friends a month or so ago. One of them introduced me to the widow of an old retired Navy Warrant Officer. This guy was a master machinist and did wonders restoring old Norton and Indian motorcycles and the like. Being an old die hard, he preferred to do things the way they were done originally. Like Cadmium plating all the bolts and such.

From what I researched, the plating process is fairly simple, but the primary chemical involved is Sodium Cyanide. Take about 4oz. of Sodium Cyanide and dissolve it into about a gallon of HOT water. Don't get anywhere near the fumes (google sodium cyanide if you don't know why, it's what they used to use in the gas chamber). Then, this is the bath for the plating process. Easy right?

Now, fast forward 20 years or so where this 5 gallon bucket of liquid Sodium Cyanide has been sitting in the garage, long forgotten. After he passed on, his friends came over to the house to help her sort through his belongings and price a lot of his machinery supplies so she wouldn't get ripped off. They look under a workbench and see a white five gallon bucket with a lid and an ominous skull and crossbones on it. "POISON, SODIUM CYANIDE". Everyone sort of backed away and tried to figure out what to do with it. Afte calling around to numerous waste disposal sites, we were a little miffed that people would not take this stuff. Too hazardous. In fact, when we called the local Department of Health and Environment whatever office, they hung up on us. Twice.

Looking into a commercial solution for proper waste disposal, we were asked the exact address of the substance as they would cordone off the route the truck would take and have a HAZMAT team escort it. We didn't bother to ask what the charge would be, just said thank you.

So, more research googling the stuff yielded a web site with instructions on neutralizing it.

You need pH test strips and chlorine test strips, a gallon or so of lye (Red Devil Drain cleaner), about 5 gallons of chlorox bleach and probably at least a gallon of concentrated Sulfuric Acid. Nervous yet? Use the test strips and get idea of where pH is. Dilute the lye about half and half with water and add this to the Sodium Cyanide to raise the pH above 10.5. Chlorox is about 5.5% Sodium Hypochlorate. At 5.5%, you need at least 2 gallons of bleach for about a gallon of sodium. This will produce a violent reaction as the chllrine neutralizes the Cyanide and converts it to Cyanate, which is benign. Once the bubbles stop forming, wait a day for the reaction to complete. Now, the cyanide is neutralized and it is safe to bring the pH down to something that won't eat your pipes. Dilute the sulfuric acid 1 to 1 with COLD water (also a violent reaction...lots of heat) and add it to the mix VERY CAREFULLY. This is the most violent (and the coolest) chemical reaction I have ever seen, so be very careful. Then, once the pH is back below about 8.0, you have a nice group of five gallon buckets to pour down the drain.

Chemical gloves, goggles, and a organic vapor cartridges on a face mask are a must and forced air such as SCBA is preferred.

I have no idea whether or not the cadmium plating is worth anything, but I can tell you from experience that the byproduct is an absolute pain in the arse to get rid of. If Sodium Cyanide comes in contact with any acidic solution it reacts violently and releases Hydrogen Cyanide, a poisonous gas used in World War I as a chemical weapon. The neutralizing process is something I took on myself, after much dissuasion from the chemical engineers in my family. I would never consider making more of this stuff, especially since it cost over a hundred dollars in chemicals just to neutralize another batch. The Air Force base here no longer uses this process on landing gear components for the same reasons.

I may be a little biased, but I am not an environmentalist either (I work in nuclear power plants).

Just my .02

Jim

[ckrantz]

Jim.. WOW.. I think I will pass on the cadmium plating. I had no idea it was that toxic. I guess I will just go with the Gold Zinc or Zinc. I'm going to give caswell plating a call tomorrow to see how expensive it is per rotor to zinc coat rotors.

[miljnor]

its kind of interesting that the stuff is so poisonous. Because a freind of mine used to work in the printing industry for a newspaper printer and they used sodium cynide in their stripping process. (something to do with film developement. This was a few years ago but I would imagin they still use it.

[ckrantz]

Yes, I'm also surprised that the department of environment would hang up on them twice. What do they expect? People to just go out back and dump this stuff? I believe I'm going to go with Yellow Zinc.. its very painless.

[jcolley]

I almost convinced the local dump to take it on their Household Hazardous Waste Amnesty Program, no questions asked sort of thing....except they *do* ask a few questions. Like what is it? After I told them, they said okay...and then talked to a supervisor. Then they gave me the numbers of a couple of commericial disposal companies.

I think the thing that frightened me the most was if you google Sodium Cyanide with the word neutralize, about about half the hits come back with WMD and the middle east. Nice, huh?

Jim

[900steve]

you may want to have a look here:
http://www.caswellplating.com/kits/
it looks like they have these plating kits meant to resemble the looks of the cadmium.
never tried it, but i would love to hear any feedback on how well their stuff works. another option is to make friends with a plating shop and if you have small runs, maybe they'll cut you a break and run them with a larger batch.

but yes, stay away from Cd plating. looks cool, but it's bad stuff.

[ckrantz]

I talked to Caswell about their kits.. I was looking at the zinc kit and didn't even realize that the other kit was a cadmium looking coat.. So nice..! It seems very simple from what they told me..