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Ted Mooney, P.E. RET
Pine Beach, NJ
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Cyanide free cadmium plating
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Q. I am a car hobbyist and need to replace my acid-based cadmium plating electrolyte solution. The supplier I used many years ago (10) is no longer in business. As a hobbyist the electroplating chemical suppliers do not wish to ship anything to my house or say an 8 gal. solution is too small to be bothered with. I have several hundred dollars of cadmium anodes that I would hate to dispose of by switching over to a Zinc-based solution & I realize the environmental/health disadvantages of cadmium, but I have been using it for 10 years without any issues until...
I need to replace the solution due to a tank cracking when I was on vacation that was a bit of a surprise on my return.
Any additional formation for an acid-based cadmium formation would be greatly appreciated,
for instance, could/should I start with Cadmium oxide then dilute it myself in sulfuric acid, making Hydrated Cadmium sulfate.
I found the following formation when Cyanide is to be avoided. Is it possible for someone to confirm if the formation will work for an 8-Gal (30.3L) solution?
Hydrated Cadmium sulfate (50g/L) 3.34 pounds
Sulfuric Acid (50g/L) 0.41 Gal
Sulfonated Napthalene (5g/L) 5.3 Oz
Then Gelatin is called for, (10g/L) 10 Oz what type of gelatin should I use?
In addition to the above, can someone suggest a 'brightener' formation? Everything I find indicates purchase from a supplier
Retired Auto Mechanic after 49 years now playing with my cars - phoenix arizona
January 13, 2025
A. Hi. I don't know where you got this reference, but I expect that the sulfonated napthalene and gelatin powder serve as the addition agents, grain refiners, and "brightener".
Most plating texts don't cover acid cadmium, but Lowenheim's "Modern Electroplating"
[on
AbeBooks,
eBay, or
Amazon affil links]
has pretty good coverage about a fluoborate bath. Scholar.google.com has a couple of references, but you'd have to obtain the original articles.
I'm sure you don't want to hear it, but I think it's time to stop cadmium plating ...
• The effluent limitations are ludicrously low,
• You'll probably find cadmium oxide to be dusty, and the last thing you want is biocumulative toxic dust floating around in a residential environment.
• Non-cyanide cadmium is difficult to keep under control, and as a hobbyist you probably don't have much instrumentation.
Maybe you can list those cadmium anodes on eBay.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
⇩ Related postings, oldest first ⇩
I'm a chemistry lecturer at a university in South Africa. A local manufacturer of automotive parts, asked me for information on cyanide-free cadmium plating. Unfortunately all the libraries here have only books dating from the 1940's and earlier when cyanide plating was the only workable option.
Are there commercial processes for cyanide-free cadmium plating? Where can I obtain more info?
Johann L FischerRand Afrikaans University - Johnnesburg, Gauteng, South Africa
2000
Yes, there are commercially viable cyanide-free cadmium plating processes based on cadmium sulphate or cadmium fluoborate. If you go to any of the major manufacturers of plating solutions I think they will be able to offer you a process.
My personal opinion is that switching to cyanide-free cadmium plating is sometimes a mistake because it lulls people into a totally unwarranted sense of security. Yes, cyanide is an acute poison. But cadmium is a cumulative poison.
As common as cyanide cadmium plating is, I've never seen the air filled with cadmium oxide dust in a cyanide shop; and as rare as acid cadmium is, I've already seen clouds of cadmium oxide in cyanide-free shops a couple of times. For the safety-conscious person, this one is a tough call.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. Dear Sir:
I would suggest that the automotive company follow in the footsteps of most of the world's auto makers. That is to eliminate Cadmium completely. The automakers have gone to either zinc plating (with better passivates), or to Zinc alloys such as : Zinc/Nickel; Zinc/Iron; Zinc/Cobalt; or even Tin/Zinc.
In accordance with the Brussels protocol, no automobile in the European Community will be able to be recycled if there is Cadmium plating on it. Further, they also state that Hexavalent chromates will not be permissible passivates for the sacrificial plated coatings. Non-chromate passivates, or trivalent passivates are currently being worked on worldwide.
Ed Budman [deceased]
- Pennsylvania
With deep sadness we advise that our good friend Ed passed away Nov. 24, 2018
A. I have run both cyanide cad and sulphate cad. The output of each was quite similar. The cyanide cad was much easier to keep in balance. The three-component additives that we used are no longer made, not enough demand. It was the very old 3M system.
Current additives use a chemical that I forget the name of, but it smells like dead fish and is a regulated material.
The future is in the alloy zinc. If they are going to drop cyanide, they might as well make the switch to alloy zinc.
James Watts- Navarre, Florida
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