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Ted Mooney, P.E. RET
Pine Beach, NJ
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Cadmium Plating Q&A Problems & Solutions
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Q. What are these crystals seen on the surface of cad plated parts after plating? Why are those crystals building up?
Mary Marin
- Los Angeles, California
September 11, 2023
A. Hi Mary,
This looks to me like it may be cadmium bloom, which occurs when cadmium reacts with certain organic acid vapors. The most common cause for this is improper storage in certain types of wooden containers. Heat and humidity can cause vapors from the adhesives to diffuse into the air and react with the exposed cadmium. Be very careful! Cadmium is a dangerous poison, and those white crystals can form an inhalable dust when handled.
- Minneapolis, Minnesota
October 6, 2023
⇩ Related postings, oldest first ⇩
Q. I'm doing some small-scale cad plating at home. I'm having problems with getting a "mottled" appearance. What am I doing wrong?
Thanks,
- San Francisco, California, USA
2001
by World Health Organization
on eBay
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Cadmium is a biocumulative poison like lead and mercury, with very similar effects on development. For that reason, it is the law that every worker doing cadmium plating must have their blood periodically tested for cadmium by a physician.
Also, when your rinsewater becomes contaminated, if the city finds you disposing of it in the sewer system, you may find yourself in more trouble than you could possibly believe. Cities periodically sample the sewers for cadmium to track it to its source because of its tremendous and cumulative toxicity, and if their sludge has cadmium in it they must dispose of it in a hazardous waste landfill which costs them a fortune.
Then there is the question of what you will do with the cadmium plated parts. Only the most critical military and aerospace parts are plated with cadmium these days in the USA, and cadmium is completely illegal in Japan and many countries. If your parts somehow eventually found themselves into food service, say on a backyard barbecue grill, it would be very dangerous; there are cases of whole families being seriously sickened from using old cadmium plated refrigerator shelves as barbecue grills.
This finally brings us to your "mottled appearance" problem. No supplier or consultant anywhere is going to assist you in troubleshooting the problem because of the liability. I am having trouble imagining where you were able to buy cadmium anodes and cadmium plating solution as I thought that no supplier had shipped cadmium chemicals to a residential address for decades now. Unfortunately, you also have a major disposal problem as it may cost you thousands of dollars to dispose of even a relatively small cadmium plating bath. Cadmium plating, when vital for critical components where substitute plating would render them dangerous, must only be done in a proper industrial facility. Again, hopefully you're working with an imitation, not actual cadmium -- in which case, ask the hobby supplier for guidance because we don't even know what metal or alloy it is. Sorry again :-(
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I am in the process of an aerospace HND and would like any relevant info on cadmium plating, or where I could find the best source of info. I cannot find any info on cadmium plating equipment, portable or fixed -- any help?
Many thanks.
Alex Caldwell- Reading,Berks, UK
2002
A. What does HND stand for? Cadmium can be plated in barrel or rack, or portable by brush plating. See a text on electroplating for specifying equipment. Cadmium, with it's toxicity problems, has been slated for replacement with other coatings.
Tom Pullizzi
Falls Township, Pennsylvania
A. Please be aware that Cadmium electroplating should not be used in any space application due to outgassing problems in a vacuum. As long as the parts will not go into space there is not a problem except, as stated in a previous answer, there could be environmental issues with the cadmium itself. A few years ago cadmium was banned from a lot of military and commercial applications due to potential toxicity concerns.
David Jones- Canyon Country, California, USA
Can't plate internal cavity
Q. We have parts we want to get cadmium plated; however, our vendors say they can't because of large internal volumes.
The parts are approx. nine inches long, have an O.D. of 8 inches, and an ID of 7.8 inches - the internal cavities are approx. 8.9 inches deep.
Our problem is that our vendors say they can only plate three or four inches deep inside the parts.
The base metal is E4340 - can anyone suggest a good alternative to cadmium plating for this material?
thanks,
product designer - Huntsville, Alabama
September 15, 2008
A. Hi, Jerry. We have many threads here about possible substitutes for cadmium plating; please put "cadmium plating alternative" or " ... substitute" into the google custom search engine to find those many informative discussions. But the thing is ... obviously, nothing has ALL of the properties of Cadmium, and substitutions can only be suggested with extreme care after understanding the full functions of the component.
The problem here is not cadmium plating specifically, but economical plating of an internal cavity. Parts shaped like a topless box are plated all the time; it is possible to cadmium plate these parts ... but perhaps not within your budget. Internal anodes will be required, and perhaps additional handling, like plating with the open end of the hole up, then inverting to minimize dragout, etc. Best of luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. It is possible with additional anode to be given in ID. We are following the same for aerospace components and we are getting the same. If require You can go for even local plating also.
T.Chandra Sekhar Reddyplating shop employee - Mumbai, Maharashtra, India
A. This is not an easy part to plate, so many platers will pass upon the opportunity. It has to be run on a hand rack since it must be plated with the opening up to avoid gas generation being trapped. Parts this size are bulky/heavy which slows down production. It will require several racks made especially for the part. It WILL require an internal anode. Stick cadmium for anodes are very difficult to come by. We ended up casting our own which is a safety problem. Cadmium fumes are toxic!.
Why cad? You might be able to use zinc. EN might work, but would be more costly. Silver is an excellent replacement for cad for most uses, but that is really expensive.
- Navarre, Florida
Cadmium plating roughness problem
Q. We have problem on cadmium plating in inside diameter (bore). The size is 3mm in diameter and 100mm in length. The specification said the roughness should be below 1.00 mm and thickness between 5-9 microns. We have tried to reduce current density to 2 Amps/dm2, but we still got problem, sometimes the thickness is unstable, also the roughness. We used auxiliary anode on bore made from steel. Is there any relation between rectifier ripple and loading quantity (total current used)?
Susie SusilowatiEngineer - Bandung, Indonesia
October 18, 2011
A. Hi, Susie.
Even with an auxiliary anode it is difficult to plate a 3 mm inside diameter 10 mm long because the limited amount of solution inside the diameter can go out of balance very quickly. My suspicion is that the solution is way out of balance long before you've achieved your 5-9 micron plating thickness. I think you will have to force solution flow through the cavity.
Depending on the type of rectifier, operating at a low percentage of capacity can produce extreme ripple. Any rectifier that "chops" the input power as opposed to transforming the voltage (which is most rectifiers today) will suffer this problem. Still, my guess is that this is not the main issue causing the problem that is confronting you. Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. Hi Susie
The first thing I would check with a roughness problem is the state of the filters and look for any holes in the anode bags.
The easy to check for particulate contamination is to get a beaker [beakers on
eBay
or
Amazon [affil links] of solution and shine a beam of light through. Viewed from the side it is quite a sensitive test. Do a search on "Tyndall effect".
Geoff Smith
Hampshire, England
Cadmium Barrel Plating is Gritty
Q. We are experiencing problems with our cadmium barrel plating.
On removing and rinsing parts from the barrel, the finished parts are exhibiting minute particles (grain like) randomly dispersed on the surfaces. There are not embedded in the the cadmium plating but more so on the surface. We have to remove the particles using a fibre glass pen.
The contact bombs on the end of the danglers are covered in grainy particles (sand like) which I believe is contributing towards the particles on the finished components.
What is the reason for the grainy build up on the bombs. This occurs even after 1 or 2 loads. Is it because the bombs are sitting static in the barrel during processing.
Any suggestions as to how to solve this problem.
Many Thanks.
Process Engineer - Crumlin, Count Antrim,Northern Ireland
August 20, 2014
Nodule Problem in Cadmium Plating
Q. We run a sulfuric-acid cadmium process on steel substrates in two separate identical tanks (two plating stations each). We recently dumped one of these baths, suspecting it had become contaminated. Since we made this new bath, we are getting extreme roughness in the form of tiny nodules, which form everywhere except the underside surfaces, as the parts are positioned on the rack. Under magnification, these nodules look like tiny brown warts. If you scrub the area with a scouring pad, the nodules shine up like the surrounding cad plate surface.
We have ruled out cleaning. Parts from the other tank do not have this formation. Bath parameters for temperature, acid and metal content, etc., are in range and comparable to the other tank. No leaks identified. We filter these baths with .5-micron cartridges and have no detectable particulate in solution. Is this some sort of stress formation? So far the only difference we have detected between the two tanks is rectifier ripple: the roughness tank has 8%, while the other is only 1%. Even so, 8% doesn't strike us as alarming, but we are working to bring that down.
We use iridium-oxide inert anodes (instead of graphite), and our cadmium anode baskets are bagged.
Any ideas? Our chemical reps have all but given up.
Bruce Brady- Lincoln, Nebraska, USA
October 27, 2017
CADMIUM PLATING: Rough/ Nodule surface problem
Q. Hi.
I'm doing Cadmium plating (DULL FINISH) for almost 4 years.
Lately, the roughness of the surface doesn't meet requirement.
Condition of cadmium tank:
a) NaOH: 20 g/L
b) NaCN: 108 g/L
c) Sodium carbonate: 34 g/L
d) Cadmium metal : 30g/L
e) Working temperature: 25 °C
f) Filtration: YES, solution continuously filtered through 5 micron string wound cartridge filter.
g) Already done dummy plating for 36 hours at 4amp/dm2. But the result (appearance) still no good (see picture).
Material to be plated is steel and stainless steel. For stainless steel Nickel strike has been done before start plating.
Before going to plating tank, alkaline cleaning, electro cleaning, activation has been done to the parts.
I really need help regarding this issue.
Thank you for your help.
- Selangor, Malaysia
August 27, 2019
Ed. note: No pics received, Izzuddin :-(
Cadmium anodes turn black only during plating
Q. What would cause a black film to form on cadmium anodes while plating that would dissolve very rapidly off the anodes when plating is complete.
Don DavisAmerican Airlines - Tulsa, Oklahoma
February 12, 2020
A. Hi Don. This might depend on whether the bath is cyanide, acid, Ticad, LHE ... so it would be helpful to know. Thanks.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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Q. The plating solution in respect to the post is LHE cyanide cadmium. The film does not seem to effect plating efficiency or HE. Don Davis [returning]American Airlines - Tulsa, Oklahoma A. In a common cyanide cadmium solution the anodes turn black when the free cyanide is too low. Get it back up to about 18 oz/gal and the metal around 3 oz/gal, try it in a bucket first and see if the black goes away and you see clean cadmium color.  Robert H Probert Robert H Probert Technical Services  Garner, North Carolina  |
A. Maybe it's turning black because you apply high (very) voltage? After you switch off, the anode turns to normal?
Izzuddin Jaafar- Selangor, Malaysia
March 2, 2020
No cadmium plating coverage on large or rough parts
Q. We have encountered a problem with our cyanide cadmium plating. After 20 mins of plating with 25-35 °C temperature and 2-5 Amps, still the plating is missing on several parts of the job. Plating happens well on small and smooth surface parts but not on un-smooth surfaces and large parts. Keeping in mind that the job is well stripped and degreased before plating. We have some critical jobs pending I would like to hear your valuable opinions.
Zeeshan Ahmad- Islamabad, Pakistan
September 14, 2020
Q. We analysed this specific bath and the analysis result shows that every content of the bath is in range. The composition of the bath is mentioned below.
Bath composition :-
Solution Volume :- 576 litres
CaO : 35-40 g/ltr
NaCN : 90-120 g/ltr
NaOH : 20-30 g/ltr
Additives: NiSO4 : 1kg
- Islamabad, Pakistan
September 14, 2020
A. Hi. I try to give my opinion.
What is the material of the parts?
What is required thickness of the plating?
My opinion,
Plating current is not enough. 2-5 Amps is to low for big parts. It's working well in small parts, but not in big parts, since your surface area already changed.
Use CURRENT DENSITY (need to calculate to set your current based on surface area of the part) between 20-30 ASF (ampere per square foot).
Refer to the jig picture, it was difficult design for me. It is better to use one hook jig only, and try to rotate the part in interval time of five minutes.
If, after applying above steps, you need to setup new anode that located at the very deep area (plating hard to reach/ cover).
Thank you.
- Selangor, Malaysia
Q. Hi,
I'm working for ITT Cannon as Plating Engineer for the Cadmium cyanide Process. Recently we got in 5 of our cad tanks a pitting condition around Hull Cell and Parts,; the pit condition is around all the cell (High current density and low current density).
We try to fix using Metex S-3 as cadmium wetter. It works but it does not resolve the pitting condition, we made dummy plate every day since February 2021 with Carbon filtration and i'm looking for advice if the Lead (lead comes from Cad Anodes) could be an issue?
I hope that someone can advise us.
- Nogales, Mexico
April 6, 2021
A. Hi. If the wetter doesn't relieve the pitting, I'm guessing they are not gas pits (which would be hemispherical and shiny). But if they are, and they are also on the Hull Cells (which don't get exposed to any polishing/buffing changes you might have made), then it remains as something wrong with the wetter. Are you able to do dyne testing?
A good close up picture of the pits would probably help get us all on the same wavelength, but if the Hull Cell panels do not enter your standard pretreatment baths, clearly the problem is in fact with the cadmium plating solution.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Cad plated parts with yellow chromate look like they were not rinsed properly and allowed to dry.
Manufacturing Engineer - Lancaster, Texas
February 8, 2022
A. No, it looks like he did not neutralize the cyanide plating solution before going into the yellow chromate solution. Good practice requires a weak nitric acid dip ahead of the yellow chromate, but most job shops do not maintain the acidity of the weak nitric pre-dip.
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
Thank you very much Mr. Probert.
This is a job for the military and is supposed to be Cadmium Plated per AMSQQP416, Type II, Class 2
Manufacturing Engineer - Lancaster
Ed. note: This is only one of 60,000 threads on finishing.com; we have several threads focused on specific cadmium plating problems like topic 47214 "Cadmium plating turning black" and topic 36051 "Cadmium plating blistering/adhesion problems". Please search the site for "Cadmium plating [specific problem]".
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