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Allowable ppm of metallic contamination in nickel plating bath

(-----) 2004

Q. Hello ...

What are the numerical values (ppm) of the iron, zinc, aluminium and another metallic contaminations in nickel bath? What are the threshold values optimum and maximum? I searched this question's answer but I couldn't find it.

Could you answer this question?



Emre Tuna
engineer - Istanbul, besiktas, turkey


A. Optimum would be zero, Emre. Unfortunately, the real world doesn't have go/no-go gauges where 49 ppm is okay and 50 ppm results in failure. The Metal Finishing Guidebook has some answers, and The Canning Handbook has more detailed information, and also reveals that the sensitivity to particular contaminants depends to an extent upon the particular brightener systems used. If you use proprietary solutions, the technical data sheet should contain these numbers.

To expand upon your question just a little bit, probably the preferable thing to do is to frequently run Hull Cell test panels -- and then you will see the effects of this contamination in the lab before it becomes it becomes an actual problem on production parts; your technical data sheet will then give you hints at what is causing the Hull Cell problems, you will remove the contaminant on a sample per the instructions, and verify what levels of contaminant cause problems at different current densities. Good luck!

Please come back and tell us the results.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey


A. It depends on your customer. If you are plating 24K gold, it is probable that the contaminant level could be sub part per million. If is a commercial plate job of some metal, the contaminant level could easily be where it affected the cosmetics of the plate. Another limitation is the point where it poisons the bath to the point of slowing down the plate rate too much.

In short, it will be very specific to your plating application and your customer.

James Watts
- Navarre, Florida


A. Mr. Tuna,

Mr. Mooney is (as usual) right. I've had several different brightener systems for my nickel tanks. Some were somewhat tolerant of contamination (zinc is my biggest problem), and some would show the effects at very low concentration (zebra stripes and dark plate in LCD @ [Zn]>5 ppm). My current brightener can plate acceptably at < 80 ppm [Zn}. If you are plating zinc die castings and you anticipate parts falling into your nickel tanks, I would purchase a small electrolytic purification cell for continuous low current dummy loading. It has helped my operation. In any case, contact your vendor. Good Luck.

Trent Kaufman
Trent Kaufman
electroplater - Galva, Illinois



1. Al 60
2. Cu 40
3. Lead 02
4. Zn 50
5. Iron 150
6. Hexavlent Cr 10

ajay raina
Ajay Raina
Ludhiana, Punjab, India


Q. Hello Mr. Mooney...

Thanks your answer. I absolutely agree with you. But I have some hesitations. We plate door locks whose base metal is iron, zinc die castings and brass. When we chemically maintain every weekend the nickel baths, I find lots of parts fall over the bath. And our tanks are made from PP. When you look at tank/bath edges you can see redness. And plated parts have little pits. So,I assume iron contamination is high in nickel baths. But, when I run Hull-Cell test panel,I don't see any sign from iron contamination like pits or hazy deposit. And more interesting, when I measure iron and zinc contamination with spectrophotometer (Odyssey DR/2500), I find amazing results;

Total iron (in Rack)........4 ppm
Total iron (in Barrel)......22 ppm
Total Zinc (in Rack).......Underrange
Total Zinc (in Barrel).....0,33 ppm

What do you think about these results? Are these results and situations normal?

Could you help me?


Emre Tuna
- Turkey


Q. Hello Ted Mooney... How are you? If you remember,I had asked this question a few days ago and you had answered. In your answer, you had wanted some trying from me. I struggled for this trying a few days. And I send results about tryings. But you didn't turn me again to re-answer. I think you forgot it or you haven't any time. If you possible, could you look at results and give me some explanations?

Thanks Sincerely,

Emre Tuna
- Turkey


A. Hello again, Mr. Tuna. Yes, sorry I was away; but I think your question was well answered by Mr. Raina and the other respondents.

"ASM Metals Handbook Vol. 5 "Surface Engineering" [affil. link to book on Amazon] gives generic values for iron contamination of 5 ppm as normal and 50 ppm maximum, and zinc contamination as 1 ppm normal and 10 ppm maximum. The Metal Finishing Guidebook says 50 ppm maximum for each. But as related by Mr. Kaufman, these values really depend on the particular nickel plating solution.

So your contamination values sound quite normal. I don't think metallic contamination is a major cause of pitting anyway. Besides insufficient agitation or wetting agent, other causes are porosity of the substrate, organic contamination, too much acid or too little nickel, particles in solution, or parts not being clean.

Because the Hull Cell panels look good, and you have trouble with both brass and steel parts, I'd suspect part cleanliness. Are you sure you see a waterbreak-free surface on the way into the nickel plating tank?

opinion! Parts should not be allowed to fall off the racks, and should certainly not be allowed to dissolve into solution. This is a 1960's situation, not acceptable in this new millennium. If you make it a policy to stop the line and "magnet it" immediately every single time a part falls, you are on your way towards corrective action of no more parts falling. If you talk yourself into some particular number of parts being allowed to fall off the racks before it is a problem, you've already lost the QA war :-)

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey


A. Mr. Tuna,

This message is long so grab a snack from the kitchen before you start!

The nickel sulfamate solution I use has the following contaminants:
Calcium <5 mg/L Cobalt <1 mg/L Copper <0.5 mg/L Iron <4 mg/L Lead <1 mg/L Manganese <0.5 mg/L Zinc <2 mg/L Ammonia 180 mg/L Sulfates 0.1 percent

This is directly from the manufacturer. Once I get the solution I dummy plate onto a corrugated plate at 5 A/sf and 0.5 A/sf to preferentially remove metallics such as copper, iron, etc. I also run continuous carbon filtration to reduce the organic contamination. The only catch is that you have to monitor the surface tension of the bath since wetting agent is removed by the carbon filters. After some time the filters become partially saturated with the wetting agent and consume less but, from experience, are still effective at removing organics.

As for your problem, pitting and hazy products I can offer you my experience. I believe I read another post of yours where you stated you electroform rather than plate. If this is incorrect I apologize.

I electroform optical reflectors for the projection market. For our first generation reflector module I used rotation and masks to achieve uniform reflector thickness. When we were in high production the motors were running nearly continuously. This caused the motors to become warm which caused the grease and lubricant to become less viscous. Over time a small trail of oil made its way down the rotating shaft and into the bath causing an oil slick on the surface. When a mandrel was lowered into the bath the surface received a thin coating of oil/grease. The result was a hazy optical surface. If I remember correctly pitting was also observed.

My suggestion to you is to dummy plate to remove metallics run carbon filtration while washing the surface of the bath with your wetting agent. The wetting agent will trap the organics so they can be filtered by the carbon. Also check your agitation.

Best regards,

Christopher Jensen
- Bohemia, New York, USA

January 4, 2014 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Dear Sir,

How much metallic impurities (PPM) are allowable in Nickel Plating solution. And is it applicable for continuous nickel plating process on CRCA steel strip.
Please suggest .


Sastry VSA
- Hyderabad, Andhra Pradesh,India.

January 20, 2014

A. Hi Sastry,

Below metallic impurities tolerance for your ref:

1. Iron <150ppm - Speckling surface.
2. Aluminium <60ppm - Reduce limiting CD and create rough deposit.
3.Zinc <50ppm - Whitish or dark deposit at low CD area and shiny black streaks on deposit.
4. Copper <50ppm - Dark deposit at low CD area.
5. Hexavalent chromium <10ppm - Skip plating at low CD area.
6. Lead <10ppm - Dark, brittle and poorly adherent deposit.
7.Stannous tin <10ppm - Dark deposit at low CD area.


David Shiu
David Shiu
- Singapore

Accidentally put pickle aid into bright nickel plating tank

April 21, 2016

Q. Dear Sir

I have accidentally added 5 ltr of pickle aid to my bright nickel vat which is 1300 ltr. I have started the carbon treatment; it has been 4 hours and I plan on treating it with carbon for the next 24 hours.

Is there any way that my solution can be saved, or does this mean I have to dump and start fresh?

Hama ali
- United kingdom

April 25, 2016

A. Good day Hama.

That all depends on the make-up of the pickle solution. What are you pickling, steel? Check for iron. What is the composition of the pickle and is there a wetter involved (organics)? Have you run hull cell panels on your bright nickel and analyzed for chlorides, pH etc.? More info would be helpful. I would try peroxide/permanganate with the carbon. What concentration carbon, temperature etc

Eric Bogner, Lab. Tech
Aerotek Mfg. Ltd. - Whitby, Ontario, Canada

April 27, 2016

A. Hi Hama,
Peroxide/permanganate and carbon treatments are for removal of organic contaminants. They will not help with your problem.
If you give us a clue what your pickle bath is and what was treated in it we might be able to help. But the only safe option is to replace the bath.

geoff smith
Geoff Smith
Hampshire, England

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