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topic 28851 p2

Process of Zinc-Nickel Plating

A discussion started in 2004 but continuing through 2018

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March 31, 2016

Q. Hi all. I have a question about zinc-nickel plating. We are making a part and have to send to our finisher for getting zinc-nickel plating. This part has two PEMs; if we use zinc plated PEMs, after plating the color of PEMs turn black. I do not know what is the reason? Material of PEMs, thickness of zinc on the PEMs, or washing time and composition before plating?


peyman basirian
quality engineer - vancouver, BC, Canada

April 12, 2016

Q. We are facing problem in Alkaline Zinc Nickel Plating Self Tap screws M5 x 18 . Carbonitriding process with 340 HV hardness. Even after 3 Hours of Plating coating thickness found 2 - 4 Microns in the parts. Load Qty : 40 Kgs Current : 500 Amps.

Any suggestion to overcome this problem.

Geetha Muthuramalingam
- Tamil Nadu India

June 14, 2016

Q. Hi,
We are doing zinc nickel plating on alloy steel components. Some of these components have tubular shapes and cavities about 40 mm in dia and 50 mm deep. We are getting zero thickness in the inner side of these cavities and the salt spray fails within 120 -150 hrs. On the outside, the thickness achieved is around 25 - 30 micron and the salt spray test is also okay from the outside area only. Can you please suggest any remedy to achieve thickness at the inside area of these parts. Voltage = 4 - 6 V. Time = 30 minutes.

Yasir Khan
- Karachi, Pakistan

July 14, 2016

Q. Dear sir .
Please help me regarding acid zinc-nickel. I am starting acid zinc-nickel plating in barrel plating; I don't know what are the standard parameters of this bath, and some problems face me every day. After 2 barrel plating the fastener threads are not bright and if I am doing Hull Cell test then Hull panel LCD area is full dull. What should I do I don't understand. Please help me with standard bath parameters and maintenance of acid zinc-nickel bath.
Thanks sir .

amit awasthi
- mumbai , maharastra , india

A. Hi, Amit. The supplier you are purchasing your zinc-nickel plating process from will have a "technical data sheet" instructing you how to operate it. It's a fairly complex process because you don't just need the right thickness and brightness, you need to maintain the correct percentage of nickel in the deposit or it will not offer the proper corrosion resistance. Good luck.


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Ted Mooney, P.E. RET
Pine Beach, New Jersey
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July 22, 2016

Q. We want to use Zn-Ni Electroplated coating for our clamps and thinking to get the 25 µm to 30 µm Zn-Ni electroplated coating thickness with 12 wt% of Nickel content. Does this thickness improve the corrosion resistance purposes or it's detrimental? Should we need to adhere to 8 µm to 14 µm coating thickness to achieve the optimal performance?

John Stacey
- Sydney, Australia

December 2016

A. Hi John. For standard zinc plating there is no doubt that 25 microns is better than 8 to 14. Standards like ASTM B633 [link by ed. to spec at TechStreet] call for 5 microns for mild exposure, 8 for moderate, 13 for severe, and 25 for very severe. To my knowledge 25-30 microns of zinc-nickel is not deleterious, but you might check with your supplier because there might possibly be difficulty with chromating, roughness, or something else they caution you about for their process at that thickness.


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Ted Mooney, P.E. RET
Pine Beach, New Jersey
We need "Aloha" now more than ever

December 9, 2016

Q. I am trying to deposit Zn-Ni on 4 inch x 2 inch CM steel sample using a chloride bath with pH 5.5-6.0. I am plating two samples simultaneously using a 15 L bath. I am seeing black and burnt coating at the bottom up to a height of nearly 1.5cm. Kindly suggest how to overcome. I am using a filtration system and the cathode movement is very slow.


Manju Srinivasan
- UP India

December 20, 2016

A. Hi Manju,

Please enlighten us with:

- Barrel or rack plating?
- Acid Zinc-Nickel: which nickel percentage (low or high)? Do you test in hull cell? What are your parameters (potassium chloride, metallic zinc, voltage, time, temperature)? Do you test for iron?

I think that we can help you if you can give us more information.

Best regards!


Daniel Montanes
N FERRARIS S.A. - Canuelas, Buenos Aires, Argentina

January 13, 2017



January 2017

A. Hi Gagadeep. Are you a highly experienced zinc plater venturing into zinc nickel? Sorry, but those 10 words don't comprise a realistic request. Please start with a few paragraphs summarizing your situation and what you know and don't know about the subject, and hopefully we can begin a back & forth and make some progress. Good luck.


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Ted Mooney, P.E. RET
Pine Beach, New Jersey
We need "Aloha" now more than ever

January 13, 2018

Q. Respected sir, I'm running acid zinc nickel plating. All parameters are maintained, but after plating a white salt appears on plated parts both before and after passivation. Please tell me the solution.

Kamaldeep singh
- Delhi india

February 26, 2018

Q. I'm having difficulties of high insertion forces (8-12 kn) of a steel tube into an Aluminum housing. The tube with ZnNi plating per Ford standard WSS-M1P87-B4.
Ra =0.9 vs. a normal zinc plating of 0.2.

The tube diameter is 19.03 mm in a machined hole of 18.950 (0.080 mm interference)

A normal Zinc plated tube is inserted with 3kn.

The total thickness of the plating is 0.017 - 0.024 mm.

The inorganic sealant is FINIGARD 200A.

I get values of chemical composition of a 12.4 % nickel concentration in plating.
It looks like it has a Cr 0.06 layer after Zn-Ni..

jaime puente
Bocar - Mexico City

March 14, 2018

A. Hello Jaime!

Finigard 200A has an (approximate) friction coefficient of 0,22. This is a little high for this application. Talk to you vendor to use another sealer with a friction coefficient more like 0,12-0,10. I think that with this values you will have a better (and stable) performance in this application.

Best of luck!

Daniel Montanes
TEL - N FERRARIS - Canuelas, Buenos Aires, Argentina

March 3, 2018

Q. Sir, we [don't know?] required SST life of (MFZn Ni 1 - B) Zinc Nickel plating salt spray life, like for white rust and red rust, because we have not found HES D2003-03 [Honda Electroplating Standard (for corrosion prevention, rust prevention and decoration)].


March 14, 2018

A. Hi Ravinder. If you are a Honda supplier, ask for this spec. They should give it to you because they are the only source of up-to-date Honda specs. I don't recall the "B" in ZnNi Honda specs, so it may be a new type of topcoat or a typing error.

Best of luck!

Daniel Montanes
TEL - N FERRARIS - Canuelas, Buenos Aires, Argentina

Black spots on ZnNi plated parts from water soluble cutting oil

August 20, 2018

Q. Issue of black spots on ZnNi plated parts when comes in contact with water soluble cutting oil, please guide what is the element which which causes the same from either cutting oil or plating.

laxman Ramdasi
- india

August 20, 2018

A. Hello Mr. Ramdasi,
Some waterborne cutting fluids can be rather caustic. They may contain detergents, and also substances to prevent mould growing. To begin your troubleshooting, you should determine the pH of the fluid in question. That information will give you a clue as to what the reaction could be.

Rachel Mackintosh
Plating Solutions Control Specialist / Industrial Metals Waste Treatment - Brattleboro, Vermont

August 2018

thumbs up sign  That was a concise and practical answer, Rachel. Should have thought of it myself … maybe I will next time :-)


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Ted Mooney, P.E. RET
Pine Beach, New Jersey
We need "Aloha" now more than ever

August 21, 2018

There's a first time for everything. Even brevity ;)

Rachel Mackintosh
Plating Solutions Control Specialist / Industrial Metals Waste Treatment - Brattleboro, Vermont

Black patches, pit marks on Zn-Ni plating

September 4, 2018 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Dear all,
we are suffering quality issue black patches, pit mark and rust on Zn-Ni plating.
Due to this issue, we get much more rejects.
Kindly anybody suggest a reworkable method to remove black patches.
So suggest how to remove black patches.

Mangesh taware
employee - pune, india

September 2018

A. Hi Mangesh. For some fast ideas, please read this thread which we appended your inquiry to.

To take it further, please give us some data: pictures of the defects, substrate material, barrel vs. rack plating, alkaline vs. acid plating, chromate and sealer details. Is this a problem that just came up or have you been suffering from it for years? One reject per hundred parts or 99?

I'm not sure if we have a language difficulty or if you are actually looking for a salvage method rather than corrective action, so please clarify that point. Thanks.


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Ted Mooney, P.E. RET
Pine Beach, New Jersey
We need "Aloha" now more than ever

September 5, 2018

Q. Dear sir,
We are facing pit mark , black patches on zn- Ni plating from last couple of months.

28851-3c 28851-3b 28851-3d 28851-3a

Please share with me your experience how to remove black patches from plating permanently.

Until the problem is solved, could you tell me about any rework able method available to remove black patches temporarily because percentage of rejection is 50%

Mangesh taware [returning]
employee - pune, india

September 22, 2018

A. for black spots or pits on your alkaline ZnNi plated components, your ZnNi bath might be low in caustic -- this for me is the most common cause of blackness in the final product. So ensure you do a thorough bath analysis and check your level of Zn and caustic in your zinc nickel bath, then you can add a calculated amount of caustic or zincate concentrate. Also, ensure your pre-treatment process is effective,

I do hope this is helpful

Oladimeji Isaac
- Osogbo, Osun State, Nigeria

September 2018

thumbs up sign  Thanks Zik.


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Ted Mooney, P.E. RET
Pine Beach, New Jersey
We need "Aloha" now more than ever

September 29, 2018

thumbs up sign Thanks ZIK sir.
After checking all parameters, definitely will come back with you.

Mangesh taware [returning]
- pune, Maharshtra, india

October 5, 2018

A. Kindly Check your Pre-treatment -- maybe acid pickle concentration is not in desired range.

Rahul Potphode
- Pune, MS India

November 7, 2018

Q. I am seeing a similar situation with AISI1008 machined products displaying black spotting qite significantly.

Can anybody comment on whether this would impact on the integrity of the base metal?

Randhir Singh
- United Kingdom

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