-- The Home Page of the Finishing Industry

on this site
current topics

60,000 Q&A topics -- Education, Aloha, & Fun

topic 2886 p.3

Problems in cyanide copper plating

< Prev. page          (You're on the last page of the thread)

A discussion started in 2001 but continuing through 2020

October 29, 2016

Q. Hello... In copper cyanide plating I am facing multiple issues.

At first I was facing issue of low throwing power. At low current density areas I was facing issues of low coverage.
After that I decided to add 1 kg of sodium cyanide to the solution.
After this the issue of covering has been solved. But now the job is having burnt likes patches. I cannot recognize it as burning or something else. But you can say that it is like roughness all over the job.

The tank is of 650 litres.
Should I add copper cyanide to the bath.

I had never made addition of caustic to the solution.
Does caustic helps in increasing throwing power.
Does caustic causes roughness on the job?

What is the main sodium thiosulphate in cyanide bath.
Is there any regular addition required.

Nikhil Sharma [returning]
- jalandhar, punjab, india

December 1, 2016

A. If your free cyanide is OK (1 - 1.5 oz/gal, if memory serves) you might try adding some Rochelle salts (sodium potassium tartrate).

This is not easy to test for; a modest addition (0.5 oz/gal) will not hurt.

dave wichern
Dave Wichern
Consultant - The Bronx, New York

December 6, 2016

A. Good day Sikhil.

From your photo, it is apparent that this bath is an acid copper. The anode bags appear to be blue in colour. If this is true, do not add any more cyanide.
In cyanide copper baths, hydroxide will increase bath conductivity, aide in anode dissolution, causing the metal content to rise. Watch the pH here.
Rochelle salts act as a grain refiner, and also aid in anode dissolution, causing the metal also to rise.
In acid copper baths, the ratio of sulfuric to sulfate is important eg: 1:4 max., as sulfate has a limited solubility. What is the chloride content, and are you within range of the brighteners/carrier concentrations?
Come back with more specific info.


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

December 1, 2016

Q. Hi,
I'd like to have more information regarding Mr Robert H Probert's suggestion to use pure zinc to plate on zinc cast alloy's. Is it melting zinc or is it acid zinc?


Anders Sundman
Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika, Sweden

December 2016

Hi Anders. I'm sure Robert is speaking of zinc electroplating not hot-dip galvanizing. Electroplating of zinc castings with zinc is also often done before chromate conversion coating instead of trying to directly chromate conversion coat the casting.


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Aloha -- an idea worth spreading

December 5, 2016

Q. Hi Ted,

Did you know if it in cyanide, acid or alkali zinc they plate zinc castings?


Anders Sundman
Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika, Sweden

December 2016

A. Hi Anders. Several respondents on letter 16200 recommend alkaline zinc plating of zinc diecastings before chromating. Although I am not personally familiar with Robert's idea of zinc plating zinc die-castings before copper plating, from that it would seem that alkaline zinc would be the best process.


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Aloha -- an idea worth spreading

Cyanide copper plating pits in low current density areas

December 15, 2016

Q. I have tried carbon treating my cyanide bath. It has helped a bit. But the problem is not solved completely. At low current density areas. There is pitting-like patterns. The problem is coming on flat surfaces at low current density areas.
At high current density areas, there is no pitting.
The pitting looks like small dots all over the surfaces of low current density areas.

I am not using Rochelle salt at all.
My bath is completely based on copper cyanide and sodium cyanide.

There was no such problem in the beginning.

Whenever problem arises I add 5 kgs of copper cyanide and 7.5 kgs of sodium cyanide. It generally resolved my issues in the past.

But now carbon treating and additions of copper cyanide and sodium cyanide is not helping.

While carbon treating I had used 500 grams to 650 liters of solution.
It is adamant to the solution?

I had also tried dummying.

In the dummy also small bubbles like roughness is appearing on low current density areas.
Is this pitting because of impurity or I need to add some copper cyanide and sodium cyanide to the solution?
Please help me out.

Nikhil Sharma [returning]
- jalandhar, punjab, india

March 20, 2017

Q. Hi.

Sorry, I have another request about copper cyanide bath: after plating and hot drying, the workpiece's color converts to orange.
Can you help me about this problem?

Asmaa el-sayed
Chemical Engineer - Alexandria, egypt

April 11, 2017

Q. Hi,
I am Facing problem each time I put sodium cyanide in copper cyanide bath, it converts to brass deposit.
Analysis sodium cyanide 99.9% and there isn't zinc, and if we put sodium in another copper bath it's ok
Can you help me about this problem in the bath and the source of zinc ions?

Asmaa el-sayed
Chemical Engineer - Alexandria, egypt

April 17, 2017

A. Hi Asmaa,

Zinc ions might come from copper anode or other plating accessories like anode basket, heater, circulation pump, etc.


David Shiu
David Shiu
- Singapore

April 26, 2018

Q. Sir,
I have problem in my cyanide copper plating bath. The problem is colour of plating is getting reddish. How to solve this issue? Kindly give me suggestion to solve the problem. Copper metal is 48.5 g/l and free KCN is 8.5 gm/l in strike bath; and 46.9 g/l and free KCN is 9.10 g/l in main bath.

Nilesh mavani
Baroda, gujarat, India

May 21, 2018

A. Morning Nilesh, Hope you have already resolved your problem. I have had similar issues with copper strikes in the past. First, 48.5 g/L (6.4 oz/gal) seems a bit high for metal content. Not that I assume it is the cause of the discoloration. I'v always tried to keep copper between 2 and 3 oz/gal (14-23 G/L). The first time I experienced this deep red color in a KCN Cu strike it was due to drag in contamination from prior rinses. Check your bath for any contamination. if there is any suspicion I suggest changing any Swills or drag out baths prior to the strike. Once I saw this problem develop due to over temp as well. An operator bumped the heat control and pushed the temp way up. It was only noticed because the copper started to get a deep red tarnished color. What are you putting the copper over? Amps-dwell time? What is the potassium carbonate concentration? And what is the "Main" bath you mention? Also copper? Is the redness starting at the strike or after that "main" bath you mentioned?

chance dunstan
Chance Dunstan
Electroplating/Forming/Coating Manager
Placerville, California USA

Roughness in copper cyanide bath

July 25, 2018 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. We have had roughness on the high current density areas of our parts and on the hull cell plates. from what I can tell its not shelf roughness because its not just on the top surface of parts. the bath is a cupralite cyanide copper plating bath prepared with sodium copper cyanide solution and sodium cyanide. brightener additions are cupralite 10 and Cupralite 20
analysis as follows
copper metal: 5.03 oz/gal (spec 4-6)
free cyanide: 1.82 oz/gal (spec 1-2)
cupralite 20: 6 %v/v (spec 4-8)
total carbonates: 8.44 oz/gal (Spec nmt 10 oz/gal) far the bath has been carbon filtered with flow king pelletized in a carbon filter bag carbon to remove some organic impurities the filter was flushed to ensure that carbon doesn't contribute to particulates
2. the entire bath was decanted into totes through a 10 micron filter bag the tank was rinsed and cleaned then the anodes were returned to the bath and solution was returned to the bath through a fresh filter bag.
3. we were running very low on copper in the anodes a portion of copper was added to each anode
4. the anode bags are old we have new anode bags on the way to replace them.
i was thinking maybe the roughness was due to particulates in the bath but we still have the problem despite the bath decant and filtration. would any of you have another idea to try and fix the problem.

Caleb Archambault
plating chemist - detroit, Michigan,USA

Seeking alternative methods for lowering Copper Cyanide in Alkaline Bath

September 18, 2018

Q. We barrel plate lead cores with copper in a sodium cyanide and caustic bath. Our copper cyanide naturally rises over a period of time, and we have been experimenting replacing a few of our titanium baskets loaded with copper anodes with iron baskets loaded with iron anodes. We have found that our Copper Cyanide concentration is lowered and it raises the free cyanide. This practice does produce a desired outcome, but the drawback is the exponential increased production of Carbonates in the bath and an increase in Copper Oxide buildup on the iron baskets containing the iron anodes. Please advise if there are other methods to lowering the Copper Cyanide concentration without using iron. We are also seeking the pro's and Con's of using Iron in the baths at any point.

Bobby Farner
Shop Chemist - St George, Utah USA

July 13, 2019

Q. My copper cyanide bath is not catching plating. Please what to do?

jamiu ochawu
- kano state, nigeria

July 2019

A. Hi Jamiu. This could be absolutely anything from a defective rectifier to the parts that you're trying to plate actually being aluminum rather than zinc. Step 1 is probably plating a Hull Cell panel to narrow it down at least a little bit. Good luck.


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Aloha -- an idea worth spreading

Cyanide copper plating blisters

August 23, 2019

Q. Sir please tell me what is the reason of bubble in cyanide copper electroplating?
Sir, base is aluminum and first plating nickel then cyanide copper on this.

Amit Kumar
- Delhi, India

August 2019

A. Hi Amit. Have you burst these bubbles and examined them? Underneath the bubble on the substrate is bright shiny nickel, and the underside of the blisters is definitely copper?

This is an unusual plating sequence ... what kind of components are you making? And are you sure that you proceed from nickel plating directly to copper plating with no delay other than quick rinsing?


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Aloha -- an idea worth spreading

August 30, 2019

Q. I am using copper cyanide bath. The issue is that whenever I am plating mild screws, after nickel plating there are two shades in plating resulting, orange and red. I have added copper cyanide and caustic soda, heated the solution up to 30 °C but the result is same. The density is 12 and pH is 11.
Kindly help me out.

jazib khan
- karachi pakistan

February 26, 2020

Q. We are doing copper plating on iron rod in Barrel plating in Rochelle copper bath.
Bath concentration 20 g/ltr Cu metal
Free cyanide is 5 g/ltr.
When we start giving 6 VDC voltage my copper plate become black, and which results in black or patches type plating on wire rods.
I made new solution but the problem is still the same. Should I add some NaOh to solution?
Please help me.

Dheeresh sharma
- Jaipur, Rajastha,India

February 28, 2020

A. Hello Dheeresh,
The common Rochelle bath contains sodium potassium tartrate. You don't mention that in your bath makeup.

Mark Baker
Retired - Winston Salem, North Carolina USA

August 22, 2020

Q. Good afternoon sir,
I have cyanide copper plant and doing copper platting on ms plates. I am facing issue regarding quality of componants -- issues like black patch observed after plating, and uneven plating thickness. Please provide me solution for above.

Gajanan Kaldate
- Ahmednagar, Maharatra

this text gets replaced with bannerText
spacer gets replaced with bannerImages

Q, A, or Comment on THIS thread SEARCH for Threads about ... My Topic Not Found: Start NEW Thread

Disclaimer: It's not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental Compliance

©1995-2020, Inc., Pine Beach, NJ   -   About   -  Privacy Policy
How Google uses data when you visit this site.