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topic 25248

Wood's Nickel Strike Bath Analysis & Maintenance



A discussion started in 2003 & continuing through 2017

One Wood's Nickel strike tank plates, the other doesn't

(2003)

Q. Hi,

I have a really puzzling problem. We recently set up a small Wood's Nickel strike bath. The size of the new bath is 106 liters, 30 x 70.5 x 60 cm deep. We were using a large bath 622 liters, 75.5x 90.5 x 101 cm deep. Both of the baths have the exact same concentration of nickel chloride (70 g/L) and hydrochloric acid (13 g/L). We are able to get plating in the large bath but are not able to get plating in the small bath using the same current density. The customer specifies that we use a maximum of 2.5 volts so we cannot increase the voltage. Can anyone tell me what I would need to do to plate in the small bath?

Thank you for your help. Best regards.

Aysun Scott
Metal Finishing - Kansas City, Missouri, USA


(2003)

A. If the solutions truly are the same, you should be able to prove it by plating Hull Cell panels from each; that would be the first step. Once it is established that the solution is not the problem, you may need to look at the geometry of the installation. 2.5 volts leaves very little for solution resistance and it could be that the shape of the parts precludes the operation from working at 2.5 volts. The resistance of your Wood's nickel bath is probably in the vicinity of 5 to 10 ohm-cm and you may find that the anode-cathode distance needs to be impossibly small to plate at 2-1/2 volts.

Trying running a calculation, because our intuition can be quite wrong depending on the specifics of the parts that are being plated. I was involved in an installation once where 18 volts wasn't enough for bright nickel plating--which we didn't find out until the line was built because it simply never occurred to any of a large team of highly experienced platers and consultants that it could possibly be a problem and nobody ran the solution resistance calculations :-(

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2003)

A. Considering that your small tank should have a closer anode to cathode spacing, I would have expected it to have done better. Based on that thought, I think that you have a line loss or connection loss. If it were mine, I would be checking voltage and amperage at every spot possible , right up to the parts and the anode. I would guess that your instruments are calibrated? Another thought is that you piggybacked it after the large strike tank and you are having some kind of losses to that tank. 2.5 volts is a really small voltage for a Wood's tank unless the part is tiny.

Tell us some more of your setup and what you have checked. This is interesting.

James Watts
- Navarre, Florida


(2003)

A. 70 gr/l of nickel chloride and 13 of HCl seems too low to me. I would give it a try with a higher concentration of both (up to the more common 250 gr/l each). This will increase the conductivity of your solution and improve the operation at low voltages.

Guillermo Marrufo
Monterrey, NL, Mexico


(2003)

Q. Thank you for your responses. We did check voltage and current. Isolated the anodes. Used different power supplies even replaced the anodes thinking the anodes may be passivated. We even tried dummying tank at low current to get rid of potential contaminants. We did not do a Hull Cell. We are in the process of doing a Hull Cell to compare the two tanks. In the meantime, we suspected that the wrong acid might have been accidentally added to the tank so sent a sample to the lab for analysis. It turns out we have .06% sulfates in the tank. Sulfuric acid and hydrochloric acid come in identical containers so someone probably accidentally picked up the wrong container. Will sulfates cause the bath not to plate?

Aysun Scott [returning]
- Kansas City, Missouri, USA


(2003)

thumbs up signThe problem is solved. Made up a new bath and the parts plate OK. It had to be the sulfates in the bath. Thank you all for your help.

Best regards,

Aysun Scott [returning]
Plating Operations - Kansas City, Missouri


(2003)

A. A simple test for sulfates is to get a beaker of bath and mix in a little Barium Carbonate. Sulfate will precipitate out. If you have a Chrome plating operation your lab probably has some Barium carbonate around along with an old Kocour Graduated centrifuge to measure its concentration.

Dave Kinghorn
Dave Kinghorn
Chemical Engineer
SUNNYvale, California




To minimize searching and offer multiple viewpoints, we combined multiple threads into the dialog you're viewing. Please forgive any resultant repetition.



Maintenance of Wood's Nickel Strike Bath

(2007)

Q. Does anyone have any suggestions for maintenance control for a Wood's Nickel bath ?

Dickie Martin
Engineering - Laurens, South Carolina


(2007)

A. If you are NOT using the tank everyday, remove the anodes and set them in a tank of water and cover the tank. If you are using the tank only once in a while, also remove the anode bars and store dry - also cover the tank.
When you go to use the tank, top up the tank to just slightly below the full mark to allow for the anode displacement, stir well and analyze 2-4 hours later. Make additions as required, stir well and analyze the tank 2-4 hours later.
Copper buss bars dripping into the tank from condensation is probably a major cause of tank pollution.
Nickel growth is probably the biggest problem after drag in that you will have with a Wood's tank. They last for years with occasional filtering and dilution.

James Watts
- Navarre, Florida


(2007)

A. The last time I was in your plant you used s-rounds in a Nickel Chloride Strike. That will work, for a few days, then because of the activity of that kind of anode (easy dissolving), you build metal rapidly and the inefficient "strike" becomes an efficient "plating" bath, now it will not activate that burned on fired nickel on your ceramic.

Start with bagged Rolled Depolarized NIckel bars, take out when not in use; when the metal climbs, use bagged carbon anodes until the metal comes down. Be aware that insoluble anodes cause emission of deadly chorine gas, so be careful.

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina

Editor's note: Mr. Probert is the author of Aluminum How-To / Aluminio El Como



(2007)

A. First, remove the anodes when the bath is not in use.

Second, do regular partial dumps of the solution to control nickel content. Because the anode efficiency of the Wood's Strike is greater than 100%, Ni builds up and there's really no way to stop it, that I know of.

Some oxidation reaction needs to happen at the anode surface, and the other ones that can occur are oxidation of chloride to chlorine (no fun to breathe) or oxidation of water to oxygen. Perhaps some one else knows of an inert anode that will only do the second ... I do not.

dave wichern
Dave Wichern
Consultant - The Bronx, New York


(2007)

Q. We use Rolled oval de-polarized anodes in bags. We only have the anodes in the tank when using the bath. We only use DI water to maintain the tank level. I am interested in what parameters, tank analysis and tolerances should be used to maintain the bath. The bath make-up is 139 L Nickel Chloride Solution, 59 L 31.5% HCl & 218 L DI water.

Thanks,

Dickie Martin [returning]
- Laurens, South Carolina



Woods Nickel bath analysis

November 27, 2009

Hi,

Can anyone suggest the bath analysis for Wood's Nickel bath for Nickel chloride as well as Hydrochloric acid content?

Thanks in advance.

Biren Desai
Plating shop employee - Bangalore, India


The Chemical Analysis of Electroplating Solutions

December 1, 2009

A. Any plating lab book will give you this. Analyze for nickel. Convert metallic nickel value to nickel chloride with the appropriate factor.
Analyze for total chloride. Subtract the chloride content from the nickel chloride value from the total chloride and you will get the HCl value. A simple way that should be satisfactory is to titrate for the acid with an organic indicator at about pH 3.5 and do it slowly with a dilute caustic so that you do not precipitate any of the nickel.
For a poor value, you can convert pH to HCl content.

James Watts
- Navarre, Florida


May 21, 2014 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. I will be obliged if anybody will give a procedure to estimate acid content of Ni-strike bath

Veerendra Singh Modi
- Indore,M.P.India



October 27, 2017

Q. Hi.
I have a problem with Wood's Nickel Strike bath; my bath loses the capacity to plate. Some months ago we were working normally, we didn't plate very many components. Nowadays we plate more, and we've changed the solution two times in six months.
We changed the solution and we found some black particles in the bottom of the tank.
Someone can help me?
Or someone has had the same problem?
Thanks.

Gustavo Mendoza
Universidad Tecnologica de Queretaro - Santiago de Queretaro, Mexico


November 2017

A. Hi Gustavo. I suspect that a component fell off of the plating rack and was allowed to dissolve in the bottom of the tank, consuming your acid.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


November 9, 2017

thumbs up sign I'm going to analyze the particles to know if it was a component that fell off in the tank, or what is the reason.

Thank you so much!

Gustavo Mendoza Melendez [returning]
Universidad Tecnologica de Queretaro - Santiago de Queretaro, Mexico


November 10, 2017

A. The most common problem is that by leaving the anodes in the tank when not in use, the metal content increases. A strike is supposed to be an inefficient low metal high conductivity solution. If you leave the anodes in continually, it change to a high efficiency PLATING solution, opposite for activation, Make a new solution and take the anodes out when not in use. Also S-Rounds dissolve too fast for a strike, no, use Rolled Depolarized Oval Bars

robert probert
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina



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