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Topic #31721 "Nickel anodes turning black, black sludge in anode bags"

Topic #49000 "Nickel Anode Bag Problem (stiffness, covered with crystals)"

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Nickel plating anode bags: Cleaning, leaching, replacing, double-bagging, purpose, life

Q. We clean our Nickel anode bags with Nitric Acid. This removes Nickel Oxide and small Ni fragments. The problem is that the bags are remaining acidic after several rinses. Can we neutralize the remaining Nitric Acid with a Sodium Hydroxide solution or will we drag in Sodium and Nitrates into our Ni baths?

Doug Nash
- El Cajon, California

A. At what labor costs vs what bags cost, why waste the chemicals, time? Waste treatment costs would be about the same for the bags as the spent strip. One way to not cause too much of a problem would be to put them in a 5 gal bucket or a small tank, agitate very well, add 1N NaOH [affil link] until a ph meter read about 8, repeating until the pH remained above 7.

Your problem will not be with the acid affecting your nickel pH, the addition of nitrates is very bad for most nickel plating solutions. Why risk loosing a nickel tank, parts and customers to save a few pennies.

Talk to Jim's Plating Supply in Cincinnati for affordable bags. No relation, just a friend.

James Watts
- Navarre, Florida

Q. I am a novice at Nickel plating. On my first mandrels, I got nodules and "specs". What could have caused that? Also, how does one remove metal particles from the bath or to maintain the purity of the bath? Finally, if Ti is used at the anode, the provide contact for the Ni, will that present a problem eventually?

Razi Hassan
Alabama A&M University - Normal, Alabama

A. Nodules and specs may be that is foreign muck from anodes so pl. check for torn anode bags; if found replace it with new. And also check your filtration system that might be skipping carbon,.

Regarding metallic impurities you dummy the bath at 3.2 0.2 amps/Dm2. If brownish yellow to the walls of the tank or to anode bags it is due to Iron contamination so treat the bath at 5.2 pH with KMnO4 or with Hydrogen Peroxide. Nickel carbonate is used to raise the pH.

Panjala Mukesh
Panjala Mukesh
fashion jewelry mfgr.
Hyderabad, India

Purpose & importance of anode bags?

I am working on a small scale nickel electroforming process. The anode I am using is Nickel 290, a very pure Nickel. And by small scale I mean the anode I am using is 1" x 2" X 1/6". My question is about the use of anode bags, are they imperative? If I neglect to use one, will my platings suffer? What are the bags made out of? Can I make them myself? I only need a very small quantity of them, if I need them at all.

All your help would be much appreciated

Gregory Wahl
Clarkson University - Potsdam, New York

simultaneous replies

A. Any reason you are not using commercially available nickel anodes? The purpose of anode bags is to keep any metallic fines from entering the solution and plating onto the part. If they are not doing that, you can perhaps do without. Anode bags can be made of any material which is not harmed by the nickel plating solution. Woven polypropylene cloth is probably the most common material.

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

A. My first thought is you should be using a depolarized nickel rather than a "pure" nickel. The anode does not corrode properly to give you a near 100% anode efficiency and will cause you pH problems or at least require a lot more lab checking. Since plate rate is dependent on pH, you will have additional problems with determining a rate. Next, the internal stress varies with the pH as well as several other factors. Personally, I would buy 2 or 4 titanium mesh anode baskets and use SD nickel pellets that vary in size from buckshot to marbles. For electroforming, anode bags are nearly mandatory. Napped polypropylene cloth is the most common. Dynel is sometimes used, but normally for an inner bag in a double bag arrangement. Filtration is Mandatory for quality work. What are you using?

James Watts
- Navarre, Florida

Q. I am not using commercially available anodes because purity is very important to my research. Electrodeposition is a way to obtain a nanocrystalline structure in metals, and this is my area or research. I was under the impression that the anode bags were to collect the non nickel sediment in the depolarized anodes. My bath is only 1L. I'm making one sample per bath, and the sample is 1" long and about 1/4" in diameter. I was hoping this was small enough of a process that it wouldn't require bags or filtration. I have been researching forming for sometime now, and it has been hard to find much on such a small scale bath.

Gregory Wahl
Clarkson University - Potsdam, New York

Required Leaching Practice for Anode Bags and Filters

Q. With todays quality of anode bag material is it necessary to leach these prior to use in a sulfamate nickel plating bath? What might be the ramifications if you don't? Also, we use 1 micron filter bags for our EN filters, Same question on leaching.

Jerry Wendt
Manufacturing Engineer - Manitowoc, Wisconsin, USA
September 19, 2008

A. They might be just fine as is, but ... I once got in serious trouble using non-leached bags. It seems they were sewn with a silicone thread lubricant, which caused enormous problems in plating.

Wash them in hot water and detergent in a heavy duty washing machine. Twice.

jeffrey holmes
Jeffrey Holmes, CEF
Spartanburg, South Carolina

A. Jerry,
The best thing to do is to contact your anode bag manufacturer and ask them. Some of todays anode bags come "pre - laundered" with no leaching necessary. Some dynel or synel bags still contain sizing material which should be leached out with a 10% solution of sulfuric acid [affil link], then rinsed well. Again, see what the mfg. says.

Mark Baker
Process Engineer - Syracuse, New York

A. I agree with Jeffrey. Although manufacturers claim you don't need to leach the bags it does lead back to the old saying "an ounce of prevention....".

I generally suggest, for your application, leaching the bags in 5% by volume sulfuric acid for 24 hours. I would also add some of the wetting agent (anti pit) you may be using to this leach solution. Then water rinse throughly.
The reason for the use of the wetting agent is because of the tendency of the polypropylene to absorb some of the wetting agent from the solution.

Gene Packman
- Great Neck, New York

Why does nickel plating usually use double anode bags?

Why does Nickel plating use double anode bag? I think my inner bag is make of cotton and outer bag is PP. There is no info that explains the anode bags material choice in my company documents. Can someone help?

Sunshine Koh
plating engineer - SINGAPORE
June 14, 2009

simultaneous replies

A. Cotton won't hold up in a nickel solution, especially if sulfuric acid is used to control pH. Both bags should be of a plastic weave material. We used to used double bags to keep anode breakdown contaminants from getting back into the tank, causing roughness. Double bagging may not even be necessary if roughness isn't a problem...

George Brackett III
- Maine


Only reason to use double bags ( inner and outer ) double protection for roughness because during the plating create sludge at bottom of the baskets.if you use only one bag and bag touch with part or racks then tear off , roughness start on parts.

popat patel
Popatbhai B. Patel
electroplating consultant - Roseville, Michigan

A. Double bagging was used many years past and has been replaced by a combination napped polypropylene bag. Nickel anodes will produce very small fines that can cause roughness of the nickel deposit. A napped fabric (inside of the bag) is excellent for trapping these fines and prevent them from entering the plating solution.

Ask you supplier to provide a napped poly or canton flannel bag to replace your two bag system.

dayton dailey Dayton Dailey
- Lake Zurich, Illinois USA

Q. Please let me know what is the life of Polypropylene anode bags and what should be frequency to replace the same.
What defects will occur if anode bags are not working.

How can we judge anode bags life and not for use anymore?

Milind Markande
student - Aurangabad, Maharashtra, India
August 28, 2010

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