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Ted Mooney, P.E. RET
Pine Beach, NJ
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What is bipolar effect and its significance in electroplating?
We are using Cyanide Silver plating in barrel application. Pure Silver bars are used in Titanium baskets as anodes. Anode baskets are covered by PP bags.
We have found Silver deposit at the bottom of the anode baskets inside and continue to plate during production.
The anode and cathode connections are verified and found okay.
Also did not find any fallen parts at the bottom which makes the short of anode with cathode or at the close vicinity.
Please suggest what could be the reasons and how to control the anodes getting electrodeposition of Silver.
employee in electroplating company - Bangalore, India
December 3, 2021
A. Hi KMM. You may have more information than I can gather from the photo, but I don't see a reason to assume that this is an electrodeposit. Small metal fines will often fall to the bottom of an anode basket as the anodes dissolve, and silver can probably also mechanically rub off from the anodes onto the titanium surface.
As long as you have anode bags to contain those fines I don't think there is a problem.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. Titanium anode baskets ANODiZE (read insulate) in an alkaline solution, so there is no current in the bottom of the basket, the top is still barely bare and passes some current, as Ted says, the fines have fallen into the bottom of the, now insulated, bottom of the titanium basket.
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
⇩ Related postings, oldest first ⇩
Q. What is bipolar effect and its significance in electroplating?
VISHAL DUSE- INDIA
October 21, 2011
A. Hi, Vishal.
This refers to the fact that a metal item in an electrified tank forms a shortcut between the anode and cathode because it is more conductive than the liquid solution. As a result of that, the end nearer to the cathode becomes anodic and the end nearer the anode becomes cathodic. A useful example is that you can actually make an auxiliary anode for plating inside an item without any electrical connection: put one end near the anodes, and that end will become cathodic, the other end will become anodic and serve as the auxiliary anode.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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No- No Ted's got it all wrong ... - Orlando, Florida, USA
Sorry, I missed the boat. I thought the fellow was asking about the well-known "Bip'-o-lar" Effect, which happens to be spelled the same way. You know, where the electrons go ticking along "bip, bip, bip ..." Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey |
You're absolutely correct, Tim. "bi-Pōl'-ar". Of course!
Q. I have three Nickel Plating tanks all 12 feet long. Parts from two are chrome plated perfectly. Parts from third tank have burning in Chrome Plating (Around 50% Parts). After full investigation, we have reached the conclusion that the jig coming out of tank has bipolar effect. If we keep jigs apart from each other (by skipping one jig at alternate position) the bipolar effect is reduced. Almost no problem at all. The moment we complete the jigs the problem starts.
Please suggest some remedy.
- Lahore, Pakistan
September 5, 2013
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