plating, anodizing, & finishing Q&As since 1989
Emissions control from bright nickel plating?
Q. Has anyone tried using a wetting agent or fume suppressant in bright nickel plating? The emission factors are tight and will be getting tighter. If suppressants work for hard chrome, why not nickel? Our tanks use the Watts process at 150 °F and are air-agitated. We make nickel screens for the textile printing industry and there is no substitute for nickel.Rick Alexander
- engravers - Gaffney, South Carolina
A. Rick, most nickel plating baths require wetting agents for successful plating, so that their surface tension is already way down in the range of 35 dyne-cm.
Chrome plating is extremely "inefficient", 12% to 25%, meaning that 75% to 88% of the applied electricity generates hydrogen bubbles (which rise to the surface and entrain plating solution). Nickel plating is way more efficient, producing little hydrogen. Also, the Chrome is in hexavalent form whereas Nickel is in divalent form, meaning that three times as much electricity must be used to deposit an atom of Chrome compared to an atom of nickel, even after discounting the huge difference in efficiency.
In most cases there are almost no emissions to speak of from nickel plating except for steam. Have you ever been able to detect any nickel mists in the air? For this reason, nickel plating tanks have often been unventilated; but steam/water vapor can make a mess too, so it's becoming commonplace to add local exhaust ventilation to nickel plating tanks, and then you have no concerns about either nickel mists or water vapor.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
What Ted said is correct.
You might well be getting, due to the bath temperature, some visible mists in winter time. But I doubt that they are injurious.
However, if you want to clear them up, if you are concerned about the appearance of any emissions, it sure seems that a very ordinary relatively low cost (& low S.P) blade type horizontal mist eliminator would do the job.
A good one, still not expensive, should take out all the mist down to 12 microns. If you want to 'improve' the collection efficiency, you could constantly spray water.
If you wish, give me your parameters........
Freeman Newton [deceased]
R.I.P. old friend (It is our sad duty to
advise that Freeman passed away 4/21/12)
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