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Metal finishing Q&As since 1989
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Fouled Electropolishing Coil
Q. We're having difficulty maintaining temperature in our electropolishing tank so we removed the heating coil - a Teflon spaghetti type. It was plugged with a greenish crystalline material that was acting as an insulating layer preventing adequate heat exchange. My questions are: (1) what is the solid material (most likely a salt of nickel and/or chrome but which ones?) and (2) what's the easiest way to dissolve it without resorting to mechanical means (those tubes are delicate)?
Milt StevensonPlating Shop Engineer - Syracuse, New York
2007
A. Milt- please be more specific. What metal(s) are you electropolishing? What is your bath chemistry?
![Jon Barrows](../portraits/jon_barrows.jpg)
Jon Barrows, MSF, EHSSC
GOAD Company
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Independence, Missouri
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2007
Q. OK OK more info .... we're electropolishing traditional 300 series stainless steel and the electrolyte is a conventional heated phosphoric / sulfuric syrup!
Milt Stevenson, Jr.Plating Shop Engineer - Syracuse, New York
2007
2007
A. It might be a monobasic nickel phosphate salt. Something like Ni2H4(PO4)2. That's an educated guess.
Try some aqua ammonia. Some people call it "ammonium hydroxide."
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Dave Wichern
Consultant - The Bronx, New York
I had my environmental operations supervisor try Dave Wichern's ammonia
[on
eBay or
Amazon (adv.)] trick and he was pleasantly surprised - it seems to do the trick! Thanks Dave!
![milt stevenson jr.](../portraits/milt_stevenson.jpg)
Milt Stevenson, Jr.
Syracuse, New York
2007
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