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White milky areas during Nickel plating

1999

Dear Reader,

We plate die-cast Zamak parts. (Copper Nickel -Watts bath-, and chrome). The problem we are having is that in (during) the Nickel bath white, milky areas appear on the surface. They look like the "classical" Chrome burn (Flash) but are not in the HDC areas. Another characteristic is that the spots are extremely smooth to the touch. Has anybody had similar problems and who could give me a clue as to what could cause these "misplates"?!

andreas gengenbach
- Venezuela

Hi Andreas ,

What you are describing is typical of an overdose of brightener , in the current systems each supplier has a "Corrector" for Organics , try this at their recommended concentrations , if it does not IMMEDIATELY fix the problem then the answer is too much "Trace Heavy Metals" and you will need to Dummy plate with corrugated cathode at a current density of 2 amps / square foot of cathode area .

Best regards

John Tenison - Woods
- Victoria Australia
1999

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Hi Andreas

I am assuming that the white, milky haze can be seen before chromium plating. We have seen this condition a couple of times lately and in every case, the plater had put new anode bags on his anodes. If you have changed your bags just prior to the condition occurring, this is probably the cause. Continuous carbon filtration is the corrective measure.

There are other conditions that can produce a milky haze and to expedite a solution, sending a sample to your supplier of additives is the best solution.

Regards

Ken Lemke
Burlington, Ontario, Canada
1999

Unfortunately, I'm afraid John is right, this has happened to me on more than one occasion and each time it was too much brightener. One time the problem was so bad that we had to filter the entire bath out and back in again using activated charcoal. This did remove all of the brightener and wetter.The key was white streaking out of the nickel bath prior to chrome, impurities typically were seen as dark in LCD areas.

Ward Barcafer, CEF
aerospace - Wichita, Kansas
1999