Summary for chrome plating poor coverage Discussion
Chrome plating has poor coverage when the part is near maximum size, with chrome appearing only on high-density areas and seeming to plate in pulses. William Steever asked whether the issue was a power shortage or an anode problem, noting he uses lead anodes. Dennis replied that chrome plating is less than 20% efficient, so plating cannot occur without hydrogen gassing; that points to an electrical-side problem. He suggested checking whether the anodes near the unplated areas are making good contact, but said it sounds more like a rectifier problem, possibly one that is broken or simply undersized. Ted Mooney agreed that if the chrome solution shows pulsing, the rectifier may not be rectifying properly and could be passing some AC; he recommended having an electrician check it. He also advised checking the anodes for excessive contamination.
Q. Some times when I put chrome over a bright nickel I only get chrome on the high density areas. The part seems to be plating in pulses — it bubbles, then stops, then starts again. This usually happens when I reach the maximum size part I can do. Could this be a power shortage problem or an anode problem? I use lead plates for my anodes. Thanks.
William Steever
plating – Fredericton, N.B., Canada
2005
A. Hi William. Chrome plating is less than 20 percent efficient, which in turn means there is just no possibility of chrome plating occurring when there is no hydrogen gassing. So the problem is indeed on the electrical side. What color are the anodes in the vicinity of the areas that aren’t plating? It could be anodes that aren’t making good contact, but it sounds more like a rectifier problem … probably broken but maybe just not big enough.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
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2005
A. The last time I got that problem, it was an unknown rectifier defect that reduced the capacity; it wasn’t enough big or capable with big pieces.
We changed it and the problem was gone.
DANIEL HERNANDEZ GUERRA
– BUCARAMANGA, SANTANDER, COLOMBIA
2005
 | A. William, No.2, Check your anodes for too much contamination on them. Regards,
A. Check your connections at the anode and the rack to the bar and to the parts. Dirty connections prevent current flow, especially when they get hot. James Watts A. William Best of luck Qutub Saify |
Q. We are doing tri-layer nickel-chrome decorative plating and are depositing like 0.5 micron of chrome. Recently I had been observing lack of coverage in particular component. I was thinking it could be a problem with that particular component’s jig. But some other components are also found with same issue (no coverage in chrome). Kindly help me with this. Can you tell what are the factors I should check (and about jigs too). Thank you.
gibson A
– Chennai, Tamilnadu, India
October 19, 2012
A. Hi Gibson. I think the first thing to do is a Hull Cell ⇦ huh?
test, so you know whether the problem is the plating solution itself, or the electromechanical areas like the rectifier, anodes, and jigging. Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
October 22, 2012