Summary for acid zinc coverage problem Discussion
acid zinc coverage problem: the thread asks why parts of a single piece are not plating when using a hook in a 2500-liter acidic zinc bath. Ted Mooney, P.E. notes the issue as a non-coverage problem, and Amirhossein Ghanbarpour advises checking whether the acid zinc bath chemistry is within specification. He also recommends running a Hull cell panel to verify the bath’s throwing power and making sure the rack or hook contact is tight, since loose contact can prevent enough amperage from reaching the part. The practical focus is on electrical contact and bath condition rather than on the size of the tank itself. No conflicting advice appears in the excerpt; the guidance centers on confirming good contact and proper chemistry before looking elsewhere.
Q. Greetings and respect, we only plate one piece by plating an acidic plating in a 2500-liter bath. The problem is that when we use the hook for plating, parts of the pieces are not plated.
We solved this problem by wrapping the wire around the piece as is shown in the image. My question is what else can be done so that the wire is not needed. Because this is very low production method.
Amirhossein Ghanbarpour
production expert – Tehran
January 30, 2025
A. Hi Amirhossein,
You are apparently plating an assembly of parts rather than an individual casting or weldment. And the problem appears to be that electricity does not reliably flow from one part in this assembly to the other parts.
Electroplating occurs in proportion to current flow, and there is no way around that. If you must continue to electroplate after assembly (which is generally a poor idea), then you must continue to reliably bring electricity to each of the parts, and apparently you cannot rely on the current properly flowing from part to part through the assembly. It might be possible to design a plating rack which contacts the individual pieces as necessary.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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A. Amirhossein Ghanbarpour
Acid zinc coverage problem, check your chemistry parameter of zinc acid bath within spec.-run hull cell panel
make sure contact on rack tight if loose contact not enough amps go to part you plate
Popatbhai B. Patel
electroplating consultant – Roseville, Michigan
May 1, 2025