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Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing 1989-2024
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Chrome Plating Defect
Q. My customer rejected parts back to us for the dark spot in the chrome plating.
I am trying to work with our plating supplier but they said it wasn't their process causing this. Any help from the masses on possible root cause?
Hugo Ley- Aurora [California]
September 9, 2024
A. What is that brown item I see in the picture? Pictures admittedly can be deceiving.
Please wipe the spot with water to see if it is a water soluble stain like most plating stains, then with mineral spirits to see if it's a solvent soluble thing, and tell us what happens. Chrome stains do happen, but the color & texture just strikes me as a bit off for a chrome stain; maybe the plating shop does painting and got a spot of paint on it?
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. The line you are seeing is probably just a reflection. Either that or the weld seam from the tube. The spot in question looks like a burn mark. It doesn't come off with water or solvent. If this was zinc plating I would say it was where the electrode touches the part but I don't know if chrome plating is a similar process.
Hugo Ley [returning]- Aurora, Illinois
A. Hi again. Thanks for your patience! My mind immediately but wrongly saw a folding chair instead of a shadow on a tube :-)
A chrome plating does physically resemble a zinc plating operation, so the tubing hitting the anode is a theoretical possibility although I obviously haven't seen the chrome plating tank in question. Sorry, but I am not able to interpret the photo well enough to know which it is.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. I saw the picture, looks like peeling to me
from nickel layer to chrome, if you put one drop of copper sulphate solution on peel area and no copper color then peeling to nickel layer to chrome, on peel area, if it is copper color then peel from base metal.
if base metal peeler -- preclean problem or buffing material not come out.
nickel to chrome peel, nickel layer is oxidized
Electroplate consultant - Sterling Heights
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