Metal finishing Q&As since 1989
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White stains in nickel plating of ABS
Q. I'm facing white stains, but my product is plastics-based, mainly ABS resin. The stains are detected at the high current area. Also the rejection only occurs on morning shift and none at night shift. We already tried a lot of troubleshooting such as reduced current, reduced temperature, increased brightener, extra wetting agent. We also did carbon treatment but still can't solve the problem. We detect it coming from our nickel bath because after we skipped plating for that tank the white stain didn't come. Can you give me a suggestion toward my situation.
Mal Az- Johor, Malaysia
May 8, 2019
May 2019
A. Hi Mal. The straight forward way to solve this problem seems to be to move your plater & foreman from night shift to morning shift because they seem to be operating the plating line in different fashion than the day shift :-)
It sounds to me like the day shift simply has the current set too high so the parts are burning, although you say you tried reducing it, but I suppose it's possible they are adding boric acid without dissolving it, or something like that. But again, the answer seems to be that your night shift plating team know how to plate :-)
Meanwhile please send pics to for posting here because there are so many different types of "white stains".
Thanks and good luck.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Thank You Mr Ted for the fast response. I don't really think the problem comes form our foreman because our company applies rotating shifts and even though the same person during night shift operate in day shift they also faced the the same problem. At first, we also suspected that the chemical not dissolving probably because they supply powder chemical about one hour before morning shift start. For that we try to dissolve first outside before supplying to tank. For another information, the White stain is only at the edge and milky white in colour.
- Johor, malaysia
May 10, 2019
A. Hi again. Apologies that I'm probably not understanding your pictures. On the non-computerized photograph I think I see a crescent moon shaped discoloration on the underside of the part 1/8" in from the left end, but the graphic on the computer screen is a greatly magnified view of the part, and the area of concern is only that very thin, very sharply curved narrow edge that the cursor arrow is pointed at?
Do you stockpile the molded parts before plating, or do they go almost immediately from molding to plating? If you do not stockpile them, is there a chance that there is something defective about the parts which you start plating in the morning (left over from the previous day, molding machines not fully warmed up, etc.)?
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
May 2019
Q. Actually the white stain I want to show you is not shown by the cursor but the long line. I upload the picture with red arrows for your review.
Now we adjusting again the brightener also the additive. Seems like the stain improves but only for a moment. Now the white stain already come on night shift but not in morning shift. Seems everything become inverted. We try to do the same thing we did on both shifts -- exactly the same. Parts come in also, same amount but it's not working. Now we already fall into a grey area.
Mal Az [returning]- Johor, Malaysia
May 17, 2019
A. Hi again, Mal. We'll have to see what others have to say, but those long almost straight lines at no particular place don't look like any plating defect I've seen. They look like scratches, or grooves in the mold :-)
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
May 2019
June 15, 2019
A. The white patch is referred to in Indian plating slang as "shadow" effect!
Check bath temperatures during both shifts, Plating Jig contacts, each and every process parameter.
Khozem Vahaanwala
Saify Ind
Bengaluru, India
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