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Nickel plating problem, dark and bright streaks

2002

Hello,

I have a Nickel bath made up by a person whom sells them to small companies like my self for in house use. We were plating small bolts and odd parts for automotive use and the system was working fine. We went from a 4 gallon system to a 12 gal. system. All of a sudden it plates out with dark and bright streaks as if some took nickel on a brush and just splashed it on the part.

We filtered out the tank and added more brightener still does not work. We plated out a dummy part of tin sheet bent into 1" 90* bends for 2 hours still has a problem. Any ideas?

Bill Dean
- Victor, New York

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First of two simultaneous responses

You do not give much information about your process. Is it barrel or rack processing; judging by your parts I suspect it is barrel. If it is barrel, is the volume of parts suitable for the size of barrel? No matter which system you use, are the electrical contacts good? Try doing a Hull Cell Test to see if the nickel bath is OK. Hull Cells are the quickest way to check your solution for performance. If the bath is faulty, I would suggest you dump it and start again. If it is the bath, you should find out why it has gone wrong. You do not say whether the problem began as soon as you increased the bath volume or if it began later. It could be due to drag-in from upstream solutions, such as cleaners or preplates. If it a preplate, you may well find a low current density plate-out done overnight will solve the problem, depending on the contaminant.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK

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Second of two simultaneous responses

Looks like skip plate to me, caused by excessive brightener. Carbon polish a little at a time until it works or carbon treat all the brightener out and then add the correct amount. You need to be very careful with the amount of brightener added in such a small tank, I usually add 1/4 the amount recommended then see what I get and add incrementally to get the desired results.

Russell Richter
- Danbury, Connecticut, USA
2002
2002

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This looks like a cleaning problem to me. Your parts need to be clean and active before going into the nickel bath. More brightener is not going to help.

Neil Bell
Red Sky Plating

Albuquerque, New Mexico

2002

How clean was the new tank? Did you leach in acid any fresh poly, welds, filters before adding the solution?

Kevin Keating
- Rochester, New York
2002

I have actually had this problem. In my case it was caused on a zinc based alloy. Spotty runny plating. Are your nuts and bolts zinc plated before going into the tank? That could be the problem. The zinc is being attacked but some plating is getting through. You will have to strip or plate in a cyanide/alkaline copper strike bath prior to nickel plating.

Tom Haltmeyer
- Peoria, Arizona, USA
2002

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Bill,

It looks like you have a lots of zinc and copper contamination in your nickel solution for me. Try dummy plating whit low current 0,4-0,5A /dm2. Try it also in a Hull cell there you can get a answer how for how long time you must dummy plate it.

Regards,

Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika,
Sweden
2002