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Nickel Leachate From Brass Tapware

letter: that is leaching out of tapware we plate. This nickel level is being tested as part of compliance requirements for tapware used with potable water. The levels we are trying to achieve are 0.02mg/l or less. The tests are run by having the required parts flushed with water for a period ranging from hours to days. Then the water is tested for nickel levels. If anyone can advise a way to minimise this nickel level or a change in process that may assist us in minimising it I would like to hear it.

Adam Degnan
a chrome factory - Sydney, NSW, Australia
2005

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The levels you are trying to achieve are very low; 20ppb is good going! I presume there is no nickel in the ater before it enters your taps, so you must be losing nickel from the tap. Have you checked the chromium level in the water as well? If ther eis no chromium, that would suggest the nickel is coming from areas where there is no chromium. If that is the case, you may need to to rejig your taps to get better chromium plating. If there is chromium there, you may have to thicken the chromium up to prevent the nickel being leached out. Alternatively, you can look for a substitute for nickel; try white bronzes - these are available from many international supply houses and this technology is being usd in the jewellery industry in Europe, where nickel is banned.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2005

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2005

Hello Adam

If the intention is to eliminate and reduce leachate and maintain a 0.02 ml/lit Nickel level, possibly the following may help.

- Plate electroless Nickel on the taps to start with. When tou have say 2 microns on, remove the part, and activate it in Hot sulfuric 10 % at 50 Centigrade, then plate at low cd in bright Nickel; for 3 to 5 minutes before ramping up gradually toachieving the required thickness and cosmetics.

If you were to plug the tap to prevent Deco Nickel solution from overplating the inner channels of the tap it would help with the leachate too.

Remove the plugs after bright Nickel..

Thereafter use a High throw Decorative Chrome bath to reach as far as possible and plate a minimum of 0.2 microns Chrome.

Electroless Nickel resists Hard water and slightly acidic media much better than the decorative nickels. Go for a medium phosphorous type say 7 % Phos.

Bright Deco Nickel deposits contain sulfur, are more active than Electroless Nickel and less resistant to corossion. ( read leaching )

Regards,

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016