The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Help with porosity of sulphamate bath

Hello, my family has a small company treating pieces with nickel sulphamate. The bath is small in a container of 25 liters, 600 g/l nickel sulphamate, 35 g/l nickel chloride and 10 g/l boric acid. The PH is 4,0 to 4,2. The temperature is of 54°C. Problems: after the processing of 30 pieces they appear pores, pitting. Is that some contamination of the process? How can I make an analysis to identify which the impurity?

Thank you very much,

Glenda Vaz
little company, hobby - Manaus, AM, Brasil
2004

---

First of two simultaneous responses -- 2004

A sulfamate bath needs an anti pit. Most of us in the industry will refer to it as one of the originals proprietary name of SNAP - Sulfamate Nickel Anti Pit. There is one formulation for mild mechanical agitation and another for air/mechanical agitation. Both need to be controlled or it will cause other problems.

The addition of an air agitation sparger will help a great deal also. This must be oil free air. A large fish tank air source may work. Remember that this solution is about twice as heavy as water so it will take a larger pump than for a same size fish tank. Do not use the air rock that comes with the pump. If it is not ceramic, it will dissolve. You can put small holes in vinyl tubing with a hot paper clip or piece of wire.

You should also have filtration on your tank. There are a couple of companies that make in tank filter pumps which are less of a spill problem, but take up tank space.

How are you heating the tank. High current electric heaters or gas heaters can cause the sulfamate to break down (160F) which causes several other problems.

James Watts
- Navarre, Florida

---

Second of two simultaneous responses --

Please give details of what you are plating (i.e., the substrate) and what your cleaning process is. No-one can help you unless they know what you are doing.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2004