How to get rid of star dusting
Q. Our bright nickel has what some platers call “star dusting.” It looks like very tiny particles plated into the nickel, not just on the shelves but also all over the surface. The parts are all buffed copper plated. How can we get rid of this?—O.P.
A. Star dusting is typically a type of pitting. The major difference between so-called star dusting and conventional pits is size. There are a number of possible causes of the star dusting you are seeing in your bright deposits. The table below gives some suggestions as to what you might do to solve the problem.
|Pitting Cause||Possible Solution|
|Iron content of bath high||
Remove by raising the pH with nickel carbonate, adding peroxide and filtering. Reacidify to operating pH.
|Anti-pitting agent is low||
Add additional ant-pitting agent. Check by measuring surface tension.
|pH of the bath is low||
You are plating out too much hydrogen. Raise the pH.
|Boric acid may be low||Check the concentration when tank is at operating temperature.|
|Suspended particulate matter||
Check your filters on the tank. You may need a finer filter.
|Organic impurities||You may have to treat with peroxide or activated carbon.|
Are you monitoring the plating solution with a Hull cell? If not you should. The Hull cell functions very much like a “canary in a coal mine.” Last but not least, check with your chemical vendor to find out if they have any suggestions to help solve your problem.