Cadmium Plating Of The Stainless Steel Bolts
I have recently been asked to cadmium plate stainless steel bolts. Do you have a process that you can recommend?
Q: I have recently been asked to cadmium plate stainless steel bolts. We routinely cadmium plate but we have never had much success plating on stainless steel. Do you have a process that you can recommend? K. M.
A: There really is no magic involved when plating on stainless steel base materials! The first thing you must do is to prepare the surface so it is active (non-passive). There are a number of different steps that you can use to prepare the surface but the one that almost always is successful is to use a Wood’s nickel strike bath. The Wood’s nickel strike bath is a very active, aggressive bath that removes oxides from the surface and deposits an active nickel layer. A typical formulation for the Wood’s nickel bath is shown in Table below.
|Nickel (added as nickel chloride)||45 g/liter|
|Hydrochloric acid (conc)||10% (by volume)|
|Current density||10–40 ASF|
|Maximum nickel concentration||75 g/liter|
Of course, the surfaces should be thoroughly cleaned prior to use of the Wood’s nickel strike. After the strike step, the parts should be rinsed thoroughly and than plated in your cadmium plating line. The steps between the Wood’s nickel strike and cadmium plating should be rapid. Active nickel surfaces passivate rather quickly.
The reasons for installing an in-house cold blackening system are many and varied.
Why is it important for you to know this?
Our expert, Art Kushner, says yes, you can color stainless steel, but it is not a process that is typically performed in a plating shop. Read more about his answer.