More Blisters
We are plating Type 303 stainless steel with copper using a cyanide copper plating bath. After the completion of the cyanide plating step, we observe blisters on the surface of the parts. We use 5-gal tanks. What are we doing wrong?
Q. We are plating Type 303 stainless steel with copper using a cyanide copper plating bath. After the completion of the cyanide plating step, we observe blisters on the surface of the parts. We use 5-gal tanks. What are we doing wrong? I.C.
A.Your e-mail does not mention the process you are currently using to plate the Type 303 stainless., nor do you mention how the surface is prepared prior to plating.
It is a given that it is very difficult, if not impossible, to plate copper directly onto a stainless steel surface. Normally a Woods nickel strike is applied before the copper plating. There are many formulations for a Woods nickel strike. One such formulation is as follows:
| Component | Concentration |
| Nickel (as nickel chloride) | 6 oz/gal |
| Hydrochloric acid | 10% by volume |
| Anodes | Nickel |
| Control Factors | Range |
| Temperature, °F | 75–85 |
| Current density, ASF | 45–50 |
| Time, sec | 30–60 |
After applying the Woods Nickel, rinse quickly and thoroughly and immediately place in the cyanide copper plating bath.
Something else to consider: Using small plating tanks makes it very difficult to get consistent results. I recommend larger tanks, 25–50 gal, for the process. Larger tanks allow you to maintain temperature and chemical component concentrations more accurately.
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