Hazy Decorative Chrome
Q. When I plate larger parts, such as restoring auto bumpers, the parts appear to have a hazy finish, particularly in the central portions of the part. I do not have this problem when I plate smaller racked parts. What is going on? —J.B.
A. What you are observing is often called “whitewash.” This can be caused by a number of different things. Since you mentioned that the problem seems to appear only with larger parts, I think the cause is change in the current density and temperature of the plating bath when the part is placed in the bath.
It is important that the part be at or near the temperature of the plating bath. The current density should be adjusted to compensate for the larger surface area of the part. You should also investigate how electrical contact is made with the part. For example, in a part like a bumper, you may require more than a single electrical contact.
There are a number of good articles on whitewash at pfonline.com. Use the search term “whitewash.”
A primer on this inexpensive and highly efficient process.
Types of anodizing, processes, equipment selection and tank construction.
An overview of precious metal electroplating processes.