Cracked Chrome

Q. We have a problem with our hard chrome plate. A customer has stated that the hard chrome we are plating has “too many cracks” and the cracks are “too deep.” Where can we obtain additional information on how to control the cracking? R.V.

 

A. The number of cracks and the depth of cracks can be affected by a number of different factors. Some of these factors are: temperature of the plating bath, current density, solution composition, the amount of contamination, and the catalyst being used.

In my opinion, the best book on the subject is The Handbook of Hard Chromium Plating by Robert K. Guffie. Unfortunately, this book is out-of-print. You may be able to find a copy at www.amazon.com or one of the services that specialize in finding out-of-print and used books.

From the information included in your e-mail I would suggest that you look at possible metallic contamination in the plating bath. It may contain too much trivalent chromium or other “tramp” metals such as iron or copper. If the combined concentration of these metals is higher than 1.5 oz/gal, you may have problems. If trivalent chromium and “tramp” metal contamination is the problem, their concentration can be reduced by using a porous pot. Porous pots are commercially available. A Google search using the key word “porous pots” will give you information and the name of a vendor who supplies this item.