Q. We zinc plate many batches of parts each day. Some of these batches come out dull after the plating and chemical conversion steps. Could this be caused by the base material? P.B.
A. There are a multiple of possible causes for dull appearing zinc plate. The cause of this dullness depends on the type of zinc plating bath. The following table gives some of the possible causes for a dull plate. (SEE CHART TO THE RIGHT)
In order to better determine what the cause of your particular problem is, more information is required. As you can see from the above table, causes of dullness will vary depending on the type of bath.
It is important to keep in mind that problems with the process steps can also cause the dullness.
An example would be if your rectifier had a momentary failure while plating some of the batches of parts. Also, operator error can cause problems of this type.
If you want to learn more about the ins and outs of zinc plating, I highly recommend Zinc Plating by Herb Geduld. The book is available from Amazon.com.
One additional comment: This particular e-mail does not contain very much information. Hence I am unable to give you a more detailed response to your question. It is always a good idea to include as much information as possible when sending me an e-mail regarding any plating problem. That way you will get a more specific response from me.