Reliable surface prep for high school Zn/Cu immersion plating lab

Letter 8091

Reliable surface prep for high school Zn/Cu immersion plating lab

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I am a high school chemistry teacher. Many years ago I worked at a plating house and have a vague recollection of the art of electroplating. We have a nifty little lab in the school where the students do zinc immersion plating on a penny (heated zinc chloride/zn solution). After the penny is removed from the bath, the students "wave" the penny over a flame and witness the mixing of the atoms as evidenced by the appearance of the characteristic brass color. Only problem is that some students get fabulous results while others are disappointed. We have tried old pennies and new pennies and consistancy is elusive. What I remember most about plating is that surface prep is everything.

Can anyone suggest a pretreatment routine that will improve my product to scrap ratio for these students. I recall that cleaners, etchants and rinses are routine chemicals. I do not need to pass any QA specs so exotic additives etc. are not necessary.

Thank you ever so much. The kids love! the lab but, as you can imagine, some feel it is more magic than electrons because of the unpreictable results.

Mindy Lekberg
Chelmsford High School - Chelmsford, Massachusetts

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