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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
Student/Educational Electroplating -- Why Sugar?
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Q. Hi,
I am a high school science teacher with a chemistry BS. Sadly, all things electrical were not my strong point in college. I tended more towards analytical chemistry.
I do have one question. I was in need of some magnets (I already had the magnets) that were plated in a conductive metal. Your FAQ student directions gave me some excellent options (that turned in to a lesson of their own). I understand the use of the acetic acid
⇦ this on
eBay
or
Amazon [affil links] (vinegar) and the salt to make an electrolyte since it is only 5% acetic acid . But why the sugar? Does it reduce the conductivity enough so that the amount of metal coming out of solution is less than the amount going in? I've tried to look it up in my old college textbooks, but they are less than helpful. Perhaps you can explain?
Teacher - Chapel Hill, North Carolina
2006
A. Hi Jennifer,
The principal or theory is the hope that the sugar will act as a "plating brightener".
When doing electroplating, the plated metal will tend to grow as rather large crystals and stalagmites, which results in softness, porosity of the plating (holes between the crystals), and lack of brightness. Certain organic materials (brighteners) are used in electroplating because they are attracted to the spots where the plating reaction is concentrating, and tend to shield it from plating, disrupting the crystal growth -- causing the formation of more and smaller crystals or adatoms for a denser, harder, brighter, more corrosion resistant plating. Some brighteners may also function on a macro scale in addition to the micro scale, i.e., they may help achieve more even plating thickness across the part by shielding the areas of higher current where thicker plating would otherwise occur.
Sugar is far from an optimum brightener, and vinegar
⇦in bulk on
eBay
or
Amazon [affil links] is such a weak acid that classroom electroplating will be very thin anyway, so I don't know if the sugar can actually achieve much in this case -- but it's there both for the theory, and in case a student wants to try to test whether it actually achieves anything.
Good luck
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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