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Electroplating and Voltage

I am in grade 7 and I did a project on electroplating. I tested at 1.5 volts 3 volts and 6 volts. what I found is that the quality of the electroplating went up as the voltage went up. but I also found as I put up the voltage the speed of which the process happaned was relativly the same. I was just wondering why this might be because it doesn't make sense to me.

Colton K.
student - Maple Ridge, BC, Canada
March 9, 2008

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First of two simultaneous responses -- March 14, 2008

Hi , the quality of the finish will depend on the current you use and the surface area of the part you are plating . current also depends on the type of plating you are doing i.e., - copper for example needs less power than chrome ....

If your plating improved as you put the power up , you started with too little -

If I was to be plating hard chrome , I would plate at 2 amps per square inch - if the part was 10 square inches , I would plate at 20 amps, etc.. I could plate at 3 sq" but the finish would become less attractive as it would start to burn at the high current density areas - top and bottom of the part.

So depending what plating you are doing , you need to establish the correct power . remember , lower is better , and you should be able to work out what you need by the appearance of the finishing . I cannot understand why there was no difference for you from 1.5 v - 6 v ? are you plating in a vat or by brush plating method ?

Jay Smith
- Essex, UK

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Second of two simultaneous responses --

Colton, you will find that the quality of the response is directly related to the quality of the information given. The metal being plated and the solution makes a light year of difference.
My guess, you had a relatively small anode and a relatively large anode to cathode distance.
What you found is opposite of reality in a commercial plating business as most plate will burn with the higher voltages. Solution temperature is also a factor in appearance.
The relatively same amount deposited at the different voltages is because of what is called the hydrogen overvoltage potential--IE: after a given voltage, hydrogen is given off at the anode so most of your current is going to forming hydrogen. Also, a little bit higher, oxygen starts coming off of the anode. Therefore, you are not using much of the available current for plating. Also, with long distances (relative) you will generate heat from the resistance of the solution.

James Watts
- Navarre, Florida
March 14, 2008