Why Plate Canadian Copper Cents

I have quite a few PM plated coins.

Why were they plated? I guess that they were plated for as many different reasons as I have plated coins. I certainly cannot provide an answer, except where I have been the culprit.

Here are five plated coins that I have:

Roman silver antoninianus of the usurper Emperor Postumus in EF. Gold plated.
Indian quarter anna 1898. Nice uncirculated. Gold plated.
Australian florin 1942 SF mint, EF. I had this one gold plated myself on a whim. I like it!
French 10 centimes 1853, fine. Probably zinc plated.
Guernsey one double 1893, EF. Nickel plated.

I once had a gold half sovereign gold plated to colour out the remains of a silvery looking mounting mark.

People gold plate pennies since it is a simple, easy way to test your plating baths. I have electroplating equipment.

Most commonly however is the gold colour is directly on top of the copper with no intermediate plating layer, it's not gold. What happened is they zinc plated the penny and heated it red hot thus forming a layer of gold looking brass. I believe that penny in the picture has been subjected to this.

If you really want to gold plate a penny, you pretty much have to plate it with nickel first. Real gold electroplating on copper just causes the copper to migrate into the gold and turn it a crappy colour, thus the need for a barrier layer.