electroplating apparatus gets very warm

Flyingwing12

I have a 12V 10A power supply connected to the copper electrodes used for making copper sulfate.

After about 5 minutes, the mixture gets warm.

An ammeter connected in series only shows about .2A of current being drawn so I suspect that it is the huge restiveness of the acid,water mixture.

Also, do I always need pure, clean copper to get a good plating?

I was able to wire brush some pliers and just dunk them in the solution and got a wonderful result.

Is there any way to get this automatic adhesion with any metal?

I am fairly new to this electroplating. I have piddled in the past but want to use the rust preventative properties.

chemisttree

Pure plating solutions give the best results. The type of plating you performed with your pliers is called immersion plating and is self regulating. You only can plate very thin coatings and it stops. Electrode coating allows you to build up much thicker coatings of better quality. Immersion coating only occurs if the substrate is of higher potential than copper so it can't be done with every metal.
You could do something called electroless coating which can be performed on any conductive substrate. Here is a good writeup.