Bobby copper II chloride leach or etching solution is made with HCl and 3% hydrogen peroxide (oxygen source air bubbled into solution is also used, this dissolves copper into solution to form copper II chloride, from here we can dissolve more copper but this will eventually form copper I chloride in solution changing the green solution brown as air and acid are consumed, and we will begin to see copper I chloride salts form (white powder at the bottom of the vessel), a little more HCl will convert the Copper I chloride to copper II chloride, air or dilute hydrogen peroxide will give us oxygen to help keep the copper oxidized in solution, ready to dissolve more copper.
If we use too strong of a hydrogen peroxide we will create chlorine gas in solution and dissolve gold, we do not wish to do this when our goal is to eliminate copper from the gold foils.
Bleach and HCl acid also generates chlorine gas in solution which dissolves gold.
Bobby the only way you are going to understand this is to spend the time studying, the older part of the forum went into long discussions on the process, and Laser Steve’s web site has a document on describing how the leach works and how to use it.
It is a very simple process once you understand it.
The only way to learn it is to spend time reading and studying,
Then once you understand the general principles, and then use them and observe the reactions.
Asking a million questions would only confuse you more with all of the different answers you would get.
Studying then asking a few questions when you run into a road block can help you understand the process.