Homebrew PCBs

Stefan Trethan wrote:
> 
> Could the copper salt not be collected and given away as new etchant?
> I'm not sure it even needs neutralizing, CuCl dries to a green salt. Does  
> adding Na. make it less useful for further use? Could the HCl be reduced  
> by etching "until it stops"?

Evaporation will release the the free HCl and you should be left with 
hydrated CuCl2 crystals. I found it can take a while to dry.
The only purpose of neutralizing is for disposal. It never gets "used 
up", rather it slowly becomes a copper chloride etchant as opposed to 
pure HCl/H2O2 etchant. You still need to feed it HCl and H2O2 to keep it 
going, but HCl concentration doesn't become as important because the 
copper(II) ions are mostly doing the etching. H2O2 is like super 
effective aerating.

  What results when CuCl is burned?

For what happens when you heat CuCl2 see,
http://en.wikipedia.org/wiki/Copper(II)_chloride