Share 'Copper to Copper lab- switching from concentrated Nitric acid to 6M'

Flinn scientific catalog mentioned that one could switch from concentrated  to 6M nitric acid to oxidize copper in the first reaction of the copper to copper lab (aka sequence of chemical reactions, copper recycling) if one used their copper foil (0.005" thick).  In our original set up (conc. nitric + copper wire) the copper completely dissolved in 3 minutes.  When I tested the wire with 6M nitri…