Age hardening is easily done. You hold the metal at about 600 deg in
your oven for, say, 2 hours, then turn the oven off, let it cool
overnight to room temperature, then you are done.
hardening of metals (well, copper, gold, silver) happens when there
is internal crystal structure growth. heating these metals to near
the melting temperature, then cooling quickly, prevents the crystal
growth formation, which makes the metal soft. heating it to about
550-600 deg and holding it there, then cooling slowly, lets the
crystal grow, and this makes i harder. for copper and silver, t his
will not be as hard as a hammered finish, but maybe about 70%? as
other metals (steel, aluminum, etc) work differently, for example
steel, cooling quickly makes it hard.