1) Do not use nickel as some people are allergic to it.
2) Melt metals according to the highest melting point.
I don't really follow #2, I just pour all the metals with borax in
the crucible and melt them, once they have been fully melted
(alloyed), mix them.
1) It's not advisable to use nickel in jewellery, but there are
minimum allowances for it in Australia, 3% for external skin
contact, and 0.05% for piercing posts and other such pieces that
have intimate contact.
2) That's interesting, however I always load my crucibles with the
lowest meltpoint metal, as this reduces the heat required to melt
metals. For example when i make my bronze I always load my
crucibles with the tin first, then cover with granulated copper. The
copper crusts up and seals the crucible, the tin melts, and the
copper melts into the tin. One of my friends does the opposite, and
loses a lot of his tin as vapour, as he dumps his tin into the
Regards Charles A.