Chris, when I lived in Western Australia I loved cuttlefish casting.
I could get a bucketfull of good big pieces by taking a pleasant walk
along the beach. Now I'm in the UK, like you, I found it was rather
expensive to buy, compared to investment materials. Do you have a
cheap supply? I do find it very useful in some circumstances. Whilst
in Australia I ran short jewellery courses for the local arts and
crafts group and the final session was casting with cuttlefish, so
everyone got to use up all the bits of scrap arising from their
earlier sessions. So, a few thoughts:
You don't say just how the end results differ, but the real trick is
to get the temperature high enough, and keep it high while pouring.
The metal should appear to spin in the crucible, and it helps to keep
the flame on the metal whilst pouring. Make the sprue and funnel
quite large, in fact as large as you can, so that the metal gets in
Stand the mould upright on a metal tray with dry sand in it. This
inspires confidence when pouring, so that you can do it quickly and
Lightly soot the inside of the mould as the final step before
assembling it for pouring.
Dont't expect to get more than one casting from a mould. Sometimes
you can get more, but don't expect it.
Recycling sprue material is fine. The usual rule of thumb is to
have at least 50 percent new metal in the melt.
You can use bits of scrap sheet an wire, but casting grain is
cheaper to buy, and is specifically formulated for casting.
I achieved interesting results when casting pendants by lightly
brushing parts of the mould, after pressing and removing the pattern,
so as to bring out the grain structure of the cuttlefish. Works well
on backgrounds, leave highlight areas smooth of course.
Good luck, and have fun.
Kevin (NW England, UK)