Ron...I have not used any of Don's CDs but have used some of his
site info in helping students get started in casting. I have been
steam casting, as he demonstrates, for nearly 25 years with great
success. I have better (and more expensive) equipment now but still
demo steam casting and 'how to do it on the cheap' to each class.
Re casting natural items....remember, these are organic. That means
carbon! So, you need more heat and lots more time. Be careful, some
investments begin to break down as you get up above 1300 deg. So I
normally burn naturals at 1250 to 1300 for 8 to 10 hours and turn off
the oven. Let it cool and then do another burn at same temp.
Depending on the item, whether its thick or thin, solid, heavy or
light, you might even consider 3 burns. Another thing to remember,
use a thin coat of some spray lacquor before investing. This seals
the surfaces and precludes the investment from infiltrating which can
cause carbon to stick to the inside surfaces thereby inhibiting metal
Try above and see how it goes. Cheers from Don in SOFL.