"DoN. Nichols" wrote in message
...
Ouch! I don't think that is a good idea. I know that Plaster
of Paris has too much water, and when it gets hit by the molten metal it
explodes in steam, as well as loosing all strength as it loses the
water.

Nope! As long as it's dry and reasonably permeable, steam explosions aren't
a concern. I would imagine cracks form on contact allowing gas release.

Plaster of paris also maintains strength after dehydration, ask me how I
know- I've taken molds made with it it above 1000°F (dehydration temperature
of the hemihydrate) many times without it crumbling!

There are materials made specifically for the task. They are
baked dry as the wax is baked out with normal lost wax casting. I
believe that it is referred to as a "slip".

I don't know what commercial ceramic slurries are made of but it ain't slip.
Slip (as made from clay) shrinks on drying, exactly what you don't want to
use.

Note that a concrete floor will spall when hit with molten metal.

You should treat it as such, but when worse comes to worse, fortunately it
takes up to a minute before the aggregate gets up to boiling temperature and
starts raining metal on you. Enough time to spread some water on the spill
and cool it off.

You want a deep sand flooring if you have a choice.

Seconded!

Tim

--
"California is the breakfast state: fruits, nuts and flakes."
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