Stephen,
We have on numerous occasions cooled our flasks down and reheated
them. In fact, when we used to cast medical product in stainless, we
actually had a fixed process that included a double burn-out cycle.
We did statistical studies that proved (at least on a particular part
geometry) that the double burn-out produced superior product. Go
figure? We never did get a handle on what was occurring on a
molecular level, but we did know it worked. Having said this, there
are a couple of caveats: we used phosphate based high temp investment
in combination with a ceramic shell system. Also, make sure that you
cool your flasks down to room temperature, if you try to speed up the
process by hitting say, 100 degrees centigrade and then cranking back
up, you will not have the same results. It’s just a question of
keeping nature happy with a smooth and gradual firing curve.
Teresa Frye
TechForm Advanced Casting Technology