I am using a programmable kiln for casting. It is a Paragon Express
E16T. My casting buddy and I did our investing the prescribed way,
mixing it thoroughly in the allotted time. We then invested using my
vacuum caster–twice, once in the bowl and once in the flasks. We had
a total of flasks, per load. The 9 hour burnout schedule we followed
was the one recommended by Swest. We checked the temperature
regularly, and it was precisely as we had programmed it.
After burning out at 300 degrees for 2 hours, I removed the wax tray
and found only a really small smidgen of wax. I was puzzled, as there
was nothing to pour out. We were casting sterling, fine silver, and
sterling deox. We had used Matt purple and blue carving waxes, and
the regular red sprue wax.
After the burnout was completed, we removed the flasks and were
surprised to find that the investment was all blackened. We had
understood that this was a sign of an incomplete burnout, but to our
relief, the casts all came out perfectly, no pitting, no porosity,
just perfect. Some of the wax models were heavy ones, others very
thin, yet they all cast perfectly.
When the kiln cooled down I examined the floor of the kiln, and it
was perfectly clean–no sign of dripping wax. Where did it go?
We did notice smoke exuding from the vent during the burnout, but
thought this was normal.
Is it normal for the wax tray to just have a smidgen of wax in it–
just a couple of drips?:
And, what about the blackish investment. Could it be that the wax
had vaporized and entered the investment? When doing the initial
burnout at 300 degrees, for two hours is it possible the wax had
melted sooner and had vaporized?
I have taken a number of classes in casting, but the instructor
always did the burnout, and so I never had a chance to learn first
hand what goes on during burnout.