Dennis did you spray or put something on the face? I have never seen a blow out in the middle of a blank like that. I know that hurts, out of 5 that I cast I will lose about 2. Most the time it is because I have gotten one of the parts too high and cut into it. Out of the 18 or so I have cast I haven't had a single blow out but I was using epoxy.
I am getting ready to cast my first Alumilite blanks kind of got me scared to now, after you already have so much time in them you hate to lose them.
Did your pour go normal. We're they gummy when they came out and you cooked them for awhile? Did you notice anything different in the turning before the blow out, more chippy than normal? Just trying to figure out what went wrong before I do it on mine.
Mike