Had this happen to me. I seemed to have plenty of heat on it–2
torches also. The student had gotten it to the slump stage (about a 2
oz. melt), but no further. With the addition of 2 torches, it
liquified, but didn’t ever real move like it usually does in the
liquidus state. Didn’t pour well, definitely didn’t mold well. Took it
home and used my husband’s big welding torch and rosebud on it. No
In class we were using propane/air, and then added a small
propane/oxy torch to it. I think what happened was it wasn’t enough
heat for the mass, especially after the slump. The heat couldn’t flow
around like it does with grain, because it was partially fused
already. When it got to the molten stage, there still wasn’t enough
heat to bring it up to the liquidus stage, so it froze.
My husband’s welding torch is acetyl/oxy and the rosebud tip was
probably overkill. But I was determined it was going to melt. It did,
and in very short order. So, it might be worthwhile to sweet talk a
friend with a more powerful torch to help you out, to at least get it back to grain.