Here are the facts: Kim has been firing to cone 10 with these posts in her Olympic updraft kiln for 15 years. Never a problem. (They were bought from Sheffield Pottery in western Mass. I've emailed Sheffield, but have had no response yet.) When she opened her kiln Thursday, one side of the stack was tilted ominously. Reaching the bottom layer, she found all three support posts tilted and splintered at the bottom, as you see in the photos.
It seems to us that if a prop was going to give way after 15 years it would happen one at a time. Or, perhaps, one in one part of the kiln and one in another. But all three on the same shelf strikes us both as a clue ... but a clue to what? We have no idea. Stacking was the same as usual, with heavier pots in the center of the stack, lighter ones to the outside.
It seemed an ordinary firing other than the collapsing posts. Any ideas? Let me know.