The casserole lid

Yep, there it is, the lid tight as a drum on the base...except for the smallest one, where the lid was too small to correctly fit in the first place.

I was able to tap the medium size casserole to get it's lid off, but there were splinters of clay that fell off into the bowl, showing that I actually had broken some of the edge to get it open.  (I later took a Dremmel tool to it to make sure the edges all were smooth.)

The largest lid just wouldn't come off, so I followed the suggestion of our studio manager when I got home...that Marsha sometimes put it in the freezer.

But Marsha wasn't around the next morning when I took it out, so I didn't know exactly what the next step was.

So I let it sit an hour.  It didn't come right off.
I tried tapping it with the handle of something, which had that soft plastic handgrip on it.  No luck.  My taps became more frantic.  What was it going to take?

Finally it did come apart.  And again there were little flakes of stoneware which were inside the casserole.  They'd come off the edge of the lid, where it had been rounded, but also where it was touching the galley of the casserole lip.  There was plenty of give when I turned the lid around and around, though it sat best in just one place.

There was no glaze evident...these surfaces had been well waxed...and wiped.  But somehow the stoneware stuck to itself.  What makes that happen? 

The Dremmel tool again smoothed off the edges.  I don't make enough casseroles to know all the answers, but now want to know more about clay that adheres just by being fired to cone 6.