Firing the Large Platter

One of my readers came up with this question and I realized there was something I had forgotten. It's been so long.

It's true that one needs to stilt the green ware of that long, large platter for firing to bisque.

The reason is this. More than half the piece, is bottom. Considering its size, that means something. Your green ware must be able to move and slide or it will break. Because of its weight and the wide span of the bottom (foot) its much easier for the piece to drag hard across the shelf, not giving it enough breathing room for shrinkage.

Add to that, the fact that there is much more trapped air under the piece. Many times, just due to the weight of the center part, pulling it out of the mold will warp the foot just enough to weaken it. For that reason alone, you need to take special care in how it sits on the kiln shelf.

I've stacked as many as 3 of these platters for the bisque firing but if I forgot to stilt the bottom piece and place stones between, I'd say I averaged a good 30% breakage.

I would also advise, laying small posts on their sides, just under the lip to the platter about every 4" just to insure the lip doesn't sag and crack the bottom portion. It may be overly cautious but it sure will be worth the effort.

The glaze firing, of course, is a different matter as the clay has already shrunk.