|Monthly Tech-Tip |
These terra cotta clay bars were fired at cone 1. They have curled. That is ususual. It is happening because cone 1 is within the volatile firing range of this clay. Over a narrow range from cone 01-2 it shrinks drastically. These bars were fired on edge and the shelf heat-sunk the lower side, enabling the upper sections to get ahead (and shrink more, curling the bars). This is why this temperature would be avoided. Ware would warp. But at cone 02 it is stable. And at cone 2 it is also better. And vitreous.
A type of red firing pottery. Terra cotta clay is available almost everywhere, it is fired at low temperatures. But quality is deceptively difficult to achieve.