I have collected a huge range of clays from various places that just won't stand stoneware temperatures. Some of these will only take an earthenware firing and others can be nudged up to midfire temperatures as long as the firing isn't too long. I've been trying to decide what to make with these and how exactly to fire them and finally made a decision over the summer.
Apart from a collapse it was an excellent firing and I began to see what reduction cooling can actually do. There was some wonderful colour variation, black carbon trapping, haloing around wads but most impressively a gorgeous lustrousness to many of the clays. Definitely a starting point for more experimentation.