The changes: Seasons, materials, firing schedule, glaze thickness. Few things stay just the same in a pottery studio. And the changes don't ever seem to happen one thing at a time. Neither do they happen when it's convenient.
Now that Custer Feldspar is no longer what it had been for so many years, and the substitutions appear to be fleeting, trying to get the same results from different materials is a challenge. But I'm getting close. I'm finally getting my green glaze close to what it had been. In fact, the new appearance is really nice in its own way.
This kiln load was hard-fought, though. I've made some adjustments to the kiln to alleviate a long-annoying hot-spot. As I failed to take that into consideration, the effect of cone 10 going down didn't really mean the same thing as it did with that annoying hot-spot warming the blind side of my kiln (I have peep holes in one side only).
Because I failed to consider that cooler cone 10, when I opened the kiln on Monday, all the green was gunmetal gray. I pulled out the old cones, set a couple of new sets on the still hot floor of the kiln (that way if they were going to blow, they'd do so right away and I could clean them out and start over). Once I was sure the cones were going to survive, I shut the door and simply refired the whole darn load.
It came out perfect. Best green glaze in over a year.
I hope I learned enough from that firing to skip that extra step double firing.