So, I had some other clever title in my mind when I went to sleep last night, but for the life of me I can’t remember what it was. It was something humorously ambiguous about the benefits (and losses) of getting really hot. This was not it….
Suffice it to say that I over fired my kiln. Again. I have just not started this run-in to the Holidays very well….
The first two “Oops!”s were me forgetting that I was even firing the kiln and suddenly realizing that I needed to check things. A bisque was okay after I came out and shut the lid about 400 degrees after I normally do, but my first glaze kiln of the season I completely forgot I was firing, and had to yank myself out of the kitchen when in the midst of pouring a cup of soymilk I realized I was supposed to be doing something. Doh! Turns out I had overshot my target temperature by about 50 degrees, and the much cooler bottom had not been given a chance to even out. Even with the lower melting glazes in the bottom only a handful came out alright, and the top three zones were just a bit hotter than I would have liked. Most survived okay. I use my least favorite pots in the first load anyway, so the risk was limited this firing….
The kiln I unloaded yesterday was not as lucky. This time I sat on it at all the crucial junctures of temp and got everything to where I thought it should be. “A perfect firing!” I thought. But it turns out the bottom was slow enough getting to temp that my stalling of the upper parts still dramatically over fired two glazes in particular. On the insides of pots one boiled. On the outside of pots they both ran…. Crap! That was about two dozen pots! A handful were able to get enough flattening with my bench grinder that I think they are alright (sort of), but many were not….
Its a good thing I use wads. Its a good thing I have drip edges along the bottom of the walls.
The blue glaze on those front cups is a new one for me and I haven’t figures out all its tolerances (obviously). In the previous round of firings I had left the bottom of the kiln unloaded and not worried too much about getting temp down there. My target temp (which I even played conservatively this time) had far less time spent hovering just below it. This time I was supposed to fire some pots for a friend in a glaze that could only be fired much cooler than the other glazes I use, so I had to try to get the bottom to at least a temp that those glazes would work. Turns out I sacrificed the rest of the kiln to do that….
Of course I could replace those bottom elements, but the ones in there are only about two dozen firings old. Way too early for them to crap out on me, I thought. They still look pretty good too. For the price of a new set of elements I could practically run the rest of my firings for the season without using that bottom zone to load pots in. I gotta think about this…..
At least my two test flasks (thrown as demos during class) were able to get resuscitated!
Gotta go check the kiln I’m firing now, so this is it for the present. Wish me luck!