That reminds me of the time I was baking clay overnight and in the morning was shocked that the doorknob to the kiln room was hot. After I got in, the heat blasted me. The cone switch had malfunctioned and allowed the kiln to go to dangerous levels. All the clay in the kiln melted- yes, melted. The interior of the kiln was destroyed. I felt so fortunate that a major fire had not occured. The lesson is- even your back-up switch may malfunction. After that, I never cooked anything above low overnight again.
Subject: Re: ceramics - ages and emotions about breakage
From: "makul9" <firstname.lastname@example.org>
Date: Sun, 24 Apr 2005 12:06:03 -0500
I have fired hundreds of kids' ceramic pieces without a single explosion.
This is not because my students have made "perfect" constructions but
because I slowly bring my kiln up in temperature, especially in the early
stages of the firing. Most kiln instruction books assume that you are firing
thin, even slip molded ware which is very different than hand built or wheel
thrown works (especially beginner works). My firings are a minimum of 12
hours (to bisque cone 010) preferably I start the kiln on low (sometimes
just one switch) the night before firing. Another tip: ALWAYS, ALWAYS use a
cone in the peephole for visual observation as a backup for any automatic
shutoff systems (cone-sitters et al.) and check that the auto system has
functioned properly before leaving the kiln for the day (or overnight). All
of those systems wear out eventually and you will ruin all of the work in
the kiln as well as do damage to the kiln and kiln shelves when it overfires
significantly . Hope this helps!