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If a new lehr or kiln would make your decorating operation more competitive and profitable, but you can't afford new equipment, then it is time to seriously consider modernizing or improving the management of your existing equipment. If an old house can be economically remodeled and modernized, why can't the same be done with old kilns and lehrs?
Five relatively simple steps can help you economically achieve greater management and control of your firing processes:
1. Record all the temperature curves you are now using.
2. Document how each lehr or kiln was adjusted when you made the temperature recording(s).
3. Read what the temperature recordings tell you.
4. Do the obvious repairs now.
5. Work with a professional to investigate ways to upgrade and improve your older lehrs and kilns.
Each step in itself might appear to be very simple, but the full benefit can only be realized by performing each step fully and correctly.
Record Temperature Curves
Recording each of your current firing cycles or firing curves is the first step. This is analogous to what doctors do when they measure your blood pressure, temperature and perform a few other basic tests. While you record your firing curve, you should measure with several thermocouples in different places to determine uniformity within the kiln or lehr.
Once you have recorded your firing curve, analyze what it means. A typical recording may reveal abrupt heating or cooling or non-uniform temperatures that can help explain breakage or poorly fired ware. Figure 1 shows a recording of an old lehr done with two thermocouples, which reveals irregular heating in several places during the preheat.
Recordings of the firing cycles you commonly use should be documented and filed where they can be found easily. If you don't have these firing cycles recorded, you should do so immediately and store them in a notebook or file folder you maintain for each lehr or kiln.
Document Adjustments
The second step is to document the various settings or adjustments for each lehr or kiln while you make the temperature curve recording(s). To do this, it is helpful to devise a log sheet (see Figure 2). Typical data to keep track of includes the date, the identification of the lehr or...