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Kiln Pointers
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Converting Minutes to Rate Per Hour |
CONTENTS Converting Minutes to Rate Per Hour Recent Q&As: Firing a kiln window hotter than 1700F; an overheated wall outlet that didn’t trip the breaker; materials for element groove repair A Kiln Story: Five Gallons of Wasted Glaze News: Jackie Truty on Jewelry TV ----------- CONVERTING MINUTES TO RATE PER HOUR In a temperature controller, the amount that you raise or lower the temperature per minute or hour is called rate. Paragon’s controllers measure rate in degrees per hour. To raise the kiln’s temperature by 100 degrees in one hour, the rate is 100 degrees per hour. Instead of degrees per hour, some programs are written as minutes needed to raise or lower the temperature (i.e. raise the temperature from 540 to 675 in 30 minutes). Below are the steps needed to convert minutes to degrees per hour. Note: A segment has a rate, target temperature, and hold. Step 1) Subtract a heating segment's beginning temperature from the segment's target temperature. (Do the opposite with a cooling segment. Subtract the cooling segment's target temperature from its beginning temperature.) The segment 1 example shown below is a heating segment. 540 - 26 (room temperature) = 514 Step 2) Multiply the number of minutes needed to reach the segment's target temperature by .0166. Segment 1 example: 120 x .0166 = 1.99 (rounded off to 2) Step 3) Divide the number in step 1 by the number in step 2. Example: 514 divided by 2 = 257 The rate per hour in the segment 1 example = 257 degrees per hour. **Sample Program, Time in Minutes** Segment 1) time: 120 minutes; target temperature: 540C Segment 2) time: 30 minutes; target temperature: 675C Segment 3) time: 40 minutes; target temperature: 810C Segment 4) time: as fast as possible; target temperature 516C Segment 5) time: 60 minutes; target temperature: 427C Segment 6) time: 30 minutes; target temperature: 371C
**Sample Program Converted to Degrees Per Hour Rate** Segment 1) rate 257C; target temperature: 540C Segment 2) rate 270C; target temperature: 675C Segment 3) rate 204C; target temperature: 810C Segment 4) rate as fast as possible; target temperature 516C Segment 5) rate 89C; target temperature: 427C Segment 6) rate 112C; target temperature: 371C ----------- RECENT Q&As Q. I have a Paragon SC-2 with window. I am disappointed that because I have the window version, I cannot fire the kiln above 1700F even though it is a 2000F kiln. Does using the white fiber material that came with the kiln in the window allow higher degrees than 1700F? A. When we first started installing the glass window on kilns, we used a glass that was rated to 1700F. The glass window we are now using is rated to 2300F. So you can fire to 2000F. Place the ceramic fiber in the glass window cavity when you fire materials that do not need to be checked visually, such as metal clay. The window is convenient in firing glass and copper enameling. Q. My wall outlet and cord plug overheated and must be replaced. Why didn’t the circuit breaker shut off the power before the outlet overheated? A. The circuit breaker shuts off the power when the amount of amperage running through the wiring is too high. For instance, the breaker will shut off when it detects a short circuit. The breaker cannot detect a loose connection that causes a wall outlet to burn up unless the heat travels through the circuit to the breaker box. Q. Can kiln cement be used to hold an element in the groove of a glass fusing kiln instead of the more expensive Pyrolite that you sell? A. Pyrolite is an element adhesive that attaches the heating element directly to the groove. Please do not try that with kiln cement, which is used to glue broken pieces of firebrick. An element embedded in cement would burn out. ----------- A KILN STORY: FIVE GALLONS OF WASTED GLAZE Maggie Furtak of Malden, Massachusetts wrote, “I moved to a new group studio a few years back. A cheery new studio-mate suggested that we share some kilns. Sounded convenient. She loaded the first one and fired it. Eek! All my pots were monsters! They were supposed to be a high-gloss, bright blue but turned out dry, crusty greenish-gray. I had mixed a new batch of glaze when I moved in and assumed I must have measured wrong. I couldn't figure out any problems from my notes, so I threw out five gallons of glaze and mixed a new batch. Again, my studio-mate thoughtfully plucked some of my pots from the shelf to fill her kiln. More monsters. “It turned out she wasn't using witness cones,” wrote Maggie. “She was just relying on the Kiln Sitter to turn the kiln off, and the calibration wasn't right. The kiln was set to cone 6 but barely making it to cone 4. I usually fire to cone 5 1/2. Her pots all looked ‘fine’ because she'd always fired in that kiln and had never realized that there was a problem. She had probably tested a lot of cone 6 recipes that didn't work though! “After that I loaded my own,” continued Maggie, “and watched them through to the end, although I was always happy to put some of her pots in my kiln for her. “Use cones!” Maggie suggested. “I use three at each peephole for a glaze firing. I have a ‘degrees of cone bend’ picture chart taped to the wall by the kiln so that I can shut the kiln off at just the right time and so that I can record exactly what each cone, on each shelf, actually got to, along with my other firing data.” ----------- MEMORABLE QUOTE "If you can dream it, you can do it." --Walt Disney ----------- NEWS: JACKIE TRUTY ON JEWELRY TV On August 28th, Jewelry TV featured the SC-2 kiln in a four-hour segment. It was part of a presentation by metal clay teacher and author Jackie Truty. We believe the exposure on national TV will increase the awareness of kiln-fired jewelry. ----------- A few days after 9/11, my next-door neighbor, Tim, stopped me on my driveway. I wiped sweat from my brow and removed my bicycle helmet as he spoke. His face was red and not from the sun that glared down. Tim, who sold copiers, had visited the office of a client that day. He arrived to find office workers gathered around one of the employees. Some hugged her. She had just found out that her brother, a fireman, died in the Twin Towers. That was the only time that I ever saw Tim weep. Thank you, With best wishes, Arnold Howard Paragon Industries, L.P. – Better Designed Kilns 2011 South Town East Blvd., Mesquite, Texas 75149-1122 Voice: 972-288-7557 & 800-876-4328 / Fax: 972-222-0646 / ahoward@paragonweb.com / www.paragonweb.com / www.facebook.com/paragonkilns PRIVACY NOTICE: Under no circumstance do we share or sell your email address. Copyright 2011, by Paragon Industries, L.P. |
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