Kiln Pointers from Paragon January 2002 – July 2009 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 [email protected] / www.paragonweb.com Copyright 2009, by Paragon Industries, L.P. 1 Low Voltage During the Summer CONTENTS Low Voltage During the Summer Recent Q&As: Memorable Quote News: Over-Temp for Digital Kilns ----------- LOW VOLTAGE DURING THE SUMMER Even a small drop in voltage can slow your kiln down. Here is an example from my own test firings: I test-fired a kiln recently. It took 5 hours and 3 minutes to reach 2331 degrees F (1277 C). In an earlier firing on a different circuit, the same test kiln took only 2 hours and 30 minutes to reach 2350 degrees F (1287 C). The difference in voltage between the two 120-volt circuits? Only seven volts. If your kiln is slowing down, do not assume that it is due to worn elements. The voltage to your building may be low due to summer time demand. If so, try firing your kiln when electrical demand is lower and the voltage is higher. Fire at night or early morning. ----------- RECENT Q&As Q. On the Sentry Xpress processor, why would you use a second segment, and what's the purpose of the speeds? A. The speeds are for simple firings that need only a single segment. For instance, you are firing to 1650, holding for a certain period, and then turning off the kiln. You would not need an extra segment for that type of firing. Each single speed, from 1 through 5, fires at a particular rate per hour. SPd1 fires at a rate of 200 degrees F per hour. If you wanted to fire to a single temperature at fast rate, you would use SPd5. The extra segments in PRO1 - PRO4 are for more complicated firings. You may never need more than one segment, though. In fact there is a tendency to use too many segments, especially with small projects. 2 If you were firing a thick glass project into a mold, you would need an extra segment for cooling through the annealing range. Otherwise the glass would crack, because it would cool too fast. Any time you want to change the firing speed or add an extra hold somewhere in the firing, you will need an extra segment. For instance, crystalline ceramic glazes need several segments. ----------- MEMORABLE QUOTE “Read an hour every day in your chosen field. This works out to about one book per week, 50 books per year, and will guarantee your success.” -- Brian Tracy ----------- NEWS: OVER-TEMP FOR DIGITAL KILNS We are offering an over-temp for digital kilns. It is the Orton Auto-Cone, a cone- activated shut-off. The retail price is $120.00 when installed on a new kiln. The Auto- Cone is independent of the controller and the thermocouple. ----------- Have you ever had sharks swim inches from your face? That happened to me last Saturday while visiting the Dallas World Aquarium with family. As we stood under a curved glass archway, the sharks swam past us on the other side of the glass. The glass archway is a marvel of design that any glass artist would appreciate. Sharks are exquisite. I could watch them for hours. I wish you a relaxing July 4th weekend. Clay Biscuits for Runny Ceramic Glazes CONTENTS Clay Biscuits For Runny Ceramic Glazes Recent Q&As: Four factors in choosing a kiln; viewing witness cones; witness cones and a digital controller; the small gouges in firebricks Memorable Quote 3 News: Basic Kiln Seminar October 2 – 3, 2009 ----------- CLAY BISCUITS FOR RUNNY CERAMIC GLAZES By Lili Krakowski What can you do about running glazes? TEST, TEST, TEST. Never put a new glaze on a pot before testing it first on test tiles of several clay bodies in several locations in your kiln. Never apply glaze from a new batch before testing it first. (Mixing errors are made!) Make pancakes or biscuits of grogged, quite refractory clay, and set tests on them. Not an itty-bitty biscuit, but one large enough to act as saucers. Designate a worn or uncleanable shelf TO TESTS ONLY. And for those who love double application, test that too. Oh, the messes created by one glaze over another, fluxing each other! Making Biscuits (Please see Lili’s accompanying drawing.) 1) Add grog, fireclay, or alumina to the high temperature clay. 2) Wedge the ingredient from #1 above into the clay. 3) Spread the clay into a “biscuit” about 1/4” thick. 4) The biscuit edges can be irregular, or you can make a pinched rim. The middle of the biscuit should be flat. Make the biscuit big enough to catch glaze sputters. Note: Biscuits work both ways: They protect a kiln shelf from glaze, and they protect pots from glaze that has embedded into a shelf. (Thanks, Lili, for the pointer on biscuits and for the drawing that you graciously included. --Arnold) ----------- RECENT Q&As Q. I am considering buying my first kiln. The choices and information on kilns seem overwhelming. 4 A. Choosing a kiln becomes simpler when you narrow the search with these four factors: 1) The size of the electric circuit in your studio. Will you use the circuit already wired, or will you have a new one installed? Your kiln choice will be limited by the number of amps available. 2) The size of the kiln. Estimate how much firing chamber space you need. How big are the pieces you will fire? How often do you want to fire? 3) Front loading or top loading. 4) Firing temperature. Narrow the kiln selection search with those four factors, and make a list of kiln models that you are considering. Then compare those kilns in greater detail. Try out the competing controllers using online interactive demos. That is like driving a car before you buy it. Q. I lose shelf space when I keep a clear line of sight from the peephole to the cones and the element behind them. (This question refers to positioning the witness cones inside the kiln.) A. You need to see only one set of witness cones. You don't have to see them on every shelf. Q. I'd like to add a hold on my digital controller to heal glaze pinholes in my next cone 5 firing. Should I fire to cone 4, add hold time, and stop the firing when I see the cone 5 witness cone drop? A. Yes. Fire to cone 4 with hold, and turn off the kiln when the cone 5 witness cone drops. Write down how long the kiln was on hold. Then the next time you fire, program that much hold time. Q. The firebricks in my kiln have what look like gouges, or small holes, on the surface. The depth of the holes is 4 – 8 mm (1/3 inch). Is there anything wrong with the kiln? A. Do not worry about the holes. A surface gouge with a 4-8 mm depth is normal for a firebrick. The bricks are porous. Those gouges were formed when the bricks were manufactured. Firebricks can withstand tremendous stresses during firing. They expand and contract; they cycle from red hot back down to room temperature repeatedly. Few other materials are put to such a severe test. Consequently, cracks and other cosmetic flaws form in the surface and are unavoidable. ------------- 5 Paragon’s website now has 581 FAQs. You can find answers to questions by entering key words in the search line at www.paragonweb.com. Example: A search for paper clay brings up this answer: http://www.paragonweb.com/faqinfo.cfm?faqid=618 ----------- MEMORABLE QUOTE “My grandmother, who has taught china painting for 60 years, coached me during my first firing. I treasure the memory of that moment of my life with her.” --Darcy Giesseman ----------- NEWS: BASIC KILN SEMINAR OCTOBER 2 – 3, 2009 Paragon will hold a 1-1/2 day Basic Repair and Maintenance Seminar at the Paragon kiln factory in Mesquite, Texas. The seminar covers basic electricity, kiln electrical installation, the multi-meter, switch replacement, electrical troubleshooting, element replacement, the Kiln Sitter, electronic kiln diagnostics, and more. Please call for more information. ----------- Last Saturday I was on the roof of my two-story house replacing the chimney siding. The sunscreen on my face looked like war paint. As I crouched on a scaffold, my safety glasses slid off the roof and into the back yard. The next day I retrieved the glasses. One of my dogs had neatly chewed off the stems, which were scattered in the grass. I hope you are enjoying your summer. Record Your Kiln’s History CONTENTS Record Your Kiln’s History Recent Q&As: Firing bronze clay; repairing a lid chain; FULL firing rate explained; worrisome error messages Memorable Quote 6 News: Safety Backup For Digital Kilns ----------- RECORD YOUR KILN’S HISTORY Keep a record of upgrades that you make to your kiln. This will prevent errors when ordering parts later. For example, a customer recently ordered heating elements for the lid of a Paragon glass kiln. According to the kiln’s serial number, the lid had the u-shaped groove that we discontinued several years ago. However, the customer had changed the lid to the newer recessed, pinless groove without telling us, so we sent the wrong elements. Examples of kiln upgrades: Changing the kiln’s voltage (i.e., from 240 to 208) because you moved to a different building or a different country Replacing the lid on your glass kiln with a lid that has a different groove type than the original Upgrading from a single relay to dual relays or a mercury relay Write the date and type of upgrade on your instruction manual or on a sheet of paper stapled to the inside cover.