FrogBlog
How to Load a Kiln
Loading a large kiln can often be intimidating. After talking with our friends at Paragon Kilns, here are answers to some of their most frequently asked questions... Do you recommend 3 or 4 posts under a shelf? It is recommended to support shelves with three posts instead of four. Sometimes four posts can cause the shelves to wobble unless the bottom of the kiln is perfectly even, the shelves are flat, and the posts are exactly the same height. It is best to position posts fairly close to the kiln walls and away from the center of the kiln bottom. This places the weight of the kiln load close to the kiln stand and away from the unsupported kiln center. How do you load the top shelf so that the ware fires to the correct temperature? On top-loading kilns, placing a shelf too close to the top of the firing chamber can lead to over- or under-firing. To help combat this, try using two half shelves, instead of a full shelf, stagger the height of the shelves. Another option is to mount the top shelf low enough so that element grooves show between the kiln lid and top shelf. How does one prevent posts from sticking to the kiln shelves? When you unload a shelf out of the kiln after a firing, a post occasionally sticks to the shelf and then drops onto the shelf below. To help prevent this from happening, dip the ends of the posts about 1/8” – 1/4” in a mixture of kiln wash. Only a thin coat is needed. How important is placement of posts inside a kiln? When possible, posts should line up vertically from one shelf to another throughout the kiln, especially with large kilns and heavy loads. Vertically aligned posts increase the stability of the load and reduce stress on the shelves. Do you need to fire a top-loading ceramic kiln with an empty shelf in the top of the kiln? It is not required but, a shelf placed in the top of the kiln will prevent brick particles from falling onto glazed ware. This is also useful if the lid is cracked. Some people like to place a shelf in the top of the kiln to prevent the incoming air of a downdraft vent from affecting glazed ware. Keep in mind, it would be better to fire the kiln without the blank top shelf, since the shelf uses up more electricity. What kind of gloves can you wear to handle kiln shelves? You can find thin, leather-lined mechanic’s gloves at home improvement centers, or try batting gloves! They are both thin enough for you to load and remove shelves inside a kiln. They will also help to protect your hands against sharp bits of glaze or glass. Always wait until the shelves have cooled before removing them from the kiln. Is it okay to continue using cracked kiln shelves? You should not fire cracked shelves. They could break during a firing and ruin a load of ware by causing other shelves to collapse. Is there a way to repair a broken kiln shelf? Unfortunately, there is no way to repair a broken kiln shelf. However, all is not lost, as you can still use the shelf pieces. Use a tile saw to slice the shelf into horizontal sections. Place broken shelf pieces under pottery that is decorated with runny glazes or pieces that have too much glaze. If the bottom of your kiln is uneven, place the broken shelf pieces in the bottom of your kiln to support posts. Use the shelf pieces as smaller shelves to place around tall pieces. Silver clay and enameling: Place hot pieces onto the broken shelf. It is a good fireproof surface. Lay the broken shelf across two half-shelves for even support of a piece with a large base. Is it okay to fire freshly coated shelves with a glaze or bisque load? No problem! When loading a kiln for bisque firing, just allow the shelves to dry beforehand. What is the difference between loading ceramics in a front-loading kiln and a top-loading kiln? Smaller, lighter pieces are usually loaded in the front of the kiln near the door or on the bottom. This is because these are the cooler areas of the front-loading kiln. Load heavier pieces near the back wall of a front-loading kiln as that is where they will get more heat. The cooler areas of the top-loading kiln are usually the bottom and sometimes the top so, load lighter, smaller pieces in those areas. Explore our selection of Shelf kits in various sizes and shapes by clicking here!
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Firing a Kiln in Cold Weather
From the bomb cyclone that many experienced last week to colder than average temps across Texas, this unusual winter weather sweeping across North America is causing havoc for everyone! So, with snow swirling outside and the wind howling, this question frequently comes to mind... can you fire a kiln in an unheated basement, shed or garage? A few years ago, Arnold Howard from Paragon told us about a customer who tried to fire a digital kiln in a garage where the temperature was 30°F. The digital controller display locked at 32 degrees, and she could not clear it. After the weather warmed up, the kiln started working again. Most digital controllers can register temperatures of –300°F; however, the circuit boards are designed to operate in temperatures no colder than 32°F. Temperatures lower than that can cause the controllers to malfunction. For example, the TCR message ordinarily means the thermocouple leads are reversed, but it can also appear when the thermocouple inside the kiln is much colder than the controller circuit board. In spite of this, it's definitely possible to store and fire a kiln in an unheated building in cold or freezing weather. Gail had her larger kilns in the garage for years prior to building her new studio. For storage, you must make an extra effort to keep moisture, such as the air from a dryer vent, away from the kiln to avoid the formation of frost on the metal jacket. When it comes to firing, it's important to first raise the room or ambient temperature to 32°F. This can easily be done with am inexpensive space heater. Just place it within a couple of feet of the control panel before you start your kiln and let it run for an hour or so. After you turn on the kiln and it begins to heat, you can turn off the space heater. Moisture that the firebricks have absorbed from humidity will burn off harmlessly so long as the kiln is vented. Keep the lid in the vented position until steam no longer fogs a mirror, or run a motorized downdraft vent. Look at the Orton Ventmaster 120V or Orton Ventmaster 240V on Kiln Frog. Stay Warm!
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Kiln and Oven Troubleshooting
Happy New Year ! After reading dozens of "I am so excited for my new kiln" posts, I thought I would share some Kiln and Oven Troubleshooting advice that I got from our friends at Evenheat Kilns. Brick Cracking and Hairline Cracks Hairline cracks are common in all kilns and should not be a concern. Bricks expand and contract when heated and then cooled. The cracks will close as the kiln gets hotter. This is most prevalent in the kiln top or bottom. Kilns fired at the higher temperatures will experience more spalling and cracking of the brick. Kilns cooled down too rapidly will effect the amount of cracking. If you are repairing a broken brick, repair cement should be used to adhere the broken piece back into place. If a brick breaks under an element and is impossible to repair, an element pin can be used under the coil to prevent drooping. Fuse "Blows" or Breaker Trips Immediately when Kiln is Turned On Generally speaking, if a fuse "blows" or circuit breaker trips immediately upon applying power to the kiln, or pressing the start keys, it indicates a short circuit within the kiln itself. It's also possible that the fuses or breakers protecting the circuit are not sized properly. Check the wiring for any signs of arcing (visual and smell). If there is any evidence of arcing, call a qualified electrician to fix the problem. This must be fixed before you continue firing. Another cause of this issue, is that the electrical service to the kiln is wired incorrectly. Have a qualified electrician check the electrical service from the main service to the kiln. There have been incidences where the connections from the electrical pole outside to the main service at the house has been loose. Finally, it could be as simple as the circuit is overloaded. The easy remedy to this is just disconnect all other appliances on that circuit while operating your kiln. Fuse "Blows" or Breaker Trips During Firing Generally speaking, if a fuse "blows" or circuit breaker trips sometime after the beginning of the firing it indicates a problem with the electrical service itself. The causes are varied. Heat at the fuses or breakers will cause them to "blow" or trip at lower amperage levels. This heat can be caused by a weak or loose connection at the fuse or breaker or elsewhere in the service (heat travels well in copper). A fuse or breaker is not normally warm or hot. It should be very close to room temperature during normal operation. It's possible also that the fuses or breakers are bad, weak, junk etc. Replace only with the proper size. Do not install larger fuses or breakers to solve this problem. Something out of the ordinary made the originals fail. The problem must be corrected not bullied into submission. It doesn't work that way. In this type of situation, it is suggested that a qualified electrician be asked to check for circuit problems. Be Smart. Be Careful. Have Fun!
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The Importance of Keeping a Firing Log
In 1905 Spanish philosopher George Santayana wrote these well-known words “Those who cannot remember the past are condemned to repeat it.” And, for anyone that uses a kiln on a regular basis that quote can have significant meaning. That is why we recommend that EVERYONE keep a kiln firing sheet or project log. We cannot stress this enough as it is the easiest ways to learn about your kiln and recall exactly what glass, metals, materials, molds, and most importantly, firing schedule you used. Over time, a properly kept log is critical to keeping track of what you’ve done. It will help you learn the particulars of your kiln plus it will go a long way towards avoiding future mistakes. In many ways, a firing or project log is the most underappreciated tool in your studio. All too often, the enthusiasm to fire overcomes the need to keep records of the firing, resulting in unusable comments. This is an enormous mistake. The firing or project log is one of the most essential tools you have. The combination of your kiln, the materials you select, and the designs you create are exclusive to you. No one else can precisely duplicate the conditions in your kiln, so it’s up to you to keep records that are detailed enough to allow you to repeat good firings and avoid repeating bad ones. Some people suggest that a printed log like the Bullseye Kiln-Glass Project Notes, or the Joy of Fusing Project Log, while others favor a simple notebook. Digital logs are also a popular option. It really doesn't matter which log you chose as long as you document, document, document! Some firings will require minimal notes while others might demand several paragraphs, pictures and/or sketches. Most importantly, keep you log in your work area. Use it religiously and enter essential information about each firing. As you become more knowledgeable, you may find that many of your firings are similar and require minimal entries. But regardless of your experience level, don't stop logging your firings, as your log is a priceless tool! Check out some of our best-selling glass kilns: Evenheat Studio Pro 17 Jen-Ken Vitri Barrel Vitrigraph Kiln Olympic 126 Lite
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Increasing the Life of your Firebrick Kiln
Throughout the years, we have seen 10+ year old kilns with firebricks that are still in pristine condition and relatively new kilns that looked like they had been dropped from a three-story roof. It's pretty easy to tell when a kiln has been cared for and given that extra level of TLC or, what we like to call "KLC"... Kiln Loving Care! Here are a few tips from Arnold Howard at Paragon Industries on how to give your firebrick kiln that extra Kiln Loving Care: 1. Vaccuuming is a must. Vacuum the kiln interior regularly using the soft brush nozzle of a vacuum cleaner. Be sure to vacuum the element grooves, the inner surface of the kiln lid or roof, and the underside of kiln shelves and be gentle when you touch the firebricks with the nozzle. Vacuuming the grooves is essential if you have had anything explode inside the kiln. Pieces of greenware that lodge inside the grooves can burn out an element. Vacuum the kiln often if you use silica sand on the shelves. The sand, which is used to support ware during firing, can ruin the elements if it filters down into an element groove. As you vacuum the kiln, examine the walls for glass or glaze particles that have embedded into the firebricks. Dig these out carefully. Otherwise the particles will embed deeper into the firebrick during the next firing. 2. Kiln Wash is your friend. Apply kiln wash, liquid kiln coating or glass separator to the kiln’s firebrick bottom. But keep kiln wash away from the walls and elements. On Kiln Frog you can find kiln wash for glass and kiln wash for ceramic. 3. Dry your greenware. If possible, do not fire moist greenware. It should be bone-dry and warm to the touch. If you must fire moist greenware, wait until all signs of vapor have disappeared before heating past 200 degrees F. The moisture at higher temperatures is not good for the firebricks and can cause the greenware to explode. 4. Be gentle. Lower the kiln lid (or close the kiln door) gently. Slamming the lid can crack the lid the first time it happens. Fully disengage the lid support before lowering the lid. Forcing the lid downward can break the bricks near the lid hinge. From time to time, check the condition of the lid support. 5. Keep closed. Keep the lid closed when you are not using the kiln. This keeps dust out and prevents the lid from dropping while you are away from the kiln. Do not store anything inside the kiln. 6. Level it. The kiln stand should be level and rock-steady. An unleveled stand can stress the firebricks. A stand that rocks can cause the kiln to move when jarred, knocking over ware against the sidewalls inside the kiln. 7. Don't lean on me. Do not lean too heavily against the firebrick walls while loading and unloading. Some people use a small stepladder to reach into a deep kiln. You can also cut a piece of plywood to fit across the wall that helps protect the wall during loading. 8. Try not to touch. During loading and unloading, do not touch the sidewalls of the kiln with anything. Do not allow a shelf to bump into the firebricks. The extra time and care you spend loading and unloading may add years of life to your kiln. 9. Always look for drips. If glaze, glass, or other materials drip onto a kiln wall or the kiln bottom, repair before the next firing. Otherwise these materials will remelt and embed deeper into the firebricks. Remove the contaminant by scraping gently with a putty knife. If you remove kiln wash from the kiln bottom, apply a fresh coat to the bare spot. 10. Don't worry! Do not be concerned about small cracks that appear in the firebricks. The cracks are normal and act as expansion joints. During firing, they close tightly. Finally, if a firebrick edge breaks off, don’t stress. The damage is usually slight and does not affect the firings, and can easily be repaired with our Firebrick Kiln Repair Kit.
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Kiln Repair Directory
We all know, life happens... and, usually it's timing stinks! You know how to fix the minor issues with your kiln but, sometimes after troubleshooting, you still need additional help. If repairs keep adding up, it may be time to repair or replace the kiln. Not to worry... Kiln Frog's "Kiln Repair Directory" is a great resource of over one hundred kiln repair technicians across the US.Please be advised that Kiln Frog does not recommend or endorse any of the named repair services and cannot be held responsible for any of the work performed. As kiln technicians are independent business people, it is also possible that their advice may not always reflect our opinion.Finally, to ensure that our list is as complete as possible, we are requesting your help! If you are aware of a good repair person or company, please let us know and we are happy to add them to our list.
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Learning to Read your Relay
No matter what kind of kiln or oven you use, unless you have mercury or solid state relays, it's a fact of life that relays need to be changed. But, before you replace the mechanical relay of a digital kiln, it is very important that you learn how to read the relay label printed on the side to be sure you are installing the correct one. The label is confusing until you spend a little time studying it. On the label, find the voltage of the relay coil, which is the electromagnet inside the relay. When the electromagnet receives a signal from the controller, terminals inside the relay come together. The terminals make a clicking noise and turn on the heating elements. The voltage of the coil is printed on the relay near a symbol of the coil. In the sample relays shown, the coil is symbolized by a rectangle with a diagonal line. The coil in the top left relay is 12 volts DC, which is the most commonly used kiln relay. The coil in the bottom left relay is 240 volts AC. The coil in the relay on the right is 200 - 240 volts AC (for 208 volt kilns). The 12 volt DC coil is used in relays that are turned on by a digital controller. The 240 volt AC coil is used for relays that are activated by an infinite control switch instead of a digital controller. DC means direct current, which comes from the controller to the relays. The symbol for DC is a horizontal solid line over a broken line. AC is the current from the wall outlet and is symbolized by a wavy line. The relay is rated for a level of current. The current rating of the relay does not mean it requires that much current to operate but, is the maximum safe level that the relay can handle.
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