How to Choose an Electric Kiln
The kiln you choose must be rated hot enough for the ware that you will fire:
2350°F: Porcelain and stoneware
2300° - 2000°F: Low-fire ceramics
1400° - 1700°F: China painting, glass fusing, glass slumping, enameling, bead annealing
It is a good idea to buy a kiln that will fire hotter than you need it to. If you are firing glass to 1500°F, buy a kiln rated to 1700°F. If you fire ceramics to cone 6, buy a cone 10 kiln. As heating elements age, they draw less and less power. Generally, the higher the kiln’s maximum temperature rating, the longer the elements last. This is because even after the elements begin to wear, they still draw enough amperage to fire the ware. Another advantage to higher temperature capacity is that during periods of low voltage, your kiln will still likely reach the temperature you need.
In general, the larger the kiln, the lower the cost per cubic foot of interior space. Divide a kiln price by its cubic feet, and you’ll see what I mean. Will you want to fire many small loads or a few large ones? Some people prefer to fire frequent small loads to see how special effects turn out before spending time on other projects. Others prefer firing fewer large loads. This may be another factor in choosing kiln size. Choose a kiln that will fire the largest ware that you produce, and decide how often you want to fire the kiln. Figure how long it will take you to make enough ware to fill a kiln of a given size. Do you think your needs will expand later? Kiln owners will typically tell you to buy more capacity than you currently need, because you’ll probably outgrow your kiln later. Before purchasing a 10- or 12-sided top-loading kiln, visit a studio that has one. Reach down inside the kiln to be sure you are tall enough to load it. This is important. I know people who cannot touch the floor of their kiln, so they leave a shelf supported by posts in the bottom. If you have difficulty loading a studio kiln, consider the short and wide 12-sided, 22” deep kilns. If you fire ware of a particular size such as tiles or bowls, plan the kiln load on paper. Draw diagrams of different sized kiln shelves and determine how many pieces of ware will fit onto each shelf. You may find that the ware fires most efficiently in a particular size kiln. For instance, the 10- and 12-sided kilns can both fire 10 in. bowls. But since both kilns fire four bowls per shelf, the bowls fire more efficiently in the 10-sided kiln than in the 12-sided. The 10-sided kiln is also a good choice for those who need short firing cycles. Since 10-sided kilns are smaller than 12-sided, they can heat and cool faster. In addition, kiln shelves for 10-sided kilns are lighter than those for 12-sided kilns and are easier to lift.
Will you need a new circuit installed for your kiln? This may affect your choice of kilns. Only a licensed electrician should install a new circuit. Use copper wiring, not aluminum. Homes in the U.S. and Canada usually receive 120/240 volts. If your studio is in a business district, strip mall, or school, it is likely that your voltage is 208, not 240. It is important that you know your voltage before ordering the kiln. 208 volt and 240 volt circuits use the same wall outlets, so you can’t visually tell them apart. Call your power company or electrician if you are not sure about your voltage or phase. If you fire a 240 volt kiln on a 208 volt circuit, the kiln will fire slowly and may never reach maximum temperature. This is an expensive mistake, because you will need to order new elements of the correct voltage and possibly have the switch box rewired. Contrary to logic, 240 volt kilns do not necessarily fire hotter or faster than 120 volt kilns. Some 120 volt kilns can reach 1000° F. in five minutes!
4) Round or Square
On a per-cubic-foot basis, the “round” kilns (6-, 7-, 8-, 10- and 12-sided) are less expensive than the square because they are easier to build. Ceramists usually buy the round models while schools and potters sometimes buy the large square kilns, because they are especially durable and slow cooling.
5) Top- or Front-loading
Front-loading kilns are preferred for enameling, where pieces are removed from the kiln at 1450° F. This would be difficult with a top-loading kiln since the heat rises when you open the lid. Ceramists typically use the small front loaders for glaze testing and small pieces. Large front-loading studio kilns are easier to load than top-loading models because you don’t have to bend down into the kiln.
6) Firebrick or Ceramic Fiber
Though ceramic fiber heats and cools faster, insulated firebrick (used in most kilns) outlasts ceramic fiber. So each material has its advantages. In addition, heating elements are easy to replace in a firebrick kiln, because they are exposed in firebrick grooves. Most ceramic fiber kilns use elements embedded into the ceramic fiber. Therefore, these elements cannot be replaced. Instead, the ceramic fiber firing chamber and elements are replaced as a single unit.
7) Insulating Firebrick Wall Thickness
Most ceramic kiln walls are either 2½” or 3” thick. Kilns with 3" walls and lid take slightly less energy to fire due to the extra insulation. However, their main advantage is that they reach a higher temperature than their 2½” counterparts. They also cool more slowly, which is important when firing heavy pieces prone to cracking and for special glaze effects. To fire stoneware or porcelain, buy a kiln with walls at least 3” thick.
8) Manual or Automatic
Most manual-fire kilns operate with infinite control switches, the type used on electric ranges. They contain a bi-metallic timer that cycles on and off. As you turn the switch clockwise, the heating elements stay on longer and longer. On High, the elements stay on continuously. Manual-fire kilns are gradually being replaced by automatic models. If you are planning on a manual-fire because that is what you are accustomed to, at least consider an automatic kiln. Once you understand them, automatic kilns are easier to use than manual kilns. Before making your final decision, ask your dealer to demonstrate an automatic kiln for you. Automatic kilns are of two general types: mechanical and digital. Mechanical automatics use timers to advance the switch settings and the Dawson Kiln Sitter to turn the kiln off. Digital kilns use an electronic controller. Some people think mechanical kilns are more reliable than digital kilns. It is true that the wiring of a digital kiln is more complicated than that of most manual-fire kilns. Digital kilns use a transformer and relays, which are often not needed in a mechanical kiln. However, digital kilns are reliable if designed properly. Ceramists have been firing them successfully for over two decades. Digital kilns are also easier to repair than some people think. The heart of the system is a small circuit board that, in a well-designed kiln, can be removed in minutes and repaired or replaced. The biggest mistake kiln operators make is assuming that an automatic kiln will shut off as it should every time. Every automatic kiln needs human monitoring, especially near the shut-off time. So even though the kiln you are buying is automatic, plan to be near it at the end of firing. If the kiln takes longer than expected, look through the peephole at the pyrometric cones on the shelf. The cones will warn you if the kiln has fired to maturity and should be shut off manually. Once you begin to understand the reasons for so many different types of kilns, choosing the best one for you will be easy.
8) What about the plug?
While some smaller kilns only require a standard 120-volt outlet, kilns come with a variety of different plugs depending on the model, so it's vital that you know which outlet you'll need to install. We have a NEMA Guide to help you identify the different plugs and outlets that are available.
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So I bought a kiln… Now what?
A guide to The Ceramic Shop’s kiln purchasing policies and procedures
How long will it take to get my kiln?
All kiln manufacturers make kilns to order, which means they will make your kiln specifically for you, to your specifications. This means if you have ordered a kiln online, you will be charged at that time, although your kiln will take anywhere from 2 to 6 weeks to build. Please note that most kilns are constructed closer to the 4-week time table; please take your studio needs into consideration when preparing to buy a kiln! Because lead times vary by manufacturer, don't hesitate to give us a call for a more accurate estimate.
Occasionally, we do have smaller test kilns and sometimes even larger models in stock – in those cases, we can ship directly to you as soon as possible. When your kiln is complete and has been shipped, The Ceramic Shop or the kiln manufacturer will contact you. Please be ready for it on arrival! If you have ordered a kiln and haven’t heard from us, that doesn’t mean that we haven’t processed your order. Because the turn-around can take up to 4 weeks, we do our best to process all kiln orders within 24 hours of receiving them.
What do I need for the arrival of my kiln?
Well, you need to be available most importantly. Either The Ceramic Shop or your kiln manufacturer will be in touch with you once your kiln has shipped. Keep in mind that a 7-cubic-ft kiln packaged on a skid with a furniture kit can weigh up to 500 lbs! We suggest that you have a box cutter, drill, hammer, and at least one other person to help unbox and set up your kiln. Please keep in mind that it is NOT the responsibility of the trucking company to do anything but deliver the kiln to your address at the curb. This means that if you are having a kiln shipped to an address that does NOT have a loading dock, you need to make sure to order a lift gate service, which transports the freight from the truck to ground level. You can order this service through us here at The Ceramic Shop.
What should I do when my kiln arrives?
It is in your best interest to thoroughly inspect the kiln for damage immediately. This means completely removing all packaging and inspecting the inside of the kiln, as well.
What if my kiln arrives and it is damaged?
UPON DELIVERY: All of our kiln manufacturers, including Skutt, Paragon, L&L, etc., pack their merchandise so that it will, ideally, arrive at its destination undamaged. However, accidents happen and you should be prepared to inspect the freight for damage right away – ideally, while the carrier is still present. If the freight – your kiln – appears to be damaged, you DO have the option of refusing delivery. Check to make sure that all of your items have been delivered, and note on the carrier’s delivery receipt any shortages. If any damage appears on the OUTSIDE of the package, have the driver inspect the packages and note on the carrier’s delivery receipt the damage. Immediately after delivery, open ALL cartons to determine if there is any concealed damage. If this is the case, retain all damaged items with their packaging.
Call the freight carrier to report damage and request an inspection within 24 hours. If a call is made later than 36 hours, the carrier can deny your claim.
Confirm your call in writing by registered mail and keep a copy for your records.
UPON CARRIER INSPECTION: Retain your damaged merchandise even though the inspection has been completed. Damaged items cannot be used or disposed of without written permission from the carrier. Do not return damaged items to the shipper without written authorization from the supplier (in this case, your kiln manufacturer). If the damaged items are picked up by the carrier for salvage, secure the receipt.
DOCUMENTS REQUIRED FOR FILING A FREIGHT CLAIM:
Your carrier's loss or damage claim form
Shipper's original invoice or copy
Original bill of lading
Original paid freight bill
Carrier's inspection report
REMEMBER: It is the customer’s responsibility to file any claim. Here at The Ceramic Shop, we are willing to help you in collecting claims but this does not make us responsible for collection of claims or replacement of materials damaged or lost. We apologize, but we cannot make freight claims for customers.
I received my kiln a month ago and haven’t used it yet. When I opened it for the first time, I noticed that some of the bricks are cracked. I want a new one!
In the event that you discover possible damage well after delivery, The Ceramic Shop and your kiln manufacturer are no longer liable. Please be sure to thoroughly inspect your kiln as soon as you receive it. Carriers generally only extend a maximum time frame of 36 hours in which to file a claim following delivery of your kiln.
"How To Choose An Electric Kiln" supplied by Paragon.