FrogBlog
How Low Voltage Affects Firing Time
Knowledge is POWER! Making sure you have the correct voltage is one of the most important factors of kiln efficiency! Plug the kiln into the correct circuit. Low voltage can double the firing time. If your kiln is firing too slowly, make sure the voltage listed on the kiln’s electrical data plate matches the voltage of the electric circuit. The electrical data plate is usually located on the side of the kiln or the switch box. Firing a 240-volt kiln on 208 volts reduces the kiln’s power by 25%. Even a small drop in voltage can affect the firing speed. Low voltage has the same effect as firing with worn out elements. Even a small drop in voltage can slow down your kiln. For example, we test-fired a 120-volt kiln that took 5 hours and 3 minutes to reach 2331°F (1277°C). On a separate electric circuit, the same test kiln took only 2 hours and 30 minutes to reach 2350°F (1287°C). The difference in voltage between the two circuits? Only 7 volts. Fire the kiln when the voltage is highest. Turn off other large appliances. If your kiln ever slows down temporarily, do not assume that it is due to worn elements. The voltage to your building may have dropped due to peak demand. Have an electrician check the voltage under load while the kiln is firing. Until you know the voltage, an amp reading of the kiln won’t tell you much, because low voltage also causes low amperage. If the voltage is low during a period of peak demand, fire your kiln when the electrical demand is lower and the voltage is higher. Fire at night or early morning. Also, turn off other large electrical appliances such as a clothes dryer while the kiln is firing. Program at a slower rate. A digital controller will show error messages when it has been programmed at a faster rate than the kiln is capable of firing. This can happen even when the voltage is normal and the kiln is new. You may be using a firing schedule that is designed for a faster kiln. In this case, program at a slower rate. Moist clay can slow down the kiln. Another reason your kiln may be firing slowly is that the firing chamber has too much moisture. Firing moist ceramic greenware or moist glass molds can slow down the kiln. Dry these materials before firing them. Reduce the load density. Overloading a kiln with a dense load of ceramics and kiln furniture can also slow down the firing. Have the power company check the transformer. If the kiln still fires too slowly after following the suggestions above, have the power company check your voltage and readjust the transformer for your area if necessary. You can also request that your power company put a voltage recording unit at your location to check the voltage over an extended period.
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The Fear of Buying your First Kiln
Don't sweat it! We've got you covered.From glass to pottery, heat treating to annealing... we have handled thousands of questions that revolve around buying your first kiln. So, we thought we would share our favorite nuggets of advice from some of our most frequent questions.Q1: I am considering buying my first kiln. The choices and information seem overwhelming as they all look so similar. How do I know which one is right for me?It can be an instant information overload. We think that choosing a kiln becomes simpler when you narrow the search with these factors: The size of the electric circuit in your studio... your kiln choice will be limited by the number of amps available. The size of the kiln... estimate how much firing chamber space you need. For glass and clay, you may also want to consider the shelf size, too! Front loading or top loading, a choice with real consequences for ergonomics, capacity, and price. Max firing temperature. After you reduced the kiln selection search with those four factors and make a list of models that you are considering. Then, compare those kilns and manufacturers in greater detail. This process will make everything better, promise!Q2: I’m nervous about ordering my first kiln... and, have so many questions. Do you have any pointers that will help? We totally understand that ordering a kiln can be complicated. But, it doesn’t have to be. Here is a great checklist to help you avoid any issues: Is your dealer knowledgeable about firing? This can be as important as the price of the kiln. What about warranty repair? Make sure you understand how the manufacturer handles the warranty. If comparison shopping, have you asked about the cost of crating or residential delivery? Are you paying extra for the stand as some are not included? Do you need to order a kiln shelf? Most kilns do not include them. Do you have a covered, well-ventilated location for the kiln, protected from the weather? Is the area free of flammable materials? If you are going to use the garage, plan on parking the car in the driveway during firing. Is the kiln room large enough? You will need 12" of additional clearance on all sides of the kiln during operation. We do not recommend small, enclosed rooms such as closets. Will the kiln fit through the doorway? Measure to be sure. Sounds crazy but, we know of cases where doorways had to be torn down to move the kiln into the firing room. Are you sure about voltage and electrical phase? 240 and 208-volt outlets cause confusion because they look the same. Check with your electrician, if in doubt. Ordering a kiln of the wrong voltage can be very difficult to remedy! Will you need special wiring? Figure this into your budget before ordering the kiln. Q3: How will putting a kiln in my garage affect my homeowner’s insurance? Our friends at Paragon shared this info regarding homeowner’s insurance: Some insurance companies simply don't insure kilns. No matter what you tell them, they won't change their minds. Other insurance companies need extra information--i.e., the kiln is UL Listed--before they will OK the kiln. If they need more information about safety, we will be glad to supply it from the manufacturer. Still, other insurance companies have no problem with kilns and don't even care if you have one. A properly installed and operated electric kiln is very safe. Do not leave it unattended during operation, and disconnect the power when not in use. Keep flammable materials out of the firing room. If you fire the kiln in a garage, remove cans of paint and gasoline. Store them in a separate building such as a garden shed. If you follow these basic rules and the others listed in the manual, your kiln will be a source of joy rather than of worry.As always, if you need help or have questions... call us! We are happy to help!
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Discoloration on kilns with fiber
Fiber kilns are constructed of rigidized fiber to keep the walls nice and stiff. Some kiln companies pre-fire their fiber at the factory to a satisfactory temperature so that any excess rigidizer burns away while others do not. As you can never be 100% positive that all of the excess rigidizer is gone, a good fiber burnout is usually necessary. With that said, before you put anything in the kiln, fire your new fiber kilns up to 1500°F and hold for one hour. Make sure to do this in a well-ventilated area, like an open garage, near an open window or your back porch because as the heat increases, the excess rigidizer may begin to steam, and well, yes even get a bit stinky. We get a lot of calls about this but, don't panic as it is totally normal. As the process continues, the nice white fiber board may even begin to turn brown and discolor. But, once the temp reaches 1500°F the toasty looking area should return to pristine white. If there is a lot of rigidzer, the area may remain slightly discolored or seem stained. Again, don't worry, as this will not effect the firing of the kiln, or later, the glass inside. Discoloration happens a lot when you use fiber papers like Thinfire or Papyrus. It’s just happening inside the kiln, so you don’t see it. If you vent your kiln while using these papers, the burnout process can discolor the edges of your kiln lid. Again, this just isn’t a real problem, just a cosmetic blemish. Think of this as smile lines from the joys of using your kiln! Learn more about fiber vs. brick kilns...
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