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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Big Power in Small Multi-Use Kilns
We know that everyone loves their big, very capable kilns, but so many times they just are not the right solution for smaller projects. Having a smaller multi-use kiln for test tiles, making jewelry, firing metal clays, small ceramic projects, pulling vitrigraph stringer, bead annealing, or enameling is just a must in our studio. We'd be lost without our little wonder of a kiln! Here are some kilns that we really like as they do A LOT for the money... It's definitely hard to choose which one is best. It really just depends on what smaller projects you like to do and how much flexibility you need. Evenheat Copper Kiln We love this kiln because of its front-loading capability as it makes for easy access and loading. The other really nice thing is that this kiln pulls fewer watts than most other kilns, while still making the temps we need. If you have power challenges in your studio, this kiln plugs into any household 120V receptacle, so you'll have an easy time getting the "juice" you need. The Copper is also built entirely of firebrick to offer the metal clay artist the opportunity to explore materials in the higher temperature ranges. Many clays require temperatures up to 2200F and the Copper has the capability to get you there. The Copper also finds use in china and porcelain painting, ceramics, and glass making it a true multi-use kiln! Not to be left out... we also love the Evenheat V8. The V8 multi-purpose kiln is sized perfectly for home studios, teachers, instructors, and test kiln use. It's capable of all firing types and techniques including glass, vitrigraph, ceramic, metal clays and more. Its stackable design makes placement easy, especially with vitrigraph work. The V8 easily transforms into the ultimate Vitrigraph kiln with its Vitrigraph base accessory. Vitrigraph use highlights include a corner mounted thermocouple which offers more usable floor space and allows for larger pots up to 7.25". Olympic HB86E This kiln is a rocket because it heats very quickly! The reason this kiln is special is that it's super-powered, going really fast up to temp and having the ability to hold that temp for long periods. That is especially important when pulling vitrigraph stringer. This nifty little kiln is truly multipurpose! We use it to fuse, anneal beads, fire Metal Clay, and as a vitrograph. You can even fire small ceramics. The top and bottom are removable for the ultimate in versatility. This little wonder does it all! It is important to note, that when the bead collar or blank collar are added, the maximum temperature on the HB86E reduces to 2000°F. The Olympic HB89E is another great option. Same flexibility as the HB86E and fires to 2,350°F on just 120 volts but, with more space and a hinged lid. Plus, the attached stand allow this kiln to be used on any surface, including countertops. Paragon Caldera Digital This kiln is a solid workhorse that has a great reputation. It is one of vitrigraph kiln because it fires fast and stays there! Also, with a separate top and bottom, the Caldera is stackable and completely portable. The kiln is easy to carry to seminars or take on vacation. Paragon's best sellers because it literally can do anything! The Caldera fires rapidly to 2350°F so, it's used in a lot of studios as a dedicated. The basic Caldera is part of a unique kiln expansion system. You can order extra collars for bead annealing, enameling, or just depth! For a digital kiln that can do this much, the Caldera is surprisingly affordable. Jen-Ken AF3P Cube 4 w/ 4" Flip Door The AF3P Fuse Cube is perfectly powered for its size. This kiln is bigger than other small kilns. The inner dimensions are 9" square letting you stack shelves for metal clay, or put in a really big vitrigraph pot without having to purchase an extra collar! That makes this kiln a bargain. Depending on which model you order, you can do everything I listed above. You can even order additional bottoms to make this a vitrigraph. The height is a real advantage for this kiln! It is also nice and deep allowing you to fire a metal clay carbon vessel inside. In addition, you can slump and drape small items, make tons of glass jewelry and fire ceramics up to 8" tall!
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Why we LOVE Quartz Tubing!
Paragon CS-26 Whether it's offered as standard or an upgrade, we always love kilns that have quart tubing! Quart tubing provides a cleaner kiln interior and magnifies the heat to the glass. They also support and protect the elements from contamination with foreign materials that could shorten the element life. In addition, quartz tubes protect the glass from any falling debris from exposed elements. If you fire enamels, the metal oxides can cake onto the elements causing them to sag, and drop colored debris... yuk! Gail has two kilns at her studio with quartz enclosed tubes and never has to worry that anything will drop on her, or her students' glass. Check out some more kilns with quartz tubes: Jen-Ken AFG ProFusion Fiber 38 Hot Shot Oven and Kiln - HS16 PRO Clamshell Olympic Champ XL (Available as upgrade)
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Little Wisp Bowls
Bullseye Glass Quick Tip: In this Quick Tip, you will learn to create your own streaky color palette! And, it's so easy! Start by layering Clear and White Streaky sheet glass over transparent tint glass styles. Then, slump in the Cone Bowl mold to upturn the edges and achieve luscious color at the rim. You might just find yourself making bowls for days! The Cone Bowl mold is a crowd pleaser and has always been a Bullseye Glass favorite! Glass fusers have dubbed it the original “the ice cream dish mold” and who doesn't love ice cream! The steep drop of this mold into a narrow space means this is one slumping project that requires special attention to preparation, firing schedules and placement in the kiln. Check out this additional tip from Bullseye... Cone Bowl Molds for additional best practices. Also, if this is your first time using clear, white streaky sheet glass, keep in mind that it may become more translucent upon firing. Remember to remove any needle pointed edges with a diamond pad prior to slumping to ensure you get a smooth, clean edge. Finally, for handy for minor adjustments of the flat, fused blank in the mold, as well as removing the slumped dish from the mold... just use this handy Small Suction Lifter.
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Is it time to change your mechanical relays?
It seems like every November we get the same phone calls and the same e-mails... "My kiln has stopped working and I have a show this weekend. Please HELP!" With that in mind, it's important to remember... owning a kiln is like being a Boy Scout, it's important to always BE PREPARED! Murphy's law says that whenever you need your kiln most and are firing the most, that's just when it's going to have a problem. So.... we all know that an ounce of prevention is worth a pound of I told you so. This is not directed to any one of our clients who've contacted us this month with an OMG moment! This is for all of us, who are just very busy and forget to take care of the basics. And yes... this has happened to me so, you're not alone. If you don’t already know, a relay is the part of the kiln that controls the power or current to the element, allowing the element to either receive current and get hot, or to interrupt the circuit thus not allowing the element to receive current and cool down. The mechanical relays, which come standard on most kilns, are what is responsible for the ubiquitous opening and closing clicking we hear while our kilns run. ALL MECHANICAL RELAYS in U.S. kilns are virtually the same... no matter the manufacturer. Mechanical kiln relays have a life of up to “X” amount of clicks and then they fail. This failure can either be in the closed position (Yikes, my kiln temperature keeps rising and it won’t turn off… everything is ruined!”) or they can fail in the open position. (Yikes, my kiln won’t heat up at all!) If they fail, it is not the manufacturer's fault, since they do not make the relays. They test them to make sure they work at the factory, but after that... it is your responsibility. We know that all failures stink and that is why we recommend changing your relays every 12-24 months. If you are a heavy kiln user, you should be smart and change your relays once a year. Think about it like an oil change or new tires... you wouldn't let your car drive on bald tires or your engine run on old oil. Pick a month and make it kiln maintenance month. Install new relays, paint the bottom with kiln wash, etc. and give your kiln a thorough inspection. Don't be the cautionary tale!! Finally, if this is something you don't want to hassle with... you can eliminate the problem by upgrading to mercury or solid state relays and almost never have to change a relay again. In our opinion, it's the best upgrade money can buy. With mercury relays it is important to make sure that regulations in your area don't prohibit them. The following states have prohibited the import of Mercury Displacement Relays within their jurisdictions: CA, CT, RI, IL, NH, MA, MN, ME, VT, NY, LA, MD, WI. If mercury relays are not for you, many kilns come with the option to add solid state relays for an additional charge. Hot Shot takes it one step further and makes all kilns with solid state relays by default.
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Creating Hollow Beads with Cork Clay
Cork clay is the perfect filler to create hollow shapes with Metal Clay. After creating the shape with cork clay, you must allow it to dry for at least 24 hours. Do not force-dry the cork clay with a heat gun. After it's dry, coat the cork clay with metal clay. Cork clay creations are usually fired in small jewelry kilns such as the Paragon SC-3 or Cress Kilns - C1006B It is important to fire cork clay in a well-ventilated area. Open windows and circulate the air with a fan. To prevent the cork from flaming out, always keep the kiln door closed between 500° - 800°F. Also, to give the cork enough time to burn out, fire no faster than 1500F per hour. Leave the kiln’s vent plug out from the beginning until around 800 °F. Hold at that temperature for 1 hour. After the hold, insert the vent plug and continue to fire the metal clay to the clay manufacturer’s recommended temperature. ⚠️Caution: When venting materials such as cork clay, remove the vent plug at the beginning of the firing. If you forgot to vent the kiln at the beginning of the firing, do not remove the plug later. Removing it later during the firing may cause the organic materials to flame up for a moment. If you ever remove the vent plug and the cork clay flames up, keep the kiln door closed so the flames can die out safely. Do not fire cork clay in a microwave kiln (the type that is placed inside a household microwave oven). The microwave kiln fires too fast to properly burn out the cork clay. Just for fun... cereal, pasta, and bread are other good core materials. Do not use wax or Styrofoam as a core as they emit harmful fumes.
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Put a Ring on it!
Bullseye Glass Quick Tip: In this Quick Tip, explore the possibilities of a palette of rings capped with Opaline! As an overlay, Opaline scatters light for a dramatic impact on base colors. Note the blue hue it adds to the dark-valued green and the subtle changes with lighter-valued greens. But when held up to the light, it's as if the Opaline layer disappears! One secret of ring cutting is that the inner pieces must be slightly smaller in diameter for the best fit! A central circle cut to the same dimension as the inner ring will not fit, in the same way a ring and circle cut from the same sheet won't fit back together. Larger, narrower rings are easier to cut because they're more flexible than smaller, wider rings. When trying to remove the rings, make a single score perpendicular to the inner circle and run it gently, then wiggle the ends of the ring up and down to ease it off of the central circle. This will leave a seam in the ring, but this usually fuses together with little visibility, particularly under a cap of Opaline.
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