ELEMENT STRETCHING & INSTALLATION INSTRUCTIONS

1. To determine total length to stretch an element measure total length of element grooves.
2. Mark floor with two marks for stretched length.
3. Initially stretch element about 50% of length of its final fully stretched length. Examine for evenness of stretch. Selectively stretch close wound sections to provide uniformity of stretch.
4. Repeat this procedure several times.
5. You will have to pull element beyond last mark in order to obtain full stretch.
6. If overstretch occurs insert a metal rod or small diameter dowel into the element coil and compress.
7. Stretch uniformity is necessary for satisfactory element life.
8. Take off the cover panel to expose the element connections.
9. Replace one element at a time so that you do not make a mistake with the wiring.

REPLACING ELEMENTS AND ELEMENT HOLDERS

1. Remove old element, check failure points for evidence of contamination on the element and the element holder.
   
   
2. If the element holder is contaminated it will cause rapid failure of the new element. Replace contaminated holders with new ones.
   
   
3. If element is hard to get out of the holders (because of growth of the element) you can try heating up the kiln slightly so as to heat up the element slightly to just the point where element is slightly pliable - don't let it get red. This will soften the wire. Then turn off the kiln and disconnect all power to the kiln. Then, using heat protecting gloves such as welding gloves or heat treating gloves and a pair of needle nose pliers pull out the softened element. IF YOU DECIDE TO USE THIS METHOD BE VERY CAREFUL OF THE POTENTIAL FOR BURNING YOURSELF.
   
   
4. Carefully remove old element holder by striking with screw driver and hammer, not too hard, however. Under cut brick at bottom of grooves only. Insert new element holder while simultaneously adding refractory cement under holder. Just one or two spots are required. On sectional kilns like our old "K" models or "J" models the holder may be easily replaced by carefully pulling the elements out of the element holders of the brick section involved and allowing them to hang loose. Take great care not to "break" the element as they are very brittle after firing. Loosen the sheath by unscrewing the hose clamps just enough to allow the brick to be pulled up just enough to allow removal of the defective element holder and replace with new one. When ordering a new holder provide model number of kiln and length of the element holder. After installation of the new element holder tighten the hose clamps lightly allowing readjustment and line up of brick. Tighten case. Replace element. CAUTION: Make certain this operation is performed on a flat surface to insure proper section to section seal.

FACTORS SHORTENING ELEMENT LIFE

1. Contamination (such as glaze or kiln wash.) Silica, a main ingredient of both of these, attacks the element wire.
   
   
2. Tightly wound areas on element coils resulting from improper stretch. Have the elements been stretched evenly? This is critical. If the element coils are bunched up along the length of the element the element will overheat where the coils are too close. Replacement elements are shipped unstretched and stretching instructions are included with the elements. Also see section above on stretching elements.
   
   
3. Glaze accidentally rubbing off into holder and on element in loading kiln. If such rub off occurs immediately vacuum thoroughly. Glaze will cause very rapid failure.
   
   
4. Blow ups or explosion of bisque ware cause small pieces of clay to be blown into holder and element. If not immediately removed clay may melt contaminating element and element holder. To avoid this make certain clay is very dry before firing and, in the case of heavy handmade pieces, fire on low for a long period until you are sure ware is dried out thoroughly. If you hear a "pop" when firing such pieces, stop firing, cool the kiln. If blow-up has occurred, vacuum all element grooves very thoroughly.
   
   
5. Firing pieces too close to elements. We recommend at least 1-1/2" from piece to element. Further if large flat surfaces are parallel to kiln wall.
   
   
6. Reducing atmospheres will destroy elements. Do not use wood chips, oils and other materials to generate a reducing atmosphere. A very rapid element failure may result.
   
   
7. Excessive soaking time will accelerate increase in element resistance. The higher the temperature, the longer the soak, the sooner the element will decrease in life. Usually short soaks work fine.
   
   
8. Are they genuine L&L elements? There are a number of people selling "replacement elements" for kilns. These people do not have access to the proper design information for L&L elements. Designing an element is a complicated process which balances such things as voltage, wire diameter, watt density, stretch ratio, etc. It is very easy to make an element that has the same watts as an L&L element and have nowhere near the other design qualities that result in long element life.
   
   
9. If the failure is taking place at the element end it may be twisted too tightly, causing stress at terminal through holes. This causes local overheating at the "through hole", and element failure. (Contact factory.)
   
   
10. Make sure all elements are heating. If not all elements are doing their share of the work then the other elements will not last as long.
    
    
11. Are any waxes, oils, carbon, fluorine, fumes present? Are you using any lead glazes? Iron-Chrome-Aluminum elements require an oxidizing atmosphere to give dependable service. The aluminum in the element forms a protective aluminum oxide. Oil from tools or carbon from wax burnout will attack the element coating. Halogens such as chlorine or fluorine will attack the elements. Molten metals, for instance, zinc, aluminum and copper, react with iron- chrome-aluminum elements. Moreover, these metals oxidize easily and their oxides have an unfavorable effect on iron-chrome-aluminum. The salts of the alkali metals, halogen salts, nitrates, silicates, and compounds of borax, disturb the formation of oxide and are, therefore, harmful to these elements. This is also true of the oxides of such metals as copper, lead and iron. Do not use with free carbon. Lead oxide attacks the protective alumina oxide coating on the element. If you are using lead glaze (or are creating any of these other problems) be sure to use a kiln vent. Also try firing every other load or as often as you can with a non corrosive load (such as a bisque firing.) This will help the element restore its protective alumina oxide coating.

ELEMENT TERMINAL BURN OUT

1. Sometimes the ends of the elements can burn out at the element terminals (connections). This can be due to any or all of the following causes:
   
   
2. The element ends are not twisted properly. If the twist is too loose this could general extra heat at the element ends.
   
   
3. The holes where the elements go through the firebrick walls are too large. This could cause too much heat to escape from the kiln thereby overheating the element terminals. This can be remedied by lightly stuffing ceramic fiber (Fiberfrax) in the element holes.
   
   
4. The element connection hardware may not be tight enough. A loose connection can generate heat and cause oxidation of the hardware which in turn will cause a worse electrical connection (because of resistance) and more heat. Replace with new hardware. There should be a lock washer (so the screw terminal does not turn), and a washer on either side of the element as it is turned around the screw. The hardware should be nickel plated.

Why do elements in electric kilns fail? What can you do to extend element life and save on kiln maintenance costs?

1. Most electric kilns in use today use coiled wire made of a very special high temperature alloy of iron-aluminum-chrome. The chief advantage of this alloy over others that were used in the past is that it resists very high temperatures (up to about 2400°F). It does this partly by forming a very tough alumina oxide coating on the outside of the wire. The disadvantages (or weaknesses) of the alloy is that it becomes very brittle after firing, the wire grows with use, the resistance increases with age, and anything that harms the oxide coating can ruin the element.
   
   
2. Keeping these factors in mind, the kiln user must be careful not to allow any contamination on the elements. Reducing atmospheres, carbon compounds (such as might be found in some clays), glazes, oxides of lead, halogens, fluorides, silica compounds (such as found in kiln wash) will all attack the alumina oxide coating. Reducing atmospheres will be caused by burning carbonaceous materials in the kiln - something never recommended by kiln manufacture's. Reduction firing should only be done in gas kilns.
   
   
3. Even stretching of the coil is also critical. Once the elements are fired they can not be easily restretched. If the coils become bunched up in certain places because of improper initial stretch, or because of rough firebrick making the elements stick while they expand and contract, the element will overheat and burn out where the coils touch each other.
   
   
4. The condition of the firebrick or element holders supporting the element is important. The brick or element holders must be clean and free of kiln wash, glaze and crumbling firebrick. Grooves or holders must be in good condition. Because it can be difficult to repair firebrick grooves many owners overlook this. However, if an element droops down out of a broken groove you may have lost that element. Although pinning the element in place with alloy pins can help, this is not an ideal solution because the pins tend to come lose over time (because their expansion factor is different than firebrick.) Ceramic holders have the advantage of being stronger and less prone to damage than firebrick in the first place, and easier to replace if they do get damaged or contaminated.
   
   
5. Keeping the element as cool as possible is one thing the kiln owner can and should think about. The life of elements goes down logarithmically with element temperature. For instance an element operated at 2100°F may last twice as long as an element operated at 2200F but four times as long as an element operated at 2300°F. There is a big difference between element coil temperature and kiln temperature. The coil may be 50F to 150F hotter than the kiln. This differential will be influenced by the density of the load. Dense loads will absorb more heat and the elements will work harder (and hotter) to get the heat into the kiln. You should never load your ware closer than about 1-1/2" from the elements. It is especially important to keep the load shelves away from the elements. You want to get the heat away from the elements and allow it to circulate within the kiln. Work or shelves that are too close to the elements not only prevent air circulation but they reradiate heat back to the elements causing them to overheat. If the element is buried behind insulating firebrick it will get hotter than it needs to and the life will go down dramatically. Dense ceramic holders can help this condition because they transmit the heat from the element more efficiently.
   
   
6. Element design is often the paramount factor in element life. The three main aspects to this are watt density which is the ratio of watts to surface area of element (this should be as low as possible), element stretch ratio and the ratio of wire gauge to coil diameter. There is unfortunately not much the kiln consumer can do about element design except to trust the manufacturer of the kiln. However, keep in mind that the relationships between the competing "ideals" in a design make element design difficult and time consuming. The kiln consumer should be aware that cheap replacement elements from outside vendors may not have the proper design and may fail sooner. Also, there are several cheaper grades of iron-aluminum-chrome alloy available and there is no way for the average consumer to know that he or she has received the top grade (which is necessary for the ultra high temperatures encountered in most ceramic hobby kilns.) Only buy elements from a reputable source.

If you ever have to reform an element (for instance, if an element gets out of its brick slot or element holder and droops down) you can not do this cold. The element must first be heated (not quite to red heat) and then carefully reformed with a tool such as needlenose pliers. The heating of the alloy will soften it.

Long soak times will accelerate the element aging process so try not to soak at final set point for any longer than you absolutely need to.

No matter what you do elements will increase in resistance over time. This is because the part of the wire that actually carries the current gets thinner as more of the aluminum is transformed into alumina oxide. Element resistance is measured in ohms. As resistance increases the current draw (amperage) will go down and the firing time will increase. The only reliable way to know which elements need replacing when the kiln starts slowing down is to measure the ohms of each individual element with a digital ohmmeter. You must isolate each element for this measurement. Then compare each value with the ohm values provided by the manufacturer. Typically when the element has increased in resistance by 9% it is time to change it. Keep in mind that for kilns with graded elements (where elements vary in power output from top to bottom to avoid zone switches) you may need to replace all elements as a set. In kilns with individual zone control switches you can adjust for variations in element output caused by resistance change.

Keeping your elements and element holders or grooves clean, using only good elements to start with, properly stretching and installing them, and making sure that they transfer their heat as efficiently as possible, you can do a lot to maximize element life and minimize your maintenance costs.