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Showing FAQs 61of 61    


Are slower heating rates better for the kiln than fast heating rates?

Fast heating rates are no harder on kilns than slow rates. You can fire as fast as you want.

... [More]

Do kilns fire cooler on the bottom?

Kilns tend to fire cooler on the bottom, but not because heat rises. Movement of heat through convection ends at around 1100 degrees F. At 1700 F, a cubic foot of air has only about one-tenth the number of molecules as at room temperature. This is wh ... [More]

Does drying leather-hard greenware in the kiln on a long pre-heat adversely affect the kiln’s bricks and elements?

This is an expensive way to dry greenware. However, it is okay to dry greenware in the kiln as long as the temperature gets no higher than 200 F (93 C) and the kiln is well vented. Do not raise the temperature until the clay has dried out.

T ... [More]

Does it cost less in electricity to find the kiln at night?

In some areas, electricity is cheaper at night. You can find out by asking your utility company if they have a "time of use" plan. Also, ask if they have a separate demand charge. This is where they charge an extra fee when your use more electricity ... [More]

Does wax resist used in pottery firings void the kiln warranty?

No. Wax resist in pottery firings won’t hurt the elements or the firebricks. It does not void the warranty.

... [More]

During firing I can see the red glow through the spaces between the kiln sections and the lid, plus sometimes from the peepholes. The peephole plugs do not have a snug fit. Does this waste energy?

There is little heat loss through a loose-fitting peephole plug or the cracks between kiln sections. This is because at 1100F / 593C and higher, the air molecules are spaced so far apart inside the kiln that heat no longer moves by convection. This i ... [More]

During the first firing of a new kiln, do you fire the kiln empty?

Fire only empty shelves, posts, and witness cones the first time you fire the kiln. Some people have fired the kiln the first time with all the shelves stacked together in the bottom. This can crack shelves. Instead, separate the shelves with posts, ... [More]

How do I adjust the switches on my SnF-82-3 so I can operate the kiln with a portable TnF2 controller?

Plug the TnF2 into the wall outlet. Install the thermocouple using the instructions that came with the TnF2, and plug the kiln into the TnF2.

Turn the top switch to MAX. Turn the second switch counter-clockwise about a quarter turn. Then tur ... [More]

How do you figure the cost of firing a kiln?

The cost of electricity is figured in kilowatt-hours (KWh). A kilowatt-hour is 1,000 watts of electricity running for 1 hour. (10 – 100-watt light bulbs glowing for one hour consume 1 KWh of electricity.)

To find what the power company charge ... [More]

How do you slow down the firing?

The answer depends on the type of kiln.

Infinite control switch: To slow down the firing rate, turn the switches to a lower setting for a longer period. For instance, instead of firing on Low for the first hour, fire on Low for the first 1 1 ... [More]

How do you turn off a Paragon SnF kiln?

To turn off the Paragon SnF manually after the witness cone bends:

The top switch is an infinite control. Turn to the OFF position.

The second switch (and third, if you have one) is a switch-timer. Turn clockwise until it clicks. ... [More]

How do you use kiln wash?

This information also applies to glass separator.

Kiln wash does not melt at high temperatures and thus forms a protective barrier between kiln shelves and ceramic glaze.

Do not apply kiln wash to the bottom of a ceramic fiber kiln ... [More]

How does a beginner get over the fear of a new kiln?

Recently a friend told me that she had been afraid of her Paragon glass kiln until she began firing glass bottles. The bottles were free, so she could experiment all she wanted without worry about ruining expensive stained glass. Firing bottles took ... [More]

How does one avoid damaging the top bricks when leaning down into a kiln to load it?

Trace the top rim of your kiln onto newspaper or cardboard. Use this template to make a plywood loading support. The plywood should be about 2 feet long and fit over the top rim of your kiln's firing chamber. Lean over the plywood during loading ... [More]

How does overfiring the kiln damage the kiln?

Firing beyond the temperature that the insulation is designed for can damage the insulation. Insulating firebricks can actually melt when fired too high. Overfiring clay can make the clay puddle on the shelf and kiln bottom, ruining these surfaces. ... [More]

How does the lid prop work?

Ceramic pieces release gases and water vapor during firing. Venting allows these gases to escape. Paragon’s fall away Prop-R-Vent is installed on the switch box of most top-loading kilns. The prop supports the lid in an open position during the venti ... [More]

How much does slow cooling of ceramic ware reduce the element life of a kiln?

Controlled cooling reduces element life--but the amount of wear varies depending on the kiln wall thickness and length of the controlled cooling. (A thick-walled kiln can often achieve the effects of slow cooling without even turning on the elements ... [More]

I am concerned about the light that appears under my kiln lid during firing.

The light that you see under the lid is normal, as long as the lid is not rising in front.

The inner lid surface expands more than the outer cooler surface. Therefore, it bows inward slightly toward the firing chamber. This is normal. For thi ... [More]

I don't understand why my kiln fires at a progressively slower rate as the temperature climbs.

Kilns slow down as they go up in temperature. Their fastest firing rates are in the lower temperature range.

The maximum firing rate of a kiln depends on the type of insulation, element design, amount of wear on the elements, the size of the ... [More]

I fired my SC-2 kiln for the first time and turned it off because of a strong smell. I also found dark discoloration inside the kiln.

During the first firing, you may smell a strong odor from your kiln. This is normal and is caused by the burning of binders in the ceramic fiber firing chamber. The odor is accompanied by a discoloration, which disappears after the kiln reaches about ... [More]

I have been using K23 bricks for raku. I need them to cool down quick, because I travel and take the kiln apart. If I used K26, would they cool as fast?

K26 firebricks cool faster than K23, because the K23 firebricks are more porous and absorb more heat than the K26. But the difference in cooling rate is very slight.

... [More]

I heat treat knives and pull them out at around 1900F to cool the knives. I’ve heard that the kiln should be allowed to cool to room temperature before opening. So, am I doing this wrong?

The kiln should be allowed to cool to room temperature before removing glass, pottery, or low-fire ceramics. Some materials such as copper enameling and high carbon tool steels, however, are normally removed at high temperatures. The sudden change in ... [More]

I know a potter who fires horsehair pottery to 1735 F, shuts off kiln, lets it cool to about 1100 F and removes pieces. Is this hard on the elements?

Removing the ceramic pieces at 1100 degrees F should not harm the elements or firebricks. Heat treating kilns are routinely opened at high temperatures to remove steel parts. This does not seem to affect element life. Our main concern would be operat ... [More]

I usually use the 3 or 4 setting on the infinite control switch. Is there a chart that tells you what temperature range each setting represents?

The infinite control switch has no temperature chart for the switch positions. This is because the infinite control is not a precise temperature controller. Rather, it cycles the elements on and off to change the rate of heating.

... [More]

I want to fire decals. Is there any way to vent the lid on a kiln that is equipped with a lid safety switch?

Raising the lid to the vented position should not activate the lid safety switch. You should be able to raise the lid an inch or so before the safety switch shuts off the elements.

If the safety switch shuts off the elements with the lid in t ... [More]

I’ve heard that crash cooling is not good for kiln bricks and elements. How about rapid ramps up?

Fast ramps are no harder on kilns than slow ramps. So you can fire as fast as you want. Forced cooling doesn’t seem to be hard on kilns. However, forced cooling could break a shelf.

... [More]

If the kiln is firing longer than usual, how can you tell if it is overfiring?

It is useful to observe the color of light under the lid or door and around the peephole plugs during each stage of firing. If you have a digital kiln, notice the temperature for dark red, cherry red, yellow, bright yellow, etc. Mentally note the col ... [More]

Is fast firing or cooling hard on the kiln bricks and elements?

Fast firing is no harder on kilns than slow firing. So, you can fire as fast as you want provided the materials you are firing can withstand it. Forced cooling doesn’t seem to be hard on kilns, either. However, forced cooling could break a shelf or t ... [More]

Is it necessary to be home the whole time the kiln is running? Can I run it when I'm asleep?

We recommend that you fire the kiln while you are home, especially toward the end of the firing. You can program a delay fire on digital kilns so that the kiln starts at a time that will suit your schedule.

You can fire the kiln at night, but ... [More]

Is it necessary to ever recoat the kiln bottom with kiln wash? If so, how often? The kiln wash on the shelf deteriorates pretty quickly.

The kiln wash adheres to the firebricks better than it does to shelves, because the firebricks are porous. Therefore, it is rarely necessary to apply more kiln wash after the first application when the kiln is new. Apply more kiln wash to bare areas ... [More]

Is it normal for the kiln to make a pinging sound?

A faint pinging sound is normal. It is the insulating firebricks expanding and contracting during firing. If the pinging sound is coming from glass or pottery, however, you will probably find cracks in the glass or glaze.

... [More]

Is it okay to fire a kiln in the winter when the firing room is below zero F?


Yes. Turn the kiln on low for the first few hours so the kiln heats up gradually.


It is okay to store digital controllers in sub-zero weather. But before operating, raise the room temperature to 32°F ... [More]

Is it okay to fire a kiln when the room gets hot?

Switches, relays, and controllers on an electric kiln fail when the room temperature gets too high. For example, a customer kept sending us burned-out infinite control switches. They eventually sent us one of the switch knobs, which had gotten so hot ... [More]

Is it okay to kiln wash the underside of a kiln shelf?

We recommend kiln washing only the top of the shelf for ceramic firings. Kiln wash applied to the underside of the shelf can flake off and land on glazed ware underneath. However, for a glass kiln with only one shelf, it would be okay to kiln wash bo ... [More]

Is it okay to squirt alcohol into a kiln for reduction firing?

We recommend that you not squirt alcohol into a hot kiln. Alcohol in a kiln can be more dangerous than a molotov cocktail. Not only is alcohol highly volatile, but it is almost invisible when it burns, making it especially dangerous.

... [More]

Is it safe to fire six 120-volt kilns during a seminar?

It is safe to have six kilns firing at the same time as long as they are each plugged into separate 120-volt circuits that have been properly installed by an electrician. If the center when you are teaching the seminar doesn't have six separate circu ... [More]

Is the temperature inside the kiln’s switch box higher than the ambient room temperature?

Yes. The temperature inside the kiln's control panel is higher than the ambient room temperature.

As a general rule, the room temperature, measured 3 feet from the electric kiln, should not exceed 110 degrees F. Use fans to lower the tempera ... [More]

Is there a way to make a kiln fire more evenly throughout the firing chamber?

1) Load more ware in hot sections of the firing chamber and less ware in cool sections. The greater the density of ware, the more heat required in that section of the firing chamber. By changing the load balance inside the kiln, you can alter the hea ... [More]

Is there any documentation that has the approximate rate of speed on the infinite control switch? For example, the heating rate when the knob is set to 2.5.

The heating rate at a particular infinite control setting varies from one kiln to another. This is because the rate at each setting depends on the size of the kiln, amperage, type of insulation, etc. Another factor is the age of the switch.

... [More]

My front-loading kiln has a gap between the door and the firing chamber. Is that normal?

There should be no gap between the door and the firing chamber at the side toward the door latch. There should be a gap, however, at the hinge side of the door. When the kiln is cold, you should see a gap of about 1/16" between the hinge side of the ... [More]

My kiln lid is cracked and drops dust onto glazed ware. How can I get around the problem until I replace the lid?

Position large ware on the lower shelves and smaller ware on the top shelf. Arrange the smaller pieces so they are not directly under the crack where the dust is falling.

You could also fill the firebrick crack with ceramic fiber. Roll the fi ... [More]

My kiln shelves are flaking off on the edges creating kiln trash. I brush the edges off before I load, but is there anything I can do to repair them?

The flaking is probably loose kiln wash. As you apply kiln wash to the shelves, wipe the edges before the kiln wash dries. Kiln wash tends to accumulate around the edges of shelves and flake off later.

... [More]

My kiln usually takes 10 hours to fire. I’m wondering why the last firing took 15 hours. I loaded more shelves this time. I fired tiles on shelves that were spaced an inch apart.

Loading a kiln more densely can increase the firing time. The extra mass inside the kiln requires more energy to fire the load. If the slower firing causes a digital controller to flash an error message, then program a slower firing rate.

... [More]

Pinging or popping noises are coming from my kiln as it cools. Is that normal?

Faint popping noises are the sound of the firebricks and the metal jacket cooling down and shrinking. This is normal. It is similar to the sound of a muffler on a car as it cools.

Popping noises from inside the kiln may indicate that ceramic ... [More]

Recently, I read that one should never leave a kiln unattended. I had previously been firing glass while away from home or overnight. Should I avoid this?

We recommend that you monitor the kiln during operation. This does not mean giving it your constant attention. Just check on it occasionally, especially toward the end of the firing. This advice applies even to digital kilns that shut off automatical ... [More]

Should I monitor the kiln while it fires or allow it to turn off automatically?

Paragon recommends that you monitor your kiln during firing. In most situations this doesn’t mean constantly watching the kiln. You are undoubtedly too busy for that. But you should check the kiln occasionally. Monitor the kiln more frequently as it ... [More]

Should you insert the peephole plugs during firing?

It is important to vent the kiln thoroughly at the beginning of the firing. Leaving the peephole plugs out at the beginning helps venting.

Most people leave the top peephole plug out throughout the firing. But if you are getting a glaze defec ... [More]

The first time I fired my new SC-2 kiln, I could smell something burning, so I lifted the bead door to peep inside and noticed that the ceramic fiber shelf had turned brown.

The ceramic fiber shelf contains binders that burn out during the first firing. Do not be concerned if the shelf becomes discolored. It will turn white again after the kiln reaches about 1000°F / 537°C.

... [More]

The peephole plug on my kiln falls out of the peephole during firing. How can I solve this problem?

You can wrap the peephole plug with a little ceramic fiber. That will hold the plug in place. Or you could also plug the peephole with ceramic fiber.

If you have a downdraft kiln vent, it is important to keep the peepholes plugged during fir ... [More]

To what extent do the fumes from clay corrode the kiln?

The two elements in clay that are especially corrosive are fluorine and sulfur. Avoid clays with large amounts of these elements. Your clay supplier should be able to tell you how much of each is in your clay. Clays that are especially troublesome ar ... [More]

What do I need to know about the wall outlet for a studio kiln?

The wall outlet should be installed so that the kiln cord hangs downward-not upward-from the wall outlet. Do not place the outlet so close to the floor that the kiln cord bends at a sharp angle. In either case, the plug may not seat properly in the o ... [More]

What is a practical way to monitor a kiln during operation?

The digital controller and Kiln Sitter used on kilns are very reliable. But if they fail, they can overfire the kiln and destroy all the ware, the shelves and posts, and even the firebricks. This is why all kiln manufacturers recommend that you monit ... [More]

What is the cone-shaped ceramic object that came with my new kiln?

The ceramic cone is the peephole plug. It fits into the tapered hole on the side of the kiln.

... [More]

What should be included in a firing logbook?

One of the easiest ways to learn about your kiln is to keep a firing logbook. If you are firing the kiln for the first time in several months, you can review your logbook to regain a quick “feel” for the kiln. The logbook is vital if you are experime ... [More]

What would cause a kiln to overfire?

A kiln could fire at full rate if a relay locked on, a thermocouple failed, the Kiln Sitter failed, or the contacts in a switch stuck in a single-switch kiln.

Estimate how long your kiln would take to bend the witness cone if for some reason ... [More]

When is it okay to unload the kiln?

As a general rule, let the kiln cool to room temperature before unloading. You should be able to remove the ware with bare hands. If you unload ware while the kiln is still hot, you risk damaging the shelves, crazing glazed ware, burning a hand, or e ... [More]

When should the peephole plugs be left out during a firing?

You can leave the peephole plugs out for some firings. This improves oxygenation inside the kiln. However, this may cause cold spots in the kiln, especially if there are air drafts in your firing room. If you leave the peephole plugs out, keep ware a ... [More]

Why did smoke come out of my ceramic fiber kiln the first time I fired it?

The smoke that came off the kiln during the first firing is normal. It is the binders burning out of the fiber insulation.

... [More]

Why do you recommend firing a new kiln with only kiln furniture in it during the first firing?

The kiln should be fired without greenware during the first firing so the elements can form a protective coating before being exposed to clay fumes. The main reason, though, is to give the new kiln owner practice in firing without worrying about ware ... [More]

Will opening a hot kiln to remove raku pieces damage the firebricks?

Electric kilns are generally made with K-23 firebricks, which have a low alumina content. (K-25 bricks have a higher alumina content.) Low-alumina firebricks can withstand dramatic temperature change without cracking.

It's better, of course, ... [More]

You know what? I'm still a little scared of the kiln. Is that normal?

Yes, it is normal to be afraid of the kiln until you have gained experience. But it won't be long before you feel confident enough as a kiln user to offer advice to beginners. Firing a kiln is like riding a bicycle or driving a car--the beginning sta ... [More]

Showing FAQs 61of 61    

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