Questions about Kilns

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The first thing to get your head around that it’s not like your kitchen oven and it’s not a piece of furniture. Kilns reach extremely high temperatures, probably more than five times the maximum temperature of your oven. Although safe when used as intended, they are not a toy and if you don’t want to read the manual and learn how to use one safely then you may be better off utilising a firing service.

There is a saying; ‘If you’ve fired one kiln, then you’ve fired one kiln’. Each kiln is different, and most firings are different, therefore learning how it fires and getting the results you want is just as much part of the ‘artistry’ of pottery as the creating the ware and glazing. It takes time, practice and experience.

A kiln is a relatively simple machine and only a few things can go wrong with them structurally. If you are having problems then the cause is likely non-kiln related (moisture, electricity, programming, ventilation, loading & ware related). Honest and accurate feedback helps us support you to resolve any issues.

All clays and glazes release toxic and corrosive gases during firing. Ventilation is essential and if you think you’ve done enough, you should still probably double your efforts! These toxic gases will corrode metal, which will occur quickly if ventilation & air movement around your kiln isn’t adequate and/or you are using certain clays and glazes.

Due to the extreme temperatures, kilns expand and contract significantly with each firing. They are built to do this, and bricks will get cracks to release the pressure and things may work loose over time. This is all normal and looking after your kiln along with some simple maintenance, will help you get the best possible lifespan from your kiln.

Our kilns are a studio’s workhorse, and we build our kilns accordingly to ensure maximum functionality and affordability. If you are wanting a fashion accessory, then our kilns may not be for right for you. 

Selecting and purchasing a kiln can sometimes be a daunting task. To help alleviate this, here is our step-by-step guide to assist you in selecting a kiln to suit your needs.

Electric or Gas?

Electric kilns are much easier to operate and control compared to gas kilns. They are easier to install and can usually be placed in a location that would be unsuitable for gas kilns, given the emissions from gas burning kilns. Consequentially, more potters, glass studios, jewellers, dental technicians and small industrial companies use electric kilns.

Gas kilns are more flexible in terms of controlling the kiln atmosphere; you can decide on oxidation versus reduction firing (we never advise reduction firing in an electric kiln). They are also ideal for raku. Another benefit of gas kilns is that they are better suited to high temperature applications e.g. porcelain (temperatures in excess of 1300c).

How much power do I have available?

A key factor that is sometimes overlooked when deciding on a kiln is the power available to operate the kiln you are considering. Typically, most Australian homes are supplied with single phase 240V 60A electricity. The standard household power point is rated to 10A only. As a result only our smallest kilns can be plugged directly into a standard power point. All other kilns will require either an upgraded electrical power point, or alternatively be wired directly to your household power. This work must be undertaken by a registered electrician, and we always advise you seek the advice of an electrician so you can budget on the cost of providing appropriate power to your kiln. In general, kilns larger than 6 cubic foot / 175L will require the provision of three phase power.

Front-loading or top-loading?

Front-loading kilns are generally of sturdier construction that top-loaders, and they tend to be more durable and resistant to everyday knocks. These kilns are generally easier to load as there is no need to bend over to pack them. Most are placed on a stand to bring them to a suitable height (or alternatively placed on a sturdy bench). Their main disadvantage is that they are more expensive to build and lack the portability of top-loaders

Top loading kilns usually has a cylindrical firing chamber. They are often suited to smaller work areas as no space is lost when the lid is opened. All of our top-loading kilns are fitted with wheels to allow for easy movement – this can be useful if they need to be moved to a storage area when not in use. They are also cheaper to manufacture and easier to transport. They are loaded through the lid and therefore each shelf must be filled before the next shelf is positioned, you need to bend over to load and unload them, and they depend upon the internal insulating bricks for their rigidity. 

What is the right size for me?

When deciding on this don’t forget to make allowances for any planned increase in output as well as possible changes in the type of ceramics you are making.

To determine which size best suits you, consider the following:

• What type of products/art would you like to produce? Vases? Bowls? Plates?
• If you have large pieces, do you do this on the odd occasion, and could you fire them off site?
• Consider the quantities you wish to load in each firing.
• You will usually want to fire a fully loaded kiln to get maximum efficiency. Think about how long it would take you to fill your kiln.

What kiln furniture will I need? 

The size of your products and how you intend to pack your kiln will determine how many shelves and props you will need for your kiln. Don’t forget to allow for these in your budgeting. We supply furniture kits suited to each of our kilns. We can adjust the kits to your specific requirements and individual items can be purchased separately.

Time to choose the kiln for you!

Now it's all up to you (and your finances of course!). We suggest you ready the FAQ below about 'How does the freight / delivery system work?' Remember, we are always happy to help and provide advice. 

Yes & No. To avoid boring you with pages of details (single phase, three phase, current, volts etc), kilns require significant current to heat up, the larger the kiln, the more current it will require. 

Any kiln larger than our Craft 25, Mercury 30 or Plug&Fire will require the use of an upgraded power point. (Check out our resources section for a chart that shows what is required). Sometimes this is a very simple task, sometimes it can be a costly nightmare! We always advise that you seek the advice of a registered electrician to ensure that you have access to adequate power to allow your kiln to perform as it should. The kiln you buy may be limited by your available power capacity, as if there is inadequate power, you kiln will be unable to reach higher temperatures, or take a very long time to do so!

Yes, it important to monitor a kiln during the firing process. 

Safety should always be your paramount concern when working with kilns.

Kilns are not a ‘set & forget’ piece of equipment, they operate at extremely high temperatures and must be treated with the respect and awe that they deserve. Despite multiple safety features, your kilns component’s function in an erosive environment with extreme temperature fluctuations and corrosive gases.

Just because your kiln has a controller that can regulate the firing process, periodic checks and supervision is still essential (we recommend at least hourly).

By monitoring the temperature in your kiln, you can make sure that it is progressing through the stages as you intended. This also allows you to adjust as needed to ensure you are getting the heatwork you expected (that’s why you need to be using cones!).

Keeping a close eye on your kilns firing allows you to identify issues early and take quick corrective action. Failure to monitor and act early when things don’t seem right may result in an over-firing and potential devastating damage to your kiln and its ware.

Although electric kilns themselves do not release toxic gases, the ware being fired in your kiln will! A variety of toxic and corrosive gases are released during firing as the organic material is burnt off.

What you fire determines the composition of the fumes, as certain clays, glazes, decorating products, decals and the like, produce a variety of different gases, including, carbon dioxide, carbon monoxide, chlorine, fluorocarbons, sulphur dioxide, nitrogen oxides and ozone. Heavy metals may also be released if the firing temperature is hot enough and the volatile metals are present.

Good ventilation and air exchange around your kiln is best practice for your health & wellbeing.

Always consider:

• Reduce the number of toxic gases – Consider what clays, glazes and other      items you put in your kiln. 
• Exhaust the kiln – Consider installing an Orton Ventmaster to your kiln.
• Exchange the rooms air – Install a whirlybird roof vent to drag the room air      outside.
• Generate air movement – Have a ceiling fan or pedestal fan blowing on the kiln throughout the firing.
• Dilute the gases – Locate the kiln in the largest possible space, avoid small, closed spaces and corners. Remember, ‘the solution to pollution is dilution’.
• Create Air flow - Open all available windows & doors, including in adjacent rooms to capture any breezes.
• Monitor Air Quality – Affordable air quality monitors can be purchased and installed in your studio, so you can assess the effectiveness of your interventions.

Water vapour is likely the most abundant, and if your ware is not fully dry, this moisture can be absorbed by the hydrophilic kiln bricks and cause electrical outage of your kiln!

Corrosion of your kiln is sadly unavoidable. The cold-hot-cold cycle, plus all the water vapor and toxic gases (sulfur, fluorine, carbon, etc.) coming out of the clays and glazes all combine to create a very corrosive environment for metal. The only thing you can control is the rate at which it corrodes. 

In general, corrosion isn’t covered under warranty because it’s considered a normal part of a kiln’s life, and the speed or extent of corrosion is related to its use and location, not the kiln.

Although the types of clay and glaze used can have a big impact, the most common factor we find with sudden and extensive corrosion is that the ventilation and air movement around the kiln isn’t adequate to off-set the volume of corrosive gases being released.

What can I do to reduce corrosion?

• Reduce the amount of toxic gases – Consider what clays, glazes and other items you put in your kiln. Move to a lower temp with a longer soak, make heatwork work for you.
• Reduce the water vapor – Resist the temptation to not let you ware dry fully before firing. Haste makes waste!
• Exhaust the kiln – Consider installing an Orton Ventmaster to your kiln.
• Exchange the rooms air – Install a whirlybird roof vent to drag the room air outside.
• Generate air movement – Have a ceiling fan or pedestal fan blowing on the kiln throughout the firing.
• Dilute the gases – Locate the kiln in the largest possible space, avoid small, closed spaces and corners. Remember, ‘the solution to pollution is dilution’.
• Create Air flow - Open all available windows & doors, including in adjacent rooms to capture any breezes.
• Reduce environmental moisture – Store your kiln in an enclosed space and / or cover with a BBQ cover. Place moisture absorbing packs in the kiln when not being used. Even in a dry location, dew will form on the kiln if it is located outside.

High humidity or being near the sea all increase the risk of and speed of corrosion.

Brushing excessive corrosion with a wire brush and painting it with a high-temp anti-rust paint may help tidy up the look of your kiln.

Thankfully corrosion doesn’t hurt the performance of the kiln and shouldn’t impact on its 10 year average life expectancy. 

Fire bricks are light weight, have millions of air pockets, are quite fragile and have excellent insulating properties… which is why they are used so successfully in the manufacture of many kilns.

Like everything in the kiln, the bricks will expand and contract with the heating and cooling cycle. The small hairline cracks or fissures are therefore perfectly normal and are to be expected. When the kiln is hot, all the cracks fill in from the expanding brick. 

Not every brick or slab cracks right away, however it appears that all bricks in the kiln, especially the slabs, will crack eventually. Opening the kiln too early will increase the risk of bricks cracking. 

A kiln that has reached a very high temperature or often endures significant heatwork, may show signs of shrinkage, cracking and browning of the internal face of the bricks and element channels.

The good news is, that unless the cracks are structural, even the most severe cracking will not affect the firing performance of your kiln.

It’s good to remember that Kilns are not designed to be airtight, they need to move and breath throughout the firing process. Its normal to sometime see the glow from inside the kiln between the bricks.

Light insulating firebricks are super insulators, but they are very fragile and easily damaged. 

Every firing leads to a process of expansion and contraction – which invariably leads to cracks in the bricks. These are a normal part of a kilns life and allows it to expand & contract when fired and no way effects the functioning of your kiln.

Regular firing to temperatures more than 1270c with prolonged soaks (greater than 10 minutes) increases the amount of contraction or shrinkage. The manufacturer of firebricks (Morgan Refractory) accepts a 1 - 2% contraction in the bricks when used as designed.

However, things happen, and kilns aren’t immune to thermal or mechanical shocks! Therefore if a brick (or part thereof) has become loose, dropped, or fallen, it needs to be secured.

Using pins for repairs whenever possible (instead of lots of mortar) allows the bricks to expand and contract along the pin. Too much mortar limits the brick’s ability to expand during firing and can lead to further cracking and damage.

To repair a brick, follow these simple steps:

ALWAYS turn your kiln off and unplug it from the wall or switch off the power circuit before doing any maintenance.

You’ll need:

- Pliers.

- Brick pins (we can supply these, don’t use normal wire as it will melt!).

- High Temp Mortar if needed (we can supply a small amount of this on request).

1. Vacuum the affected area thoroughly to remove any foreign material, brick dust or small fragments of brick.
2. Secure the bricks in the desired position, using a pair of piers, push in a brick pin to lock the bricks back into its location.
3. Bending the tip of the pin 90° will ensure the pin grips the hot face surface of the brick wall.
4. If the brick has dislodged, apply a sparing amount of mortar to the affected exposed surfaces, then place the piece back in its location and pin as per above.
5. Wipe away any excess mortar or drips. Depending on the mortar type, it will turn white after its first firing (the colour is just so you know where it it!).
6. Make sure no mortar gets onto your elements and if it does, carefully clean it up.
7. Allow mortar to air dry for at least 24 hours, then fire the kiln using a ramp rate of 50°C hr until 300°C, then the ramp rate of your choice. Using a slow ramp will allow the moisture to be driven out slowly and the mortar to bond.

There is no benefit in attempting to mortar over normal expansion or contraction cracks. In fact, this often leads to further cracking and damage, as the mortar limits the brick’s ability to expand during firing.

This can be challenging as the causes may be multiple.

After lots of experience helping our customers, we suggest a systematic process of elimination, starting with a few of the more common things to consider, such as:

1. Could it be user error? Always double check the program you are running on your controller, make sure that someone hasn’t added an extra long soak or changed a value.

• Always double check the program and get a fresh set of eyes to also review. Refer to your controller manual.

2. Are you sure it’s not reaching temperature? Cones are the only way to truly understand the heatwork happening in your kiln.

• If you haven’t used cones, it’s probably time to start. Refer to our FAQ’s on cones.

3. Could it be moisture? Our kilns are made from special fire bricks that have millions of air pockets, which gives them their excellent insulating properties. However, this also makes them hydrophilic - they absorb moisture like a sponge. Moisture is conductive and can create an electrical short circuit. 

• Protect your kilns from ambient humidity, bad weather, dripping condensation and always dry your ware fully before firing.

4. Has your kilns limit switch disengaged? As your kiln heat’s up it begins to expand (above 600°c – 800°c) and if your door or lid is not securely latched closed, the limit switch may disengage. This is a safety feature that cuts power to the elements when the kiln thinks the door/lid has been opened!  

• Always ensure your limit switch is fully engaged, and the door/lid latched shut. Over time your kilns door/lid may need some adjustment of the mechanism to continue to fully engage the limit switch. Refer to the instructions in your manual.

5. Are your elements wearing out?  Element lifespans reduce quickly when frequently fire to high (stoneware) temperatures. Older elements require more power & time to heat than they did when they were new.

• It might be time to purchase a new set of elements, you can find more info on this in our shop and FAQ page.

6. Has one bank of your elements stopped working? Burnt out elements can be caused by a glaze spill, broken ware in the channel, slumped coils, or a corroded electrical connection to the elements.

• Place a strip of white paper behind each bank of elements and fire the kiln to 150°C. Once cooled, check the papers as they should all have scorch marks.

7. Has the Thermocouple failed? If it has been pushed back into the wall of the kiln it tends to read cooler and therefore risks over firing (rather than not reaching temperature) and a failed thermocouple will normally have erratic temperature fluctuations.

• However, make sure it’s not covered in glaze and in the correct position.

8. Could it be your power supply? Voltage drop when the kiln is actively drawing power may stop it reaching temperature.

- Are you using an extension cord? They reduce the amount of power getting to your kiln.

- Have you moved your kiln recently? Not every power outlet has the same ability to draw the same voltage.

- Is another device being used at the same time, that is drawing a lot of your power?

- Is a new development or business in your area impacting on the available power on your supply?

- Are aging elements drawing more power than they did when they were new… and you just don’t have enough?

• If you can’t resolve any of the above then it might be possible to wind new elements with a slightly higher amperage to overcome the voltage drop.

Don’t forget kilns are about heatwork, not just temperature. Consider firing lower with a longer soak to get the results you want… and always use cones!

If you’re still having problems, give us a call to discuss.

Kilns are not designed to be air-tight!

It is completely normal to see a glow or colour between the lid/door and the kiln wall during firing. The amount of heat loss is insignificant and will in no way affect the efficiency or firing ability of your kiln.

It is actually the various light spectrum's that you are seeing (ultraviolet short range & visible medium range).

The longer range infrared spectrum (or Infrared radiation) of light is normally experienced as heat, begins at 400°C and can cause eye damage. Therefore, like you wouldn't look at the sun, its wise to NOT look into a glowing kiln without PPE like a welder's glasses.

To calculate the cost of firing a kiln you will need to know the following:

1. The electricity consumption per hour of your kiln. This will be expressed in Kilo Watts (KW) and can be found on the specification plate attached to the kiln, as well as our specification sheets.
2. The cost of electricity per Kilo Watt Hour (KWH). In Australia it is currently around $0.30 - $0.35 per KWH.
3. The length of your firing cycle.

Assuming you have one of our Fireworker 68 kilns which has a consumption of 5.5KW and you want to fire to 1220c over a 9-hour cycle, the calculation is as follows:

Consumption (KW) x Cost (per KWH) x Firing Time (Hours) = Cost

Example: 5.5 (KW) X 0.33 (KWH) X 9 (Hrs.) = $16.34 per firing.

The above calculation is based on the passage of current through the elements 100% of the time. 

In a firing cycle, the current may only flow 75% of the time, so the above dollar value would be a worst-case scenario, and the likely true cost about 25% less.

A thermocouple is the sensor in your kiln used to measure the temperature. They consist of two wire legs made from different metals, which are welded together at one end creating a junction. This junction (or tip) is where the temperature is actually measured. When the junction experiences a change in temperature, a voltage is created which can then be read by your controller. There are Multiple types:

Type B - Platinum / Rhodium

Temp range: 100° to 1800°

Typical accuracy: 5°C at 1000°C

Suited for high temperature measurements. Unusually, B Type thermocouples give the same output at 0° and 42°C. This makes them useless below 50°C.

Type E - Chromel / Constantan

Temp range: -200° to 900°

Typical accuracy: 1.7°C

E Type has a high output (68 mV/°C) which makes it well suited to low temperature (cryogenic) use. Another property is thatis it is non-magnetic.

Type J - Iron / Constantan

Temp range: -40° to 760°

Typical accuracy: 2.2°C

Limited range makes J type less popular than K type. J types should not be used above 760°C as an abrupt magnetic transformation will cause permanent de-calibration.

Type K - Chromel / Alumel

Temp range: -200° to 1300°

Typical accuracy: 2.2°C

K Type is the ‘general purpose’ thermocouple. It is low cost and popular. Sensitivity is approx. 41 mV/°C. Use K type unless you have a good reason not to.

Type N - Nicrosil / Nisil

Temp range: -200° to   1300°

Typical accuracy: 2.2°C

High stability and resistance to high temperature oxidation makes N type suitable for high temperature measurements without the cost of platinum (B,R,S) types. Designed to be an ‘improved’ K type, it is becoming increasingly popular.

Type R - Platinum / Rhodium

Temp range: -50° to 1760°

Typical accuracy: 1.5°C

Suited for high temperature measurements up to 1600°C. low sensitivity (10 mV/°C) and high cost makes them unsuitable for general purpose use.

Type S - Platinum / Rhodium

Temp range: -50° to   1760°

Typical accuracy: 1.5°C

Suited for high temperature measurements up to 1600°C. low sensitivity (10 mV/°C) and high cost makes them unsuitable for general purpose use. Due to its high stability S type is used as the standard of calibration for the melting point of gold (1064.43°C)

Type T - Copper / Constantan

Temp range: -200° to   400°

Typical accuracy: 1°C

Best accuracy of common thermocouples, often used for food monitoring and environmental applications.

A detailed instruction is available on the resources page of this website.

To changing a K-type thermocouple:

1. Ensure your kiln is either unplugged or turned off from the power point and/or the isolator switch and the breaker is in the OFF position.

2. Remove the terminal cover to expose the electrical connections in the kiln. The

thermocouple will have a yellow 2-flex cable, containing a yellow (+) and a red (-)

inner cables. Connected to the ceramic terminal block on the thermocouple.

3. Withdraw the ceramic connector (the thermocouple is connected to it). Check that

the new thermocouple is no shorter than the failed thermocouple – this will ensure it

sits a suitable distance into the kiln. Unscrew the connections of the compensating

lead to the old thermocouple and insert the new thermocouple into the kiln.

4. K-type thermocouple polarity is:

POSITIVE (+) - YELLOW cable

NEGATIVE (-) - RED cable

You will find a small length of compensating lead attached to the new thermocouple

to assist. You can discard the small length of compensating lead and connect the lead

you have disconnected from the failed thermocouple, observing the correct polarity.

5. Make sure your connection in the insulator block of both the red and yellow inner

cables is solid.

6. IMPORTANT - Replace the terminal cover ensuring that all cables are both AWAY from the kiln case (minimum 1cm) and not trapped between the terminal cover and the base of the terminal box or between the terminal cover and the kiln case. This is

critical as if the compensating lead contacts the kiln wall, then the potential exists

from aberrant readings to occur as the kiln case heats up.

7. Turn your kiln on and run a program ensuring that the temperature in the kiln is

increasing. If you notice a reduction in temperature, please stop the cycle and contact

us. If the controller shows ‘OPEN’ or E000 then it indicates a loose connection.

Repeat steps 1-7 and check for faulty connections or breaks.

If you are after more information on all aspects of electric kilns, we highly recommend you read:

“The Electric Kiln” by Harry Fraser. 

&

"Electric Kiln Construction for Potters" by Robert Fournier.

Both are out of print, but you can sometimes get copies online or in second hand bookshops.

Amps, volts, watts, and ohms are the four basic concepts when trying to understand electrical systems. 

Like how water flows through a hose, electricity is the flow of electrons through a conductor (normally a wire). 

We’ll use a water and hose analogy to explain the concepts.

What Are Amps?

The ampere, or amp for short, is the measure for current. Current is the speed at which the electrons flow through an electrical circuit. You might see amps if you look inside your home's meter box. You'll see different circuit breakers, like 15 amps, 20 amps and 30 amps. The larger the amperage, the more electricity can flow through the circuit.

If you try to run too many appliances on the same circuit, the breaker will "trip" and cut off power to protect the wiring from overheating.

In our water analogy, amps are equivalent to the amount of water flowing through the hose.

What Are Volts? 

Volts is the measure for voltage. Voltage is the difference in electrical potential, or the number of electrons, between any two points in a circuit. Australian electricity runs on 220 – 240 volts, while NZ runs on 230 – 240 volts.

In our water analogy, voltage is equivalent to water pressure. Pressure is the force that moves the water through the hose, just like voltage pushes electrons through a conductor. 

What Are Ohms? 

Ohms are the measure for resistance in a conductor (wire). Resistance tries to slow down the flow of electrons. As our circuits are made up of wires and these wires have a certain amount of natural resistance or friction, this all adds to slowing down the flow of electricity. Therefore, long distances of wire, extension cords and power banks all apply additional resistance.

In our water analogy, resistance is the diameter of the hose. A wide hose has very little resistance and allows water to flow through it quickly, while a narrow hose slows down the water.

What Are Watts?

Power is the rate at which electrical energy is transferred in a circuit and is measured in watts. This is electricity at work and indicates the power it takes to actually do something, whether it's running a vacuum (400 to 900 watts), ringing the doorbell (2 to 4 watts) or illuminating a light bulb (40 to 75 watts).

In our water analogy, power is a little harder to explain. With a hose, you can increase the power by either increasing the amount or the pressure of the water coming out. In an electrical system, you can increase the amps or the voltage.

A kiln element is a piece of wire that is designed to resist the passage of electricity. As current flows down the wire, the resistance impedes the flow and so causes the wire to heat up. Element lifespan is primarily dictated by the temperature to which you fire. The higher the temperature, the shorter the lifespan. 

As a rule of thumb Kanthal A1 elements will last about 500-600 firings to 1150c, 200-250 firings to 1220c, 120-150 firings to 1280c and no more than 75 to 1300c (1300c being the absolute maximum safe operating temperature of our kilns). These numbers come from Graph 1. In “Electric kiln construction for Potters” by Robert Fournier – a great book to read if you are a kiln freak! (I think they are a bit optimistic!) They are a probably best case scenarios and are meant as a guide. They assume that elements just wear out. 

Unfortunately, impact to the elements in packing, glaze splatter or noxious gases will shorten the lifespan further. You may notice that as your elements age, the kiln fires more slowly or struggles to get to temperature. This is a known characteristic of Kanthal wire. It is vital that you keep the element channels always clear of debris – a small piece of broken kiln brick or broken pot that jams up against an element can cause a local “over-heat” and burn out an element. Similar situations can occur with kiln wash or glaze getting onto elements. 

Our recommendation is that you carefully vacuum out all element channels before each firing and place glazed ware a minimum of 4cm from the elements – a little bit of care can make a big difference. An important feature of Kanthal wire is that after firing the wire will build up a layer of Aluminium oxide on its surface that protects it from attack by harmful gases. It will take 2-3 firings for this layer to build up. It is not a bad idea to therefore perform a couple of bisque firings with new elements (either a new kiln or replacement elements) prior to a glaze firing. The reason for this is that glazes will tend to liberate significantly more corrosive gas than does bisque ware. 

We NEVER recommend reduction firing in an electric kiln

Elements leaving their channel over time is not uncommon. Cold elements are brittle, however when red hot they become soft, so if the element has slowly moved, gravity can take over and the hot element can begin to sag.

Looks can be deceiving, elements that are sagging, stretched or misshapen may be unsightly, but they may still be functioning fine. You can use a multi-meter to check their condition (a +/- 10% variance from the elements normal is a sign replacement may be needed soon). 

Once an element leaves the wall of the kiln, they are not only at risk of being broken during loading, unloading but can also take up valuable space in your kiln. Therefore, if the element is still in good health, then repair may be worth a try before splashing out on replacement elements!

Before doing any maintenance on your kiln, you must consider safety:

• Consider ventilation, flammable materials, appropriate personal protective equipment.
• ALWAYS turn your kiln off and unplug it from the wall or switch off the power circuit.

Re-seating elements:

You’ll need:

- Needle nose pliers.

- Small blow torch (you can buy these at your local hardware shop).

- Element pins (we can supply these, don’t use normal wire as it will melt!).

1. Gently vacuum out the kiln and element channel. 
2. Remove any element pins you find in the empty channel (you can reuse them).
3. Use the blow torch to heat (turns red) the length of sagging element plus a few centimeters each side. The whole length may not be red all the time, but by sweeping back & forth you know it’s hot and less brittle.
4. Taking your time and alternating between both ends, while the element if glowing hot use the pliers to gently reshape and reposition the element.
5. Check that no coils of the element have become pinched together. If so, simply re-heat and stretch out the coil as necessary.
6. Once you’re happy its back in shape/place, use the blow torch to re-heat the entire element your worked back to glowing hot on last time.
7. Once cooled, gently use the pliers to push the element pins in to keep the element in place.

Unless it's a kiln purchased through us, or one that is known to us, you'll need to send through a detailed drawing with the following information:

1. If a specification plate is visible, notate the current drawn, kW rating and voltage of the kiln. Also the model or serial number if available.
2. length of the elements and the number of grooves it occupies.
3. Indicate whether tails are twisted or single and the length.
4. Measure the outside diameter of the coils.
5. Measure the thickness of wire – use a vernier for accuracy, as the nominal difference between wires can be 0.1mm.

There is a handy Element Order Form to make it a bit easier.

We wind our own elements and can typically have them made within a few days of a confirmed order, assuming you have provided all of the required information.

A detailed instruction is available on the resources page of this website.

1. Safety is the first concern. Either unplug the kiln or isolate on the wall and also on the mains distribution board. If a locking device is provided, lock the switch off. In a domestic environment, advise the family of what you are doing, in particular to the switches that have been turned off.
2. All kilns are different, so these are general instructions only.
3. Your new elements should arrive stretched with segment elbows in place. 
4. Remove the covers exposing the connections to the elements. Elements are manufactured to ensure the correct amperage, therefore they should never be cut and only used as supplied.
5. Make a careful note of how the elements are connected (take a photo with your phone) and then disconnect all the wires to the tails of the elements, marking them appropriately for the positions to which they were attached. 
6. Old elements tend to  become very brittle and will probably break once you attempt to remove them from the grooves. Special care must be taken to protect the grooves in the bricks from being damaged.
7. Place the new element gently into the grooves to assess the fit – the element must be “seated” well into the groove – this may require removing the element during the fitting process to stretch it a bit more – make sure you stretch along the length of a segment to get an even stretch over the segment length. Sometimes you may need to squeeze the element coils closer together if the element is too long. There should be a smaller vertical groove in the brick between each large horizontal groove, this is where you will fit the segment elbow. 
8. If the elements were pinned previously then it would be recommended that you also pin the new elements in similar positions. Generally, 5-6 pins are used per segment. Use a pair of pliers to hold the pins firmly and then push them into position – avoid using the previous element pin positions.
9. You  will need a bolt cutter to trim the tails of the elements, which are  normally supplied over-length. Cut them to the same length of the old ones. 
10. Re-attach all your wires making sure that you fasten the wires to the element tails very firmly as a loose connection can cause a 'hot joint' and impact your kilns functioning.
11. If you are equipped to check the 'current draw' or if you have a friend who is, it's a good idea to compare the specified current versus the elements that have just been replaced. 
12. Replace all the covers. 
13. Then you may need to oxidize the elements – this is achieved by firing the kiln empty to 1100ºC and soaking for 3 hours with the bungs open. This process ensures that the elements generate an oxide layer, which  protects them from the atmosphere. 
14. If you do not feel confident in fitting an element we strongly recommend that you engage a kiln technician to change your kiln elements.

The two important things to fully understand are HEATWORK & CONES.

Mastering your kiln goes beyond relying on the controller to measure temperature and time alone. Success involves understanding the kiln itself, its unique characteristics and nuances in heat distribution and heatwork. 

This knowledge enables informed decisions and adjustments, blending technical precision with a nuanced understanding of the kiln's behaviour and performance to achieve the firing results you want.

Firing ceramics in a kiln is a bit like cooking. You can set your oven on a very high heat and cook your dinner in just a few minutes, or you can cook it for longer at a lower heat. Either way, you end up with a cooked dinner.

Heatwork is the combination of time and temperature. Our imaginary dinners received the same amount of heatwork, even if they were cooked at different temperatures and for different durations.

Pyrometric Cones are still a very important tool in a potter’s armoury and the only definitive measure of heatwork. 

Without a cone in your kiln you will not know whether your pottery reached temperature unless it is badly under fired. It is useful to bench mark good firings with cones and to save these results.  If you are experiencing unsatisfactory results, cones will quickly tell  you whether the kiln or glaze is at fault. 

• If the fired results of cones significantly differ to your benchmark, then look to your kiln for the cause. 
• If the fired result of the cones is the same as your benchmark, look to your glazes and or clay body for the cause. 

It is useful to place cones next to your thermocouple and in areas where you get your best results, as these are your litmus tests.

We have created a quick reference guide that you may find helpful.

Thermocouples only measures temperature, and they do so only in the immediate vicinity of the junction (tip). Pyrometric cones measure “heat work” – which is a measure of the impact of time and temperature.

1. Cones consist of a mixture of carefully controlled ceramic materials that are designed to give a graduated scale of fusing temperatures. The most commonly available cones are manufactured by the Orton company, and they provide a chart that provides the fusing temperature with a corresponding cone number.
2. Orton Cones are frequently shipped in "Compacts" (2 Connected Cones) to improve stability and prevent damage. These cones need to be separated before use by gently snapping them apart. A video of how to do this is here.
3. Cones are mounted either in a specific refractory cone holder or alternatively embedded in a wad of clay, with each cone placed to the same depth and at an angle of 15° to the vertical. This is assisted by a slant on the base of the cone.
4. A series of three cones is standard, the cone placed on the far left indicates 20° below the required temperature, the middle cone indicates the required temperature and the cone to the right indicates a temperature 20° above the required temperature. The collapse of the first cone serves as a warning that the required temperature is being reached, whilst the second cone collapse indicates the correct temperature. The third cone, or “guard” cone should remain upright as it serves to warn of potential over firing. The fusion point of any cone is indicated when the tip of the cone touches the base on which the cone is mounted.
5. It is a good idea to place cones in several locations in your kiln so you can get a feel for the hot and cold spots. This is more important in larger kilns. Cones also provide a guide as to the accuracy of your thermocouple. 
6. Every kiln is different, and it may take some time to learn the idiosyncrasies of your kiln!
7. Orton have a treasure trove of resources and videos available to help you learn about cones and how best to use them.

We have created a quick reference guide that you may find helpful.

Mixing the glaze from powder for dipping, pouring, or spraying: 

1. Wear a suitable protective mask.
2. Sprinkle the glaze powder into a suitable container of water. 
3. We suggest you start with a 1:1 ratio, (i.e. 1 kg of powder to 1 litre of water).
4. Stir thoroughly.
5. Leave to settle overnight and skim off any surplus water. 
6. Stir again and then sieve through an 80 mesh (or finer) sieve.
7. If necessary, add small amounts of water to achieve your desired consistency.
8. We suggest a consistency a bit thicker than Full Cream Milk (like pouring cream) for a dipping glaze, however you may want it thinner for spraying or thicker for pouring. 
9. Your glazes may start to settle during use, you should regularly stir or agitate during your dipping / pouring / spraying session. 

Note: When adding water: add small amounts cautiously and stir well between each addition until you reach your desired consistency.

The more water you have in a glaze, the less solid particles there are (proportionately) to stick to the bisque! Less solid particles means a thinner glaze application. Each glaze (and each potter) will have a different “ideal” ratio of solid particles to water. 

Liquid glazes can settle out over time. They sometimes set hard at the bottom of the container, making them difficult to re-mix. To overcome this a flocculent or anti-set solution should be added a little at a time. 

Epsom salts are a good flocculating agent. Adding 1% saturated Epsom Salt solution to your glaze mix with thorough stirring will re-suspend your glaze mix. 

Some common glaze problems (or perhaps the effect your looking for) and their solutions as excerpted from Robin Hopper’s book called 'The Ceramic Spectrum' and from our wonderful glaze technician Sorrel from 'Glaze Craft Ceramics':

Crazing is the most common glaze defect, and normally the easiest to correct. In both crazing and shivering the eradication of problems relies on matching the thermal expansion characteristics of both body and glaze. Common factors that increase the risk of crazing include:

• Sudden temperature and humidity changes.
• Moisture getting into the glaze.
• Wares being bumped or knocked repeatedly.
• The kiln heating or cooling too quickly, where the glaze will shrink quicker than the body of the ware.
• The wrong clay body for the glaze. High silica content will cause crazing.

Shivering is the most problematic of glaze defects, particularly in any functional ware, since slivers of glaze from the edges can drop into food or drink. These slivers are usually small, sharp, jagged-edged pieces that detach themselves from the body. It tends to happen because the thermal expansion of the body is more than the glaze's.

• The best way to resolve this is to try another clay body of the same fired colour and temperature range, to get a better ‘glaze fit’.

Crawling is caused by a high index of surface tension in the melting glaze. It is triggered by adhesion problems, often caused by bad application. It occurs where a glaze does not fully adhere to the surface of the clay. Crawling is more common in matte glazes than in fluid ones. Crawling can also occur when one glaze is applied over another, particularly if the first is allowed to dry out completely before the second application. 

• Follow this link to read a comprehensive article about crawling.
• The best way to correct crazing is to change to a different clay body, which better fits the glaze or try increasing the firing temperature.

Pitting and Pinholing are the most annoying and difficult glaze defects to cure. They can be caused by a badly controlled firing cycle, the glaze composition, or can originate with the body, particularly highly grogged clay bodies. The following remedies should be tried to cure pinholing or pitting:

1. Apply the glaze less thickly
2. Make the glaze more fluid to alter its surface tension.
3. Lengthen the firing cycle to give the gases longer to escape.
4. Increase the maturing temperature of the glaze.
5. Hold the kiln at the glaze maturing temperature for a longer soaking period.
6. Cool the kiln down more slowly.

Blistering and blebs are caused by the escape of gases from the clay body or the glaze, usually the result of either an excessively thick application of glaze or incomplete clay preparation (wedging, blunging, etc). Therefore the solution is prevention:

• Make sure the clay is well prepared.
• Has the ware adequately matured and lost most of the escaping gases in the bisque firing.
• Increase the ventilation of the kiln and its environments.
• Make the glaze more liquid or apply less thickly.
• Review your clay and glaze choices.

Our partners at Potterycrafts in the UK also have a helpful handout that includes pictures, 'Glaze Faults and Remedies' which you can download from our resources page.

The Brush-on glaze contains a medium that allows it to be stored in a liquid form and allows it to be applied smoothly with a brush (whereas the powders don't). Its good practice to stir the glaze well and you should notice in become nice a creamy. Shaking the glaze vigorously can change how the glaze reacts, so its not recommended.

The Powder glazes are designed for dipping, spraying or pouring. You have more flexibility in regards to the volume and consistency you want to achieve your desired results. However, you may not get an even application if brushed on.

YES!

Some people fire a single piece 3, 4 or even more times until they get exactly what they like. 

Re-glazing is also useful in repairing small chips or cracks in the pottery along with fixing a glaze problem. Layering new glazes on old glazes can also can add an interesting texture & depth.

The only rule in multiple firings is that you can't re-fire at a hotter temperature than a previous firing, or you will burn off the lower temperature glaze.

The short answer is “yes”. However underglazes are not like ordinary paints. In the firing process they undergo a chemical reaction & change colour (Compare Dark Blue in its raw and fired states). 

The safest process would be to mix a ratio of two colours together and then do a test firing of that mixture, before you commit yourself to applying it to a precious piece. 

Except for the Metallic Black, all of our other glazes are food safe when used as instructed and fired to maturity on an appropriate clay body. 

Some people recommend the 'Lemon Test' - squeeze on some lemon juice, and leave the lemon wedge on the piece of ware overnight. If there is no colour change then leaching hasn't occurred and your pieces are suitable for functional use.

Be sure to anchor your 3D glaze by pushing down on it gently and squeezing at the  same time, a bit like cake icing! If they tend to lift when drying, simply wet your finger with water and press gently on the 3D glaze.

Always store your kiln shelves on their end. Never store kiln shelves flat and certainly never flat stacked on top of each other. Doing so significantly increases the risk of shelves cracking.

Always use kiln wash to minimise the risk of glaze runs ruining a shelf. Regularly scrape off and reapply your kiln wash.

Always flip kiln shelves when using them in the kiln. This will minimise warping. All shelves will begin to warp, particularly at temperatures exceeding 1260c. Thicker shelves minimise warpage, but may also be excessively heavy, so making loading them difficult. The best solution is to use shelves that you can manage easily and regularly flip them. This may require the application and sanding of kiln wash on alternative sides of the shelf (if the underside of a shelf is kiln washed, then you risk having flakes of kiln wash drop onto your glazed ware, causing damage, so best to remove and clean the underside).

Always make sure you kiln shelves are bone dry when using them. If there is moisture in the shelves then as they heat they are likely to suffer expansion cracks.

Always use moderate ramp rates in the initial stages of firing up until 200c (generally rates below 120c/hr are safe). Fast ramp rates may cause rapid expansion of the shelves, leading to cracking. The same applies when cooling your kiln. Avoid rapid cooling below 250c as sudden drops in temperature will cause thermal shock and cracking.

Always use 3 props to support a shelf. This is the most stable configuration. Ensure the props are placed in line vertically, so that the load of each shelf is passed down the props.

Always check your shelves carefully when packing your kiln. If a shelf is showing signs of cracking DON’T use it. Better to replace a suspect kiln shelf than risk a collapse of furniture and ware in the kiln.

Sadly, kiln shelves don’t last forever, but by sticking to the above pointers you will prolong their life. The higher you fire, the more likely you are to experience warping and cracking of your shelves even with the best care.

We also offer not only traditional Cordierite-Mullite shelves but also Oxygen Bonded Silicon Carbide (OBSiC) and Nitrogen Bonded Silicon Carbide (NBSiC) shelves. 

Batt: A thin slab of wood, plaster or plastic used to support ware during shaping, so you can move it without damage. Some people also refer to kiln shelves as Batts.

Bisque Firing: The first firing of your ware, changing it from clay to pottery. 

Buff Clay: A versatile type of clay, that depending on the firing temperature can be used at earthenware or stoneware. Buff refers to its colour – yellow / brown.

Candling: A very low and slow firing of the kiln to slowly dry out your ware.

Coiling: Method of building up a clay wall by layering coils (or ropes) of clay on top of each other.

Crazing: When the glaze has multiple little cracks due to high tensile stress during firing. This may or may not be the finish you were after.

Earthenware: Matures at approximately 1060°C to 1100°C – Can be quite porous so normally can’t be used in a dishwasher or microwave. Handy for plant pots as it slowly wicks moisture. Terracottais a form of earthenware.

Fettling: Removing the unwanted excess clay on a piece of greenware, normally while leather hard.

Glaze Firing: To convert the glaze that been applied to the work, into its ‘glassy surface coating’.

Glaze: A coating that when matured forms a glassy finish on the ware.

Greenware: Ware that has not yet been fired.

Leather-hard: Greenware that has partially dried to a point where all shrinkage has stopped.

Maturity: When your ware reaches its desired effects in the kiln through the effect of heat work (read the FAQ specially on heat work).

Mid-fire: A popular and commonly used clay that matures at approximately 1200°c to 1240°C.

Oxidation Firing: When you have more oxygen than fuel in the kiln. This is the standard atmosphere in an electric kiln.

Pinholes / Spangling: Faults in the surface of the clay or glaze, resembles pin pricks.

Porcelain: A super fine clay that matures at approximately 1220°C to 1300°C – Harder to throw with and more costly to fire due to the heat requirements.

Raw firing: Applying glaze to ware that has not had a bisque firing and firing both together.

Reduction Firing: When you have more fuel than oxygen in the kiln. This can be achieved in solid fuel burning kilns (wood, gas etc). It’s NOT recommended to try and achieve a reduction firing in an electric kiln.

Slip: A liquid form of clay that can be used for decorating or slip-casting (putting it into moulds to get complex shapes etc).

Stoneware: A high-fire clay that matures at approximately 1260°c to 1300°C – very durable and non-porous. However, given the impact of this high temps on electric kilns and element life-span, many people are moving to modern Mid-Fire Clays that can achieve the same results at a lower temperature.

Turning: Trimming and shaping ware while in the leather hard state.

Ware: Is what we call objects that are made from clay and happen to be one of the earliest human inventions!

Wax resist: Using liquid wax on ware where you don’t want glaze to be repelled (part of the design or the bottom of ware so it doesn’t stick to the kiln shelf).

Wedging / Kneading: Preparing clay through working it by intermittently throwing on a bench, needing & cutting. The intent is to remove any air bubbles and make sure the clay is a uniform consistency.

Mix up some kiln wash with water until it is the consistency of milk. Its better to make it too runny than too thick, otherwise it might crack off your shelf before you even put your shelves in the kiln! 

Brush this runny mixture onto only one side of your kiln shelf with a soft brush and allow to dry. You will still see some of the shelf colour through the kiln wash. Apply a 2nd coat to the shelf and allow it to dry. You may need to apply a third coat.

You will know when you have applied enough when you can no longer see the colour of the shelf through the kiln wash and your shelf appears white. Once you have done this, leave your shelves to dry overnight.

The shelves will have soaked up water with each application of kiln wash, and you don't want to fire damp shelves in the kiln as they may crack. Therefore, fire your shelves 1st in a bisque firing – i.e. fire them slowly, rather than  fast. 

That way you will be able to use your shelves for many firings - up until the kiln wash starts to crack off the shelves (10 - 20 firings if you look after them). When needed, scrape it off the old kiln wash (we have Rub Bricks to help with this), turn your shelf over, and apply new kiln wash to the other side of the shelf.

Flipping your shelves periodically helps prevent them from sagging.

If you apply kiln wash to the underside of your shelves, or don't remove old kilns wash once you flip a shelf, when it starts to peel off it may fall on your pieces in a glaze firing!

1.  Before use, make sure that there is no dried clay in the clay barrel.
2. Insert the required die between the barrel and the base of the extruder and tighten with supplied wrench.
3. Wedge your clay well and shape it roughly to fit the barrel of the extruder (water content should be approx. 20%). 
4. Place the clay in the barrel of the extruder (To make cleaning easier, consider putting the clay in a plastic bag or cling wrap. Cut an opening in the bottom and place in the barrel).
5. The clay should not exceed 2/3 the height of the barrel.
6. Lower the pressing plate into the top of the barrel and ensure it fits securely. 
7. Pull down on the lever with slow, smooth force. As the clay in the barrel compresses, the lever position will come down. 
8. Extrude your clay and clean up after use.

We started this business in 2020 to provide, reliable, versatile, and solid kilns & pottery equipment at a price point that is more affordable than many other suppliers. Here are a few pointers to consider.

1. Kilns generally consist of a range of generic parts that are readily available from any kiln manufacturer, or kiln repair technicians. The bricks are generic, so is the element material as well as the contactors (they control the current from the control box to the element). The only unique item on a kiln is the controller. We supply a range of controllers suitable for the type of kiln chosen, however it’s possible to chop & change controllers or add a new controller to an old kiln.

2. We carry a full range of spare parts specific to the kilns we supply and are happy to provide as required. We also wind Elements for all our kilns, and any other kilns provided we have the specifications (check out the FAQ on ordering elements above).

3. Fortunately, there are no moving parts in kilns, however they continually expand & contract with each firing! Keeping on top of your kiln’s maintenance prolongs the life of your purchase. By taking care of the lining, particularly in loading and unloading, your kiln should last many, many years. There are several very experienced kiln technicians that can perform repairs if required.

4. We offer a 2 year warranty on our kilns. This covers any fault in manufacture only, not wear and tear or the ubiquitous brick expansion cracks etc. Elements and thermocouples are also considered consumables as their lifespan is dependent on use (like tyres on a car).

Surprisingly we hear this a fair bit, however our products are not cheap, we work hard to make sure they are affordable! We keep our margins small, over-heads low and seek out functionality & reliability above how things look!

Our kilns are manufactured by some of the worlds most respected and experienced kiln and furnace manufacturers in the United Kingdom, Holland & South Africa. 

Other products are sourced locally or imported from New Zealand, Taiwan, USA, China & India. We have been able import them at what we think is a fair market price. 

We are generally open Monday to Friday from 9am to 5pm and occasionally on Saturdays mornings for special collections. We are a functioning factory, warehouse and shop, so if you need some advice or support, it's best to call us prior to coming to ensure we have the time to help you with your needs.

A after-hours collection box can be made available if you are unable to attend during normal business hours. This service is always at your own risk and does have some size limitations, so we ask that you contact us to discuss if you'd like to consider this after-hours collection or drop-off option.

Once we receive your order through our website, we will double check with you if necessary for things like your electrical capacity and also what sort of freight / delivery / collection (for larger items) you prefer. 

We will then email you an invoice which includes a quote for shipping.

• If the item is in stock, its available once payment has been received.
• If the item is not in stock, you will be allocated one in the next shipment, once the deposit has been received.

Freight costs can vary dramatically. Prices are quoted on the assumption of unimpeded access (lawns, pebbles & stairs can be problematic) and is normally delivered by a tailgate truck & pallet jack. Any deviation from this may incur additional costs from the freight company, so please inform Fired Up Kilns ASAP to discuss alternative options. 

Collecting from your local depot often saves you a considerable amount, all of the local depot sites can be found here. Delivery to a business with a forklift reduces the cost yet again.

Items we freight, we insure. But if you organise your own freight then we highly recommend you investigate having the items insured for transit damage / loss. If you believe your shipment is incorrect or has items damaged or missing, please complete the 'Damage Form' and call / email us immediately and await our instructions.

Always take photographs of any concerns or damage to products and its packaging. This will be essential evidence if an insurance claim is required.