Electric Kilns Electric Kilns
help, support, and tips or larger kilns at paragonkilns.co.uk or tumblers at electrictumblers.co.uk
kilns
kilns
support
clays
materials
tools
extras
sales
Paragon KM14D Knife-Making Kiln K-Type Thermocouple Electro-Mechanical Relay Fire Bricks
UK To EU Plug Adapter
Ceramic Block
Corfe Castle In Dorset
Cherry Heaven Shop In Corfe Castle
Ceramic-Fibre Cloth
Bullseye Kiln Paper
CR1 Professional Motor Base
CR2 Professional Motor Base
CR5 Professional Motor Base
Large Rubber Drum 2000gm Open
Digital Pyrometer
Cherry Heaven Digital Alarm-Timer
The Dremel Engraver
The Dremel Engraver In Use
EU Plug
Fire Extinguisher
File Set
File Set
Glare-Resistant Glasses
Heat-Resistant Gloves
Cutters
Flush Cutters
Flat-Nose Pliers
Pointed-Nose Pliers
Bent-Nose Pliers
Round-Nose Pliers
Knife Set
Knife Set
Large Plastic Drum 700gm Closed
Large Rubber Drum 950gm Closed
Large Rubber Drum 950gm Open
MiniDrill
Digital Multimeter
Magnetic Polisher
Magnetic Polisher
Magnetic Polisher
Magnetic Polisher
3M HEPA Dust Mask
Mains Tester Screwdriver
Magnetic Polisher Pins
Magnetic Polisher Pins
Protective Safety Glasses
Ring Guage
Bartlett Sentinel Touch Screen
Small Plastic Drum 700gm Closed
Scriber
Shot: Balls And Planetoids
Shot: Pins And Rods
Soldering Iron
Paragon SC2 Shelf Kit
Small Plastic Drum 700gm Closed
Small Rubber Drum 510gm
Stainless Steel Containers
ST4 Professional Motor Base
ST7 Professional Motor Base
ST8 Professional Motor Base
SEtch on Art Clay By Larissa Johnson
SEtch on Polymer By Larissa Johnson
South-West Of England
Rotary Tumbler Kit 1
Rotary Tumbler Kit 2
Rotary Tumbler Kit 3
Rotary Tumbler Kit 3 With Two Drums
Rotary Tumbler Mini With One Drum
Triblets
Ultrasonic Cleaner Kit 1
Ultrasonic Cleaner Kit 1
Ultrasonic Cleaner Kit 1
Ultrasonic Cleaner Example
Cherry Heaven USB Loudspeakers
UK Plug
Vermiculite
Large Rubber Drum With Vanes Open
The AX-4 Digital Controller
MiniKiln Closed
Paragon BlueBird Open
Lauscha by Carrie Fertig
Activated Charcoal Granules
Caldera A Closed
Caldera AB Closed
Fusion CS14D Open
Fusion CS14SB Closed
Caldera XL Closed
FireFly A Closed
Fusion-7 Open
Fusion-CS16D Open
Fusion 8 Open
GL18ADTSD Open
HT-14D Closed
Janus 1613 Open
KM14D Open
Paragon-Orton Vent Master: Unassembled
Paragon-Orton Vent Master: Suction Cup
Pearl 18 Open
PMT21
Potter & Brumfield Relay
SC-2 Black Open
SC2 Open
SC2B Open
SC4 Closed
Sentry Xpress 4.0
Sentry 2.0
Sentinel
SC-2 Pink Open
SC-2 Turqoise Open
SC-2 Purple Open
The Paragon ST-8 Table
TNF 1613 Closed
GL Table
Xpress Top Row Bricks
USB Plug
Xpress E-12A Open
Xpress E-12AB Closed
Xpress E-14 Closed
Xpress Q-11A Open

Over the years, we've been sent lots of ideas, suggestions, and tips. If you have anything to add that would help other kiln owners, use the mail link below the menu bar near the top-right of any page.

Please keep your suggestions general in nature. There are specialist internet resources, books, and courses, about Art Clay, PMC, annealing, ceramics, glasses, enamels, polymer clays, raku, stained glass, casting, fusing, sagging, and slumping.


Before we look at specifics, I'll begin with a section about how your kiln works and what you can do to check for possible faults. After that, skim through the sections and read those that interest you. If you want to ask anything, mail or call.

SYSTEMATIC FAULT FINDING
Kitiki Digital Multimeter

How A Kiln Works.

A kiln, even a large one, isn't a very complicated thing, so there's no reason to be anxious about using it: it's little more than a big toaster.

It's just an insulated box with an electronic programmer and some red-hot elements. Inside, there's something called a thermocouple that measures the temperature and something else called a relay which is just a big switch. The thermocouple talks to the programmer, and the programmer talks to the relay telling it to turn the elements on or off. The programmer is similar to the one that controls your central heating: although it's a lot simpler to set up.

Like most electronic things, the programmer is a low-voltage device so there's no mains just behind the buttons. And, like every electrical thing with a metal case, the whole thing is earthed so that, in the very very ulikely event of a serious fault, the plug fuse and the mains fuse in the fuse box will pop.


When the kiln is switched on, the display usually shows 8888. This checks that all four digits, and all the parts that make up the digits, are working.

After a few seconds, the display will show a programmer version number: something like E-1 or F-1. If it shows PF there was a power failure duruing the last attempted firing. To clear this, press Start/Stop. Usually, a power failure message means that the kiln was turned off whilst doing something. It doesn't mean that the building's power supply failed.

After a few more seconds the display will alternate between IDLE and the current room temperature. If the temperature looks very wrong, the thermocouple has probably failed. Remember that the thermocouple is in a red-hot kiln and will eventually corrode: it won't last for ever.

If the kiln is at room temperature, reach inside and squeeze the thermocouple tip gently. The display should show the temperature increasing to around normal skin temperature.


Set a programme: full speed to 600°C then hold for three minutes. Start the programme, stay by the kiln, and write down what happens. After a few seconds the relay, an electro-mechanical switch, will click, the elements will come on, and the temperature will start to increase. The thermocouple checks the temperature and, depending on the sequence you've chosen, the programmer turns the elements on or off to control the heating rate, the target temperature, and, eventually, the cooling rate. When the sequence is complete, the kiln beeps.

If there's a second click almost straight away, or the displayed temperature doesn't increase, the relay is probably faulty and isn't staying on: so the elements can't heat up. It's less likely that the elements have burnt out, but we'll look at this later.

Because the programmer was set to heat up at full speed, the relay should stay on until around 600°C. Then it will click off and the hold time will begin. It will probably click on and off a few more times to keep the temperature more or less constant. After the hold time has expired, it will click once more, the relay will be off, the elements will be off, and the sequence will have completed. You can turn the kiln off if you wish, unless you want to watch the temperature fall.

If the sequence completed, the kiln would appear to be working correctly. If it kept rising well above the 600°C, the thermocouple might be faulty and not reporting the correct temperature to the programmer. Or the relay has stuck on. However, relays default to off, so sticking on is rare.


Further checks need to be done by someone who has a multi-meter, similar to the one in the photo above, and is confident about working with mains voltages. You can buy a multi-meter in the on-line shop. If you're only half confident, call one of our engineers when you have the multimeter and you're by the kiln.

Although these notes apply to a Paragon SC2, the procedures are similar for other models. Unplug the kiln, stand it on a blanket so that nothing gets scratched, remove the back, lower it down, and do a visual check that all the wires are connected and there are no signs of sparking or burning.

In the factory, the casing screws are put in tightly with an electric screwdriver. When removing them, use the correct-size screwdriver. As with any screw, the wrong size screwdriver can damage the head, making it difficult to remove. You might need some pliers just to pull the loosened screws out.

Identify the two thin wires, red and yellow, that come from the thermocouple and go the programmer, and the two thick wires that come from the relay and go to the elements. There are usually brass connectors joining the thick wires to the element ends.

Set the multimeter for resistance, probably a 200 ohms setting, and measure the resistance of the elements. Do this carefully as there may be two elements joined together. The reading will be 15 - 60 ohms, depending on the kiln. If the multi-meter says zero, the element has failed.

The next part is done with the kiln on, so needs extra care. Unplug the kiln, set the multimeter for AC voltage, probably a 500 volt setting, and tape the leads onto the brass connectors on the element ends. Plug in the kiln, and start the programme we used above. As soon as the relay clicks, the meter should show mains voltage, around 240V in the UK, and the kiln should start to heat up. If it shows zero, the relay is not switching on: even if you heard it click.

Switch the kiln off, unplug it, and un-tape the multimeter leads. It's very important to be careful with the leads as, if one end is touching a live voltage, the other mustn't touch the metal case, other components, or you.


Remove the screws holding the programmer in place, and gently ease it out of the metalwork. All the connectors should be firmly on, especially the thin red and yellow thermocouple wires that are held in push-down connectors. Check that they're not loose or touching each other.


Many kilns have more than one element, and some have more than one relay. If you can run a programme, open the door and the lid briefly and make sure that all the elements are glowing. If one or more aren't, the kiln probably won't reach the temperature you've set.


So, the most likely problem will be that the thermocouple has failed, then the relay, then the element. You can talk to a technician, although basic checks, adjustments, and repairs are quick and easy, needing little more than a PoziDriv screwdriver. You can watch on-line service videos: use the main-menu link below the menu bar near the top of the page, then choose tee-vee, then choose from the guide.

GENERAL SAFETY
Medical Care

Safety And Public Liability.

However careful you are, kilns, torches, drills, files, knives, and chemicals, are all potentially dangerous. If there's an accident, you won't have time to find out what to do, so think about safety issues before you start work. Generally:

If you're working with electric kilns, gas hobs, and butane torches, there's always a risk that you'll have an accident with hot materials or set fire to something.
It's important to have a fire extinguisher, nearby. Read the instructions as soon as you unpack it, learn how to treat burns, buy a basic first aid kit, and fit a smoke alarm.

If you're using cutting, drilling, or abrasive tools, wear safety glasses: you've only got one pair of eyes. If you work with hot metal, glass, beads, or ceramics, wear glare-resistant glasses and heat-resistant gloves.

For accessories, options, and tools, such as extinguishers, safety glass, hot glasses, and hot gloves, use the shop link below the menu bar near the top-right of every page.

THE KILN WORK AREA

The Kiln Work Area.

Kilns need to be in an open, well ventilated space, not in a cupboard or closet. They should be at least 300mm from any vertical surface that could burn, and, if you have two kilns, at least 500mm apart. Never put insulation around a kiln to try to conserve energy: the wiring and the programmer will overheat, and may burn out.

Table-top kilns either don't need a stand or come with 50mm high rails. Most kilns have plastic non-slip feet so don't need to stand on anything else. Although, if the worktop is easily marked put the kiln on a rectangle of wood.

If your kiln comes with a floor stand, don't abandon it and put the kiln on a flat surface as this will prevent the natural flow of air around the kiln and change it's firing characteristics. If it comes with a vent, this needs to connect to the outide: not another room.

Small kilns, such as the SC series, can use a regular mains socket and stand on a worktop or table, Large kilns, such as the Janus 27, need a dedicated circuit, and should stand on the floor: a floor not a carpet.

If you stand your kiln on a table with castors or wheels, you need to wedge the wheels or use a wheel lock. Otherwise, if you knock the table, your work may fall over.

If the room is protected by a fire-prevention sprinkler system, don't position the kiln under a sprinkler or a heat sensor: the whole system might come on and flood the building. Ask about getting a smoke sensor instead of a heat sensor.

Make certain that no one can touch the kiln who doesn't understand what a kiln is and the sort of temperatures used during firing. If inexperienced people are around, make sure they understand that the kiln might be hot. Opening the door mid-sequence will cause a sudden drop in temperature: glass pieces may crack.

Although kilns have automatic digital programmers and built-in safety cut-outs, don't leave your kiln on if you leave the house or go to bed.

If you're using your kiln in a garden shed or a garage, check that you don't have paints, volatile inflammable solvents, petrol, a lawnmower, or a car, in the same space. And ventilate the area.


If you use your kiln at home, check your building and contents insurance: a standard policy may not cover you against an accident arising from using a kiln, especially if it's used by a business.

If you're running courses at your home or workplace, you may need public liability insurance. And check that you have complied with local health and safety regulations and change-of-use planning consent. These might include providing protective eyeware, fire extinguishers, first-aid training, disabled access, a bathroom, and fire exits.

VOLTS, AMPS, AND WATTS
A Domestic Consumer Unit

Electricity.

If you avoided a technical education, there are three commonly-used electrical measurements: Volts, for example 230V, is the pushing force. Amps, for example 5A, is the amount being pushed. Watts, for example 60W, is the energy.

They're related by a simple formula: Watts = Volts x Amps, usually written W = VI. A 230V 13A socket can deliver 230 x 13 Watts, or 2990W, usually written as 2.99kW where a kiloWatt is a thousand Watts.

As an example, the Paragon SC-2 1745W kiln uses less power than a 2kW convector heater. So, you can plug it into a regular socket. It costs about 14p/hour to run, whilst heating up at the fastest rate, but less normally as the relay cuts in and out.


It's interesting that a 10W radio will fill the room, a 100W light bulb will light the room, but a 1000W fan heater will barely warm the room. So, as we pay for electricity by the kilowatt, it's heating devices that cost the most to run. Which is why you get a big bill if you leave the immersion heater on.
Sadly, riding an excercise bike can only generate about 70W of light so, although the exercise keeps you warm, it's hard to be energy-independent. Especially as most of the light bulb's energy is heat rather than light.


Most domestic and small-business buildings have a main fusebox, or consumer unit. Different fuses restrict the amount of current that can be drawn by function groups, such as the lights on one floor, the power sockets on one floor, the kitchen sockets, ovens and grills, a shower and pump, or a garage and outside lights. If you exceed a fuse's rating, it pops.

To supply lights, the fusebox uses several ring mains, each ring separately fused and rated at 5A or about 1200W. Typically, a ring main starts at the fusebox, visits several wall switches and lights in different rooms on the same floor, and returns to the fusebox. The whole circuit is earthed at the fusebox. A lighting circuit is not designed to power heating devices.

To supply power sockets, the fusebox uses several ring mains, each ring separately fused and rated at 30A or about 7000W. Typically, a ring main starts at the fusebox, visits several double sockets in different rooms on the same floor, and returns to the fusebox. The whole circuit is earthed at the fusebox. A double socket accepts two 13A plugs.

To generalise, you can't plug lots of heating devices into all the sockets: neither the fuse nor the cable will survive, although the fuse should pop before the cable burns out. Although fuses are easy to reset or cheap to replace, replacing burnt-out wiring is difficult and expensive.

In older properties, several owners with varying levels of skill, may have changed the circuit or extended it. It's quite common for a ring main, to have a spur to another socket or even to another room. So, take care.


For accessories, options, and tools, such as mains-testing screwdrivers and multimeters, use the shop link below the menu bar near the top-right of every page.

THE POWER SUPPLY
UK 3-PIN 13A Plug

The Power Supply.

The smaller kilns have a 13A UK three-pin plug: so they're ready to go. The larger kilns need to be wired in: they don't use a plug.

As you can see in the diagram, the live, the brown wire, connects to a 13A fuse. The neutral, the blue wire, connects to the neutral pin. And the earth, a green-yellow wire, connects to the earth pin.

In the event of an electrical fault. there are six levels of protection. A small fuse, part of the kiln, protects the programmer. The 13A plug fuse protects the equipment. The metal casing is earthed. The fusebox fuse, typically 30A, protects the whole circuit. The fusebox usually has a separate earth-leak fuse. And the building has a fuse, typically 100A for a small house, to protect the whole electrical installation.

In addition, plugs have plastic insulation on the live and neutral pins so that you can't accidentally touch them whilst pushing the plug in or pulling it out, and the plug socket has an internal shield which only slides out of the way when the earth pin goes in.


The smaller kilns, up to 3120W, can use a regular mains socket. The 1095°C 3120W Xpress E-14A is the largest kiln, internally in volume, that can use a regular 230V mains socket. Above that, you'll need a dedicated power supply, 30A, 45A, 65A, or 75A, straight from the main fusebox.

SAFETY CUT-OFF SWITCHES

Cut-Off Switches.

US-made kilns often have live heating elements that are exposed whenever the door or lid is open. So, to comply with EU safety regulations, an additional switch, included in the price, is fitted to cut off the power whenever the kiln is opened. Exposed live elements are very dangerous, and illegal in the UK. So, there's no chance of turning on the kiln, putting some work in, and getting a shock. However, always take extra care.

The nature of safety switches is that they're not big 60A switches, but low current switches that turn off the main relay or relays. This technique is common in industrial equipment.

DELIVERY TOUCH DOWN
Delivery By Air

National And International Delivery.

Usually, the very popular SC series kilns are in stock, ready for delivery to your nominated address. All the larger kilns are made to order, take about 15 working days to build, about four working days to ship, and will arrive in a box, in a crate, or on a palette.

Paragon in the US makes around 400 different models, many of which are available in five colours or have modifications, so doesn't have a warehouse full of ready-to-ship kilns. Although Cherry Heaven is an EU distributor and service centre, it's not feasible to showcase the extensive range, especially as most kilns are protectively boxed, crated, or paletted for international shipping or local delivery.

Kilns regularly leave the US factory for the UK using reserved air cargo to minimise the freight charges. Air cargo typically takes four days. Sea freight takes at least seven weeks: or longer, as resellers often secure advance payments then wait to collect enough orders to fill a container.


If you call first, you can collect one of the smaller kilns from our warehouse: Cherry Heaven in West Holme village. However, a larger kiln, such as a crated Fusion 10, weighs 106kg and is 1300mm across, so it won't fit in a regular car.


Your kiln will usually be delivered by one of the well-known shipping companies, such as Chase Freight, City Link, Concordia, DHL, Fedex, Parcel Force, TNT, or UPS. When you sign for it, write unexamined by your signature. If there's any damage, take photos, don't touch the packing, and call the shipping company.

TEMPERATURE
Temperature

Temperature.

A kiln's maximum operating temperature sets limits on the materials and processes you can use. 1290°C is the highest temperature that standard kilns reach: above that, the materials and construction have to change, and the cost increases dramatically.

Porcelain and stoneware need about 1290°C, jewellery and low-fire ceramics about 1095°C, glass casting, fusing, sagging, and slumping about 925°C, and annealing about 650°C.

The maximum temperature is not related to the wattage: so a 4800W kiln does not get twice as hot as a 2400W kiln. The temperature depends on the elements, the firing chamber volume, and the programmer.

As with any device you buy, a kiln is not designed to be run full-on all the time. So, if you need to fire at 925°C for a long time, buy a 1095°C kiln, not a 925°C kiln. To give you a feel for temperature, here are the melting points for a few common materials:


MATERIAL °C
aluminium 659
copper 1083
glass 1700
gold 1063
lead 163
nickel 1452
platinum 1772
silver 962
steel 1371
tungsten 3399

I sometimes get asked if there's a platinum clay: there is, but it's an industrial product. Platinum melts at 1772°C, so a platimum clay would probably need to fire at around 1600°C: beyond the maximum temperature of conventional kilns.

CENTIGRADE AND FAHRENHEIT

The three main temperature scales are Celsius, Fahrenheit, and Kelvin. The metric system, used in the EU and most other countries, uses the Celsius scale. The everyday descriptions are:

In the Celsius temperature scale, pure water freezes at 0°C and boils at 100°C. Celsius is the international standard, having replaced the equivalent Centigrade in 1948.

In the Fahrenheit temperature scale, it freezes at 32°F and boils at 212°F. Fahrenheit is commonly used in the US, and sometimes conversationally in the UK.

In the Kelvin temperature scale, it freezes at 273.15K and boils at 373.15K. Kelvin is not measured in degrees Kelvin, just Kelvin: so it's written K, not °K.

In the Kelvin scale, absolute zero is the hypothetical, but unattainable, temperature at which matter exhibits zero entropy. It's defined as being precisely 0K or -273.15°C. Celsius and Kelvin are used in scientific work.

To convert Celsius to Fahreneit, multiply by 9, divide by 5, and add 32. To convert Fahrenheit to Celsius, subtract 32, divide by 9, and multiply by 5.

KILN FURNITURE: A GENERAL INTRODUCTION IMPORTANT
A Paragon Kiln Shelf Kit

Kiln Furniture: Shelves And Posts.

Most kilns have a recommended furniture kit. Delivery companies have a low rate for parcels less than 30kg so, for smaller kilns weighing less than 30Kg, the kit is generally one shelf and four posts: included in the price because it fits in the box and doesn't add much to the shipping weight.

You get a professional, durable, cordierite shelf with four 12mm high posts. You don't get a soft, ceramic-fibre shelf, often described as free, that will gradually break up and need replacing.

Shelf kits usually include 25mm x 25mm x 12mm shelf posts, When flat, they're 12mm high: on their sides, they're 25mm. Other sizes, up to 150mm high, are available, so you can choose the shelf spacing that suits your kiln and your work.

The recommended kit is usually the simplest that works: not an expensive collection that I've put together for you. However, extra shelf kits allow you to stack your work, optimising your use of the firing chamber volume, the unit-cost of firing, and your time. And extra half-shelves or smaller shelves allow you to fire a mix of shorter and taller pieces.


For larger kilns weighing more than 30Kg, shelf kits are not included in the price because you'll probably want to choose your own mix of shelves, half-shelves, smaller shelves, and assorted-height posts.


One shelf should stay on the floor of the firing chamber all the time in case you accidentally spill or melt anything: solidified glass or metal is impossible to pick off without damaging the ceramic-fibre or firebrick.

Shelves are not meant to be an exact fit in the kiln. You need finger space all round and they mustn't scrape the kiln walls every time they're put in or taken out. Be careful lifting heavy shelves out of a top-opening kiln: if you drop them they will damage the firebricks.

Although they look tough, most ceramics break if they're dropped on a hard floor, so it's a good idea to have spare shelves, especially if your business depends on your kiln or you're running courses.


During firing sequences with heating, holding, and cooling segments, the elements turn on and off repeatedly. In a small kiln, with little residual heat, the inevitable temperature changes can make glass crack as it expands and contracts. A thick heavy shelf stores heat and, because it's resting on posts, the air circulates, helping to even out the normal temperature fluctuations.


If you're buying your first kiln, you're probably interested in one material, such as silver clay, or one process, such as enamelling. However, after a few successes, and failures, most people want to try different materials, make larger pieces, experiment with combinations, fire more at a time, and soon become interested in something else: or everything else. Some start a business or run classes.

You might want a full shelf, two half-shelves, several mixed shelves, a set of shelf posts, a bead-mandrel holder, glass separator, hot gloves, kiln wash, a knife-making rack, pyrometric cones, a tile holder, or other accessories.

Shelves are heavy, so kits ordered separately need a box and protective packing and attract an extra delivery charge. Outside the UK mainland, this might be expensive. So, if you think you'll need them, order them with your kiln, along with any other accessories, materials, parts, or tools.


For dichroics, enamelling, and glass fusing, put kiln paper on the shelf to stop the glass sticking: it's simpler and cleaner to use than glass separator. Bullseye Thinfire shelf paper, probably the most popular, ensures easy separation between your glass and the kiln shelf. One side feels slightly smoother than the other: that's the glass side.

Generally, glasswork needs radiant heat and will fuse, sag, or slump better on one shelf than between closely stacked shelves, although experienced glass artists often use several shelves succesfully.

Delicate pieces can be fired on a puffed-up ceramic-fibre cloth: on a shelf. Round pieces, that could roll to one side, can be fired on a hollowed-out ceramic-fibre block. However, if the kin has elements in the bottom as with the Mini-Kiln and Prometheus Pro-7, a cloth or block will act as insulator and the kiln might overheat.

Particulates represent a health risk if they're breathed in, so wear a HEPA mask when cleaning out your kiln, mixing kiln wash, and working with ceramic-fibre blocks, ceramic cloths, and papers. And, ideally, use protective glasses.

If you want to touch anything hot, or move your kiln before it's cooled off, it's important to wear heat-resistant gloves. And, if you want to look into a red-hot kiln, even briefly, wear glare-resistant glasses to protect your eyes from IR and UV.


If your day-to-day work depends on your kiln and down-time will be disruptive or expensive, it's a good idea to have spares: extra shelves, a selection of posts, elements, a relay, and a thermocouple.

You can learn about ceramic blocks and cloths, charcoal, dust masks, glare-resistant glasses, glass separator, heat-resistant gloves, kiln vents, kiln wash, programmers, protective glasses, USB interfaces, shelf paper, tools, and other accessories, using the accessories link below the menu bar near the top of the front page. And they're all in the on-line shop.


Shelves are checked before despatch and are wrapped protectively. But they're not guaranteed and we cannot be responsible for any later damage.

Normally, pieces are put into the kiln on a shelf. When they've been fired, the shelf is taken out and put on ceramic fibre blocks, in a tray of vermiculite, or on some other heat-resistant surface, to cool. A kitchen tile is not thick enough: the heat will go through and might burn the work surface.

USING KILN FURNITURE

Kinl Furniture.

Never fire anything on the exposed floor of the firing chamber. If moulten metal, glass, or enamel sticks to the ceramic fibre or firebrick, it will be very difficult to remove without causing damage, particularly as glaze or enamelling drips can be asbsorbed into the ceramic fibre and then ruin the element. Shelves, and shelf paper, are designed to prevent this happening.

Cordierite is brittle so, if you drop the shelf, it will usually break. Although shelves can be repaired, it's not worth the risk as, if they break again, it will be just as you put your delicate unfired pieces in the kiln. It's a good idea to have spare shelves, especially if your business depends on your kiln.
Shelf posts are made of the same material. Some people use three, as there's no chance of the shelf rocking: although four minimises the risk of the shelf tipping if you put a heavy piece off-centre.

If you've washed a shelf, or it's got wet, you'll need to dry it before firing, or the water will turn to steam and the pressure increase may crack or shatter the shelf. It's unlikely, but it could explode, so wear safety glasses.

Although shelves last a long time, the continual expansion and contraction will cause surface cracks: this is normal. Providing a shelf doesn't look as though it will break, you can carry on using it.


Most furniture kits include 25mm x 25mm x 12mm posts. They can be used flat to lift the shelf 12mm, or on their edges to lift the shelf 25mm. When you use four on their edges, put two north-south and two east-west so that the shelf doesn't wobble over.


If you break a shelf, you may still be able to use the pieces, on posts, for smaller work. If you buy a tile-cutting saw, you can make a regular-shaped shelf from an irregular piece.


For accessories, options, and tools, such as kiln shelves and posts, use the shop link below the menu bar near the top-right of every page.

CERAMIC FIBRE CLOTHS
Ceramic Fibre Cloths

Ceramic Cloths.

Fibre cloths are used to support delicate pieces in the kiln, either as a flat surface or cut into pieces. The cloths in the on-line shop are 225mm x 150mm x 6mm.


For accessories, options, and tools, such as ceramic fibre coths, use the shop link below the menu bar near the top-right of every page.

CERAMIC FIBRE BLOCKS
Ceramic Fibre Blocks

Ceramic Blocks.

If you've just dried or fired Art Clay or PMC, you need to take out the hot shelf and put it somewhere safe. Ceramic fibre blocks are ideal.

Be careful if you use any other materials: plastic will melt, wood will burn, glass will shatter, a tile will crack, a firebrick is brittle and heavy, and welders' squares and plumbers' mats are too thin. On a kitchen worktop, the wood will burn or the laminate will discolour and lift. Metal will just conduct the heat to the surface it's resting on.

If you're firing anything small and rounded, be careful that it doesn't roll off and break or burn something. The ceramic fibre block is very soft, so you could make a slight hollow on one side. However, if you fire two things, make sure they don't roll together and touch.

The heat-resistant block in the on-line shop is made from light ceramic fibre. It's 150mm x 100mm x 50mm. Unlike a heavy rough-cast fire brick, won't scratch the work top if you move it about.


For accessories, options, and tools, such as ceramic blocks, use the shop link below the menu bar near the top-right of every page.

VERMICULITE
Vermiculite

Vermiculite.

Vermiculite is used to support delicate work in your kiln or, spread in a tray, to act as a soft heat-resistant surface when you take things out of the kiln. It'll last a long time, although it will eventually break up.

The vermiculite in the photo is expanded hydrated phlogopite mica: the particles are very light, non-toxic, and won't fuse until at least 1200°C, about 2200°F.

If you use a tray of vermiculite, keep it covered when it's not in use, to prevent stray materials mixing and getting stuck to your work. Also, vermiculite particles are very light and can jump onto your clothes if your movement generates static electricity, or blow everywhere if there's a window open.


It's not easy to find vermiculite in the high street. If you do, it might have plant food or polystyrene particles mixed in: so be careful.

The Kitiki vermiculite comes in a white plastic screw-top pot for convenience and safety: not a plastic bag, and not a pot that can't be closed properly once the seal has been broken.

Although it's filled to the brim during packing, particles settle and it may not look quite full when you open it. It's plainly much easier to fill a pot with a fixed volume than to measure out a fixed weight every time.


For accessories, options, and tools, such as vermiculite, use the shop link below the menu bar near the top-right of every page.

KILN PAPER
Ceramic Fibre Paper

Kiln Paper.

Kiln paper, often called shelf paper, consists of compressed ceramic fibres held together with a binder. It looks like normal thick paper, and can be cut to size easily with scissors. As with any fibrous material, don't get the fibres on your hands or breathe them in.

During firing, the room should be vented as the burning binder may smell and release a little smoke. Usually, the paper burns away, leaving a little dust: so clean out the kiln regularly.

The paper in the on-line shop comes as single sheets, each one 520mm x 520mm square, or as a pack of four. Although kiln paper is much simpler, cleaner, and quicker to use than kiln wash, it does cost more. And it doesn't protect the shelf against ceramic glazes which would just soak through.


For accessories, options, and tools, such as kiln paper, use the shop link below the menu bar near the top-right of every page.

GLASS SEPARATOR

Kiln Wash.

If a glaze or hot glass sticks to the kiln shelf, it's very difficult to remove without pulling away part of the shelf surface. To protect the shelf and make separation easy, you need to brush on a coat of glass separator or use a protective layer of kiln paper.

Glass separator, often called kiln wash, consists of finely ground minerals that don't fuse at normal firing temperatures. It prevents glass and glazes sticking to the shelf. It's mixed with water and painted on using a soft-bristle haik brush. Usually, several thin coats are applied in different directions.

A few tips: don't use glass separator on ceramic fibre; don't get the powder on your hands or breathe it in; stir the mixture every time you dip the brush in; and store it in a glass jar.

You need to dry the shelf before firing, or the water will turn to steam and the sudden pressure increase may crack or shatter the shelf. It's unlikely, but it could explode, so always wear safety glasses when you open your kiln.

You can let it dry naturally in a warm place overnight, put it on a central heating radiator, or stand it on kiln posts and heat it, with the kiln vent open, at 150°C for 30 minutes.


Generally, glass separator will last for several firings: the lower the temperature, the longer it lasts. However, most users re-coat before firing. Before applying another layer, smooth the shelf surface with some wet+dry paper. For most small pieces, kiln paper is easier to use.

Kiln wash should never be applied to the lid, door, or walls of the kiln, and it's especially important to keep it away from the elements.

PROGRAMMERS  0:0:0
Orton Sentry Xpress

Programmers.

Most modern kilns use an electronic programmer, or digital controller, such as the Orton Sentry. A programmer allows you to set up accurate drying, heating, holding, and cooling sequences: and do something else whilst the sequence is running. The programmers are easy to use, and the sequences can be saved for the future.

Paragon kilns don't have programmers with pre-set sequences: you can choose the sequence temperatures, times, and heating and cooling rates.
As a beginner, pre-sets may seem to be an advantage. However, having experimented, many people fire materials, or combinations of materials, at different temperatures and for different times than are recommended.
And, later, you might want to work with other processes and materials such as: china painting, dichroic glass, dolls, enamels, fusing, glass-bead annealing, glazes, gold paints, low-fire ceramics, sagging, and slumping.

The programmer is partly controlled by a temperature-sensing thermocouple. However, kilns on full heat will overshoot the set temperature briefly before settling back. Using the kiln for low-temperature processes, such as baking Fimo Polymer Clay, needs care.
The effects of this overshoot can largely be prevented by setting a lower temperature or a lower heating rate. Usually, this has no effect on your work, but keeping a kiln log will help you learn how to set temperatures.


Paragon kilns usually use the 3-key Sentry Xpress 4.0 or the 12-key Sentry 2.0 digital programmer, both developed by Paragon and the Orton Ceramic Foundation. To learn more about programmers, use the main-menu link below the menu bar, then choose programmers.

A programmer, or digital controller, allows you to set up, and re-use, accurate drying, heating, holding, and cooling sequences: and do something else whilst the sequence is running. A sequence can consist of up to eight segments.
A segment is one step in a sequence: often the time it takes to reach a target temperature. For example: one segment could take 50 minutes to reach 650°C; another could hold at 850°C for 12 minutes; and another could take 90 minutes to cool down.

Paragon kilns don't have programmers with pre-set sequences: you can choose the sequence temperatures, times, and heating and cooling rates.
As a beginner, pre-sets may seem to be an advantage. However, having experimented, many people fire materials, or combinations of materials, at different temperatures and for different times than are recommended.
And, later, you might want to work with other processes and materials such as: china painting, dichroic glass, dolls, enamels, fusing, glass-bead annealing, glazes, gold paints, low-fire ceramics, sagging, and slumping.


The programmer is partly controlled by a temperature-sensing thermocouple. However, kilns on full heat will overshoot the set temperature briefly before settling back. Using the kiln for low-temperature processes, such as baking Fimo Polymer Clay, needs care.
The effects of this overshoot can largely be prevented by setting a lower temperature or a lower heating rate. Usually, this has no effect on your work, but keeping a kiln log, described below, will help you learn how to set temperatures.


Most programmers have a temperature alarm that you can set. Here are a few reasons why the alarm will sound, or why you will want to use it:

Drift the temperature was set to lower than room temperature
Drift if you've propped the lid open, use the alarm as a reminder
Drift if you've set a temperature, use the alarm as a reminder
Drift if you need to look through the window, use the alarm as a reminder
Drift if you want to turn the kiln off manually, use the alarm as a reminder

To turn off the alarm, press any key except STOP. All the functions of the alarm will be described in the appropriate programmer's manual.


The kiln's maximum cooling rate, even with the lid or door open, depends on the type of kiln. If it takes four hours to cool from 650°C to 100°C the programmer can't speed this up, even if you program a full cooling rate. The purpose of controlled cooling is to make the kiln cool down slower than it would if you turned it off and allowed it to cool on its own.

KILN TIMER
Digital Timer

Using A Digital Timer.

Although most kilns come with programmers, it's very easy to walk off and forget. A digital kiln-timer, is something you take with you to remind you that time's up.

It's particularly useful when using the Kitiki Mini-Kiln which, although it has a programmable maximum temperature, doesn't turn itself off. The Kitiki Timer, in the on-line shop, can be set to beep at any time up to 100 minutes: just set the minutes and seconds, and start the timer. It measures 86mm x 47mm x 16mm.

KEEP A KILN LOG

Kiln Log.

The best way to learn about your kiln is to keep a firing log, listing the material you used, the shelves and their spacing, the firing cycle, and the end result. The log is vital if you're experimenting with dichroic glasses, enamels, glazes, and other colour-dependent materials.

Also, if you're firing the kiln for the first time for several months, you can review your logbook to regain a quick feel for what to try.

FIRST USE

First Firing.

Most heating devices smell when used for the first few times, so use the kiln in a well-ventilated room. The stainless steel casing, or the paint, may eventually discolour, particularly around the door.

As the ceramic chamber expands and contracts in use, small cracks may appear. These are normal and harmless, and will not affect the firing.

Relays used with digital programmers click as the elements are turned on and off to control the heating or cooling rate, or keep a steady temperature. If you're working with other people, tell them that the clicking is normal: otherwise they might think it's a fault and turn the kiln off.

Elements can be destroyed by contact with silica and silica compounds, and by reduction firing: so read the notes that come with your kiln.

Inside the firing chamber, a heat-sensitive thermocouple, connected to the programmer, projects into the firing space. If you accidently push it back, it can't give accurate readings and the kiln will overheat. Although the programmer provides error messages to report problems, it won't warn you about this.

Firing Art Clay can leave very faint traces of silver in the pores of the ceramic firing chamber. This may affect the colour of some glasses, so always do a colour test first.

If you're stacking several shelves or firing pieces that nearly fill the firing chamber, make sure that there's 25mm clear space around the thermocouple, or it won't be able to read the temperature acurately.

TEMPERATURE STABILITY

Temperature Stability.

Small ceramic-fibre kilns, such as those in the SC series, heat very quickly. Although the thermocouple checks the interior temperature every four or five seconds, the walls of the kiln containing the elements will be hotter and will still radiate heat for a short while after the element is turned off. Also, the programmer averages out the changes rather than trying to turn the elements on or off every few seconds.

On the fastest heating rate, with the elements on the whole time, the temperature will overshoot the set temperature, possibly by as much as 6-7%. If this adversely affects your work, set a slower heating rate.

OPENING THE DOOR OR LID DURING FIRING

Firing.

Generally, opening the door or lid of a hot kiln won't damage the firebricks. However, most manufacturers recommend that you wait until you can unload pieces bare-handed before opening the lid of the kiln to prevent damage to your work, rather than to the kiln. For example, if you remove glass too soon, it may crack as it cools.

Most electric kilns are 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 changes without cracking.

You can open a hot kiln to remove raku pieces, open the lid to rake or emboss the surface of softened glass, or open ceramic fibre kilns, such as the SC-2, at 900°C, to remove silver clay.

Rapid firing won't harm your kiln, either. The K-23 bricks and ceramic fibre are less susceptible to cracking from rapid firing than any clay you will ever place inside the kiln.

KEEPING THE KILN CLEAN

Cleaning The Kiln.

One reader sent in this: the kilns were near the clean-up area, where the worker fettled off the mould marks and sanded down large greenware pieces. He'd then blow off the dust with a compressed air gun, all the time unmasked.

Clay contains silica. Dry clay contains free silica. Silica in the lungs causes silicosis. Silicosis causes illness and premature death. Always work in a well-ventilated area and wear a HEPA dust mask. Always clean up your work area regularly.


With top-opening glass kilns, tiny particles can sometimes drop onto the glass. Vacuum the kiln regularly. Alternatively, if it's a ceramic fibre lid, brush a coat of rigidiser onto the fibre.

The fibre absorbs the rigidizer much like a sponge, so you will need to dab it on rather than brush it. It only needs only one application. The ceramic fibre surface should be dry to the touch before firing the kiln but, the first time you fire after applying rigidizer, hold the kiln at 120°C for 20 minutes.

THERMOCOUPLES

Thermocouples.

Kilns measure the firing chamber temperature using a thermocouple: a metal or ceramic-sheathed rod that extends a short way into the firing chamber, usually from the back.

Some thermocouples do drift with age. Since they're not expensive, it's a good idea to order a spare when you buy the kiln. If there is a failure, you'll only have a few hours down-time, rather than a few days.

When thermocouples fail, the temperature display often becomes erratic or very inaccurate. Occasionally, problems can be caused by a loose thermocouple connection or a bare spot on the thermocouple wire touching the kiln case.

Uniquely, our SC-2 kiln has a sheathed thermocouple which prevents the possible corrosion, and eventual failure, of the bi-metallic tip: ocassionally caused by pollutants produced whilst heating some types of glass.


For accessories, options, and tools, such as K-Type and S-TYpe thermocouples, use the shop link below the menu bar near the top-right of every page.

REPAIRING HEATING ELEMENTS

Repairing Elements.

The short answer is don't. However, some users have repaired burned-out elements by twisting the broken ends together with pliers and heating the two ends to red heat with a small gas torch.

This rarely works for long because the element develops a protective oxide coating after many firings. The coating not only protects the wire from further oxidation, but it's also a good electrical insulator, so the connection made by twisting is electrically poor. The poor connection will not conduct current very well, locally over-heat during firing, and probably burn out again.

On very rare occasions if you're lucky, the wire gets just hot enough during firing to weld itself together without melting, making a good connection. However, usually, the twisted joint burns out near the end of the firing when the kiln is at its hottest: so the user gets just one more firing out of the element.


In the unlikely event of an element failing, elements laying in firebricks are inexpensive and easy to replace. Elements embedded in ceramic fibre can't be replaced: you'll need to replace the ceramic-fibre liner. In the case of an SC2, this is about 40% of the cost of a new kiln.


For accessories, options, and tools, such as relays and elements, use the shop link below the menu bar near the top-right of every page.

FIRING CHARACTERISTICS

How Electric Kilns Work.

Generally, as soon as a programmable kiln starts its firing sequence, it begins to heat up at a rate set by the programmer. It can't heat up quicker than it would do with the elements full on.

The thermocouple tells the programmer the current internal temperature and, depending on the sequence you've chosen, the programmer turns the elements on or off to control the sequence segments: the heating rate, the target temperature, the hold time, and the cooling rate. It can't cool down quicker than it would do with the kiln turned off. When the sequence is complete, the kiln beeps, and the sequence stops.


For safety, the programmer doesn't switch the full mains voltage. Instead it drives a relay, an electro-mechanical switch. The programmer uses a low voltage to activate the switch which turns the high voltage elements on or off.


When the target temperature is reached, the programmer switches the elements off. However, residual heat in the firing chamber allows the internal temperature to overshoot the target temperature briefly before starting to fall back.

This overshoot is more evident at low temperatures than at high temperatures, and in small kilns rather than large kilns. For example: 300°C will probably overshoot to 330°C whereas 800°C will probably only overshoot to 805°C before starting to fall back.

During the hold-time, with the elements still off, the temperature starts to fall. When the programmer switches the elements back on, the firing chamber will initially absorb some of the new heat before the temperature recovers. The continual switching of the elements on and off causes the internal temperature to oscillate either side of the target temperature.

This is similar to central heating. If you set it for 21°C, it probably oscillates, quite slowly, around 20°C to 22°C: and you won't notice. The accuracy will depend on where the thermostat is sited, how quickly it responds, how accurate it is, how long it takes for the radiators to heat up, and if you have doors and windows open. The temperature will probably be slightly different in each room.

So, regardless of the thermocouple temperature, the actual temperature of your work will be slightly different, depending on its position on the kiln shelf, the vertical spacing of any stacked shelves, and its nearness to the elements, a lid, a door, a bead door, or a window. Learn to take it into account if you're working with temperature-critical materials or processes.


Remember that glass needs radiant heat and will fuse, sag, or slump better on one shelf at the bottom than between closely stacked shelves.


Kiln doors and lids are not meant to be a perfect fit otherwise, at high temperatures, there'd be no room for expansion and movement, and the door could stick and the ceramic-fibre or firebricks could crack.

All kilns smell a bit, and even produce whisps of smoke, during the first firings, just like a toaster or a fan heater. If you're worried about fumes, open a window.

Eventually, with normal use, kilns discolour slightly, inside and outside, and some firebricks might develop hairline cracks. Your kiln is a versatile, robust, red-hot tool: not an ornament.

KEEPING A KILN LOG

Keeping A Kiln Log.

Using your kiln successfully needs critical research and frequent tests, especially as things that work for your friends and teachers might not work in the same way for you. It's also very important to learn how to creatively use unexpected effects. So, keep a firing log:


Buy a durable notebook. Use a new page for every firing, and draw diagrams of the shelves, their vertical spacing, and the position of your work on the shelves. Along with your work, put a few scraps at different places on the shelves to learn how things change. Describe the material, the shape of your work, the firing cycle, and the end result. Add a few photos and sketches, and mark the page corners with coloured dots or symbols as a quick reminder of your success rating.

A kiln log is vital if you're experimenting with temperature-sensitive materials or working with coloured dichroic glasses, enamels, glazes, or china paints, and a skilled artist will use the kiln log to advantage to re-create effects. It'll be particularly useful if you have to repeat a commission, or you have a long holiday before returning to your studio.


Some Paragon kilns have a Sentry 12-key or a Sentinel Touch Screen programmer which can be connected to your computer through a factory-fitted USB interface. The Control Master software allows you to control and monitor the firing, and analyse, arrange, print out, and save the data. If you want this feature, make sure you order the USB interface in the on-line shop.

FIRING CERAMICS, PORCELAIN, POTTERY, AND STONEWARE

Firing Ceramics.

Before it's fired, greenware, or unfired clay, needs to be dried to evaporate the water: just like Art Clay and PMC. If you don't dry it completely, the water will turn to steam during firing and the pressure increase might crack or shatter the clay. It's unlikely, but it could explode, so wear safety glasses when you open the kiln.

The most expensive way to dry ware is to heat it in a kiln. The moisture in the clay rusts the kiln, wears out elements faster, and wastes electricity.

After firing ceramics, leave your work in the kiln to cool naturally. If you take it out too soon, it may crack from thermal shock. Never fire tempered glass as it could explode.

When you fire your pieces, use some of the empty shelf space to fire small test materials and shapes. It's a good way to learn.

PYROMETRIC CONES

Pyrometric Cones.

If you work with Art Clay, PMC, or glass, you'll understand how the ramp-hold Orton Sentry programmer works. However, if you want to work with ceramics, you may prefer to use pyrometric cones.

Pyrometric cones are slender pyramids, made from about 100 carefully controlled compositions, that measure the effect of time and temperature. As the cone nears its maturing range, it softens and the tip begins to bend down under it's own weight. Ceramics are usually sold with firing instructions, which include the cone number.

Cone-Fire, generally used for ceramics, pottery, stoneware, glazes, china painting, and decals, fires to a set pyrometric cone number listed in the Orton cone tables. It's not designed for Art Clay, enameling, glass work, or heat treating.
Cone-Fire will only be successful if you understand how cones and cone numbers work. Unlike a programmer, a cone is a visual indicator that your work has been fired for the correct combination of kiln temperature, kiln atmosphere, and time.


If you bought a ceramics kiln with a cone-fire programmer, you can fire using cones because the programmer is set up to use cone numbers. If you have a ramp-hold programmer, you'll need to be able to convert cone numbers to temperature and time. Of course, you can't use a cone that matures at a higher temperature than your kiln can maintain.

Cone numbers were originally set from 1 to 10, 1 being the coolest. However, cooler cones were introduced from 022 to 01. To fire faster or slower than the segments listed, change the rates by 10 - 20%. However, the last segment should always be 108.

WORKING WITH GLAZES

Glazes.

At high temperatures, glazes will stick to anything. Always put your work on a protective shelf, not on the exposed firing chamber floor.

Some glazes may release toxic chemicals into food or drink. Make sure that you use an approved and tested product, applied and fired as recommended.

FIREBRICKS
Firebricks

Firebricks.

Kiln firebricks, unlike home-hearth firebricks, are not as hard as they look and can sometimes shed fine dust in the fiuring chamber. It's important to vacuum out any dust. However, be very careful with the vacuum cleaner brush-cup.

Kiln doors and lids are not meant to be a perfect fit otherwise, at high temperatures, there'd be no room for expansion and the door could stick and the ceramic-fibre or firebricks could crack. So, a thin line of light around parts of the door or lid is normal.

The bottom of the kiln needs a coat of kiln wash: one that's rated to 1290°C. Don't get any kiln wash on the elements or the sides of the kiln.

Eventually, with normal use, kilns discolour slightly, inside and outside, and some firebricks might develop hairline cracks, although they'll close up at high temperatures. Remember, your kiln is a robust, versatile, red-hot tool: not an ornament.

It won't do any harm to the firebricks to open the door slightly for a few seconds to check work in progress. If you look at hot materials in a kiln regularly, either through a peephole or by opening the lid or door, wear tinted glasses. You can buy hot glasses in the on-line shop.


For accessories, options, and tools, such as kiln wash and hot glasses, use the shop link below the menu bar near the top-right of every page.

SECOND-HAND KILNS

It's worth adding that, to help prevent you becoming legal prey, buying a second-hand kiln has risks: you don't know if the elements have been over-fired and might soon fail, the programmer may have an intermittent fault, the relays may be sticky, the thermocouple might not be accurate, it could have been poorly repaired, you'll have no guarantee, and, if it does fail quickly, the seller won't take it back.


Art Clay UK Cherry Heaven Electric Kilns Electric Tumblers Euroversity Kitiki Learning English Lucas Cameron Mini Kiln Oxford English Oxford English Training Paragon Kilns International Paragon Kilns UK Paragon Kilns DE Paragon Kilns EU Professor English Prometheus Kilns