Over the years, we've been sent lots of tips and ideas. If you have any suggestions that would help other kiln users, please email, and attach a photo if appropriate. Use the mail link below the menu bar.

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

Help with choosing a kiln, safety practices and equipment, and service and repair issues, are on other pages. Use the start link below the menu bar, then choose the appropriate page.

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 metal 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.

It's not easy to buy specialist safety equipment in the high street, so there's a selection in the on-line shop. Use the shop link below the menu bar. Alternatively, visit the Cherry Heaven shop in Corfe Castle village.

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 and, if you have two kilns, at least 1000mm apart. Never put insulation around a kiln to try to conserve energy: the wiring and the programmer will overheat, and may burn out.

If your kiln comes with a stand, don't abandon it and put the kiln on firebricks 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.

Kilns such as the SC-2 and SC-3 can use a regular mains socket, and keep cool enough to stand on a normal worktop. Kilns such as the Xpress E-14A need to be on a heat-resistant surface. Kilns like the Janus 27 need a dedicated circuit, and should stand on the floor: a heat-resistant floor not a wooden floor.

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. Opening the door mid-sequence will cause a sudden drop in temperature: glass pieces may crack.

Although kilns have 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. Ventilate the area.

A DOMESTIC FUSEBOX

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, and a 1000W fan heater will 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 60W 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.

DRESSING UP THE KILN

Nearly every kiln has a recommended furniture kit, an appropriate mix of shelves and shelf posts, included in the price. Extra shelf kits allow you to add a layer at a time, optimising your use of the firing chamber volume, and your time.

Usually, the included kit is more comprehensive than an extra kit. For example, the included kit for a large kiln could consist of two full shelves, two half shelves, a good assortment of posts, and a bag of glass separator, whereas an extra kit could consist of one full shelf, one half shelf, and enough posts for the two shelves.

Shelves and posts are made of cordierite, a magnesium aluminium silicate that resists thermal distortion and fracture. A thick shelf, on posts, heats and cools evenly: particularly important for glass work. Kiln shelf paper is simpler and more convenient to use than glass separator for stopping enamels and glass sticking to the shelf.

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.

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.

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.

PROTECTION

Vermiculite is used to support delicate pieces in the kiln or, spread in a tray, gives you somewhere to put the hot kiln shelf whilst it cools.

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.

It's not easy to find vermiculite in the high street. The vermiculite in the on-line shop comes in 200gm or 400gm bags and will last a long time.

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.

A COMFORT ZONE

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.

KEEP IT COOL

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.

CERAMIC FIBRE 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.

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.

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 these programmers, use the start 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:

the temperature was set to lower than room temperature
if you've propped the lid open, use the alarm as a reminder
if you've set a temperature, use the alarm as a reminder
if you need to look through the window, use the alarm as a reminder
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.

JUST A MINUTE

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.

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.

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.

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.

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.

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 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.

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.

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 the SC series, this is about a quarter of the cost of the kiln.

All programmable kilns work in the same way: the thermocouple checks the internal temperature regularly and tells the programmer to switch the elements on or off to control the heating or cooling rate.

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

This is more noticeable at low temperatures than at high temperatures. For example: 300°C will probably overshoot to 320°C whereas 800°C will probably only overshoot to 810°C before starting to fall back. Take this into account if you're working with temperature-critical materials or processes.

During the hold-time, with the elements still off, the internal temperature falls. Although the programmer will soon switch 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 cycle around the target temperature.

The actual temperature of your work will be affected, slightly, by 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, a window, or a peephole.

Remember that glass needs radiant heat and will fuse, sag, or slump better on one shelf than between 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 the door could stick and the ceramic-fibre or firebricks could crack.

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

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 may 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.

If you work with Art Clay, PMC, or glass, you'll understand how the ramp-hold Orton Sentry Xpress programmer works. However, if you want to work with ceramics, you may prefer to use pyrometric cones. To learn more about cone firing, return to the menus.

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. To learn more, use the start link below the menu bar, then choose programmers, then cone-fire.

At high temperatures, glazes will stick to anything. Always put your work on a protected 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.

If you're working at home, check your building and contents insurance to see what's covered if there's an accident. You might find that using a kiln is excluded. Your policy might not cover you if you're running a small 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.