The UltraLite Kiln an 845°C, 250W, on-off, compact, round kiln, with a lift-off lid. The UltraLite Kiln is the smallest kiln in the UK.

The UltraLite Kiln is suitable for small-scale work: drying and firing Art Clay and PMC silver clays, enamelling, glass fusing, gold leaf keum-boo work, and mixed-media jewellery.

The UK kiln is rated at 230V 250W, so can use a regular mains socket. It heats and cools quickly, but costs very little to run. It's small enough to use in your home, school, craft workshop, jewellery studio, or take to a course venue, as it only weighs about 1Kg.

The US-made kiln has been modified for UK voltage, it's CE marked, and the power cable has a regular UK plug. It comes with a 0.4m power cable, so you might need a short extension. If it's a multi-socket extension, each socket should have a switch so that, when you turn the kiln off, you don't turn other things off as well.

The ceramic-fibre body measures 127mm x 65mm externally, and is mounted on a 62mm high metal stand. There's a front cut-out for access, which also acts as a vent for any processes that release fumes.

The ceramic-fibre firing chamber measures 76mm x 38mm internally, and only heats from the bottom, with the fast-firing element safely embedded in a removable fibre disc. Putting the lid off-centre will effectively vent the kiln and reduce the temperature.

The recommended firing kit for the UltraLite, included in the price, consists of one 77mm x 4mm cordierite firing disc for Art Clay and PMC metal clays. Cordierite is a magnesium aluminium silicate that resists thermal distortion and fracture.

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 or you're running courses.

Kiln shelf paper will stop enamels and glass sticking to the firing disc. Kiln shelf paper is simpler and more convenient to use than glass separator for stopping enamels and glass sticking to the firing disc.

Because the kiln only heats from the bottom, you can't stack the discs and fire several layers of work at the same time. However, two extra discs allow you to put one on the lid to dry metal clays and use the other to lay out your next pieces ready for firing.

The two red-brass hot-lids, one of which has a shallow hollow for round pieces, are generally used for keum-boo work, and are described below.

The Ultra Lite Kiln is a good first-kiln, popular with keum-boo artists. Apart from its internal size, the only minor limitation is that, although 845°C is hot enough for silver metal-clays, it's not hot enough for gold metal-clays, ceramics, porcelain, pottery, and stoneware: they need a 1260°C or 1290°C kiln.

Although the elements are embedded in ceramic fibre, an important safety feature, never get careless: kilns are hot and connected to the mains.

Set up your UltraLite in a well-ventilated room, on a heat-resistant surface, at least 300mm away from any doors, walls, cupboards, or curtains.

If the room is protected by a fire-prevention sprinkler system, don’t position the kiln under a heat-sensitive sprinkler: it might come on, triggered by natural rising heat, and flood the room.

Don’t keep any volatile materials, such as paints, solvents, oils, or petrol, in the same room. Some vapours, or even clouds of very fine dust, can ignite easily and explode.

Some organic materials, such as Art Clay Cork Clay, burn during firing and traces of smoke will come out of the door vent and from around the door. Your kiln room needs to have ventilation.

Wherever you use your UltraLite, you’ll need somewhere to put hot shelves, such as on a ceramic fibre block or in a tray of vermiculite particles. Also, as the lid will be hot when you take it off, you'll need another tile to put the lid on.

Kilns made outside the UK have been re-engineered to work on a single-phase 230V-240V mains supply. They've been comprehensively tested to meet the demanding UL 499 standard in the US and CE standard in the EU.

UK voltage used to be 240V and European used to be 220V. The EU decided to harmonise the voltage to 230V, but the implementation costs were too high for almost no real benefit. So, to appear harmonised, the legal voltage limits were changed to 230V, but within the range 216V-253V. Generally, in the UK, 240V is a reliable average.

One accurate long-term test showed a cycle occurring daily between Monday and Friday. The voltage at night rose to around 242V. During office hours, the voltage dropped to about 235V, probably due to manufacturing, transport, and offices increasing the load on the National Grid. During the weekend, the voltage was generally around 240V and did not show the daily fluctuations.

The elements in ceramic-fibre kilns are safely embedded in the fibre. The elements in firebrick kilns are turned off by a legally-necessary lid or door safety switch. However, never get careless: kilns are very hot and connected to the mains.

Your UltraLite is rated at 230V 250W, so will draw just over 1A. Any kiln with a rating of less than 3000W can use a regular mains socket. However, circuits are not designed to power a kiln and lots of heating devices such as washing machines, dishwashers, kettles, and convector heaters.

It's quite common for light bulbs to pop just as you turn them on due to a higher-than-usual initial power surge. If your kiln is on a shared fuse, anything that pops the fuse will turn off your kiln. So, ideally, put your kiln on a separate pop-up fuse.

Don’t use a multi-way adaptor or an extension lead unless it’s absolutely necessary. Extension leads should never be used coiled or whilst on a drum as heat will build. Make sure that you don’t have loose cables where you walk.

As with all electrical equipment, don’t get the kiln wet and don’t touch it with wet hands. Although some kilns have a built-in safety cut out, all equipment in a work environment should plug into an electronic safety-trip adapter, sometimes called an RCD.

Always unplug the kiln when it’s not in use, you’re cleaning it, or it’s being serviced.

It'll be too late to think about safety practices and equipment after an accident. Apart from kiln accessories, the on-line shop includes heat resistant ceramic blocks and cloths, digital reminder-timers, fire extinguishers, heat-resistant gloves, and glare-resistant glasses.

It's important to have your fire extinguisher near your kiln. 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.

For private home use, check your building and contents insurance for relevant exclusions. For business use, you'll need public liability insurance and will have to comply with health and safety regulations.

Businesses and course providers might have to get change-of-use planning consent for proposed building changes and provide staff training, safety glasses, fire extinguishers, first-aid materials, disabled access, a bathroom, and fire exits.

Don’t let the temperature of your workshop exceed 40°C: keep a window open or use an extractor fan. Don’t leave your kiln unattended whilst firing.

Wear protective glasses when you look into a hot kiln, and wear thick work gloves when loading or unloading unless you know the kiln is at room temperature.

If you’re using a tool to lift out the shelf, make sure it’s wide enough to stop the shelf, and your work, falling off. Stainless steel BBQ fish turners are usually OK: teflon coated ones will burn.

Don’t let unsupervised children into your workshop or studio.

Never put insulation around a kiln to try to conserve energy: the programmer and the wiring will overheat, and may burn out.

Don’t fire any materials unless you know how they behave at high temperatures. Some may release poisonous fumes, explode, or corrode the thermocouple.

The paint will gradually discolour around the door, particularly if you open it whilst the inside is still hot.

Turn on the kiln and let it heat for 30 minutes with the cover off, and a further 15 minutes with the cover on. Generally, it will only need 45 minutes to reach the maximum temperature. A little faint smoke and a slight burning smell are normal.

Turn the kiln off, remove the lid, put a test piece of metal clay on the disk, put the lid back on, turn on the kiln, and fire it for about 30 minutes. It should go an orange-red.

THE CERAMIC INSERT

Place the ceramic disk in the kiln, textured side down, and pre-heat the kiln with the lid on for 35 minutes. Turn the kiln off, remove the lid, put a small test piece on the disk, turn on the kiln, and fire the metal clay for about 15 minutes to allow the binder to burn off. Then fire for another 15 minutes with the lid on.

Larger pieces will need firing on both sides, so turn your work over and repeat the firing. If you're using tweezers, wait until the work has cooled a bit. Before firing a second piece, put the lid on and let it heat for about 15 minutes.

You can try firing without the lid, with the lid off-centre, or with the lid on for some of the time: whatever works best. However, always check that the metal clay is still an orange-red. If the clay starts to shimmer, or show silver flashes or streaks, remove the lid as it's getting too hot.

As the maximum temperature should be about 845°C, there's little risk of over-firing your work as silver doesn't melt until 962°C.

Because the kiln heats from the bottom, you can't stack the discs. However, two extra discs allow you to put one on the lid to dry metal clays and use the other to lay out your next pieces for firing.

If your pieces are delicate or irregularly shaped, you could rest them on a thin ceramic-fibre cloth so they're supported during drying and firing. A thick cloth will act as an insulator.

Firing metal clay shaped around cork clay will inevitably produce flame, smoke, and a smell. As with fusing glass, experiment and paractise is the way to learn.

Glass can be put on the kiln's internal ceramic surface, on kiln paper to ensure a smooth finish. Put the lid on, turn on the kiln, and let it heat for about 35 minutes. You can look at the fusing progress through the opening.

When your piece is finished to your liking turn off the kiln. You may want to flash cool the kiln for a few seconds by lifting the lid and quickly replacing it, before letting the kiln cool to room temperature.

As with firing anything in any kiln, there's no definitive time-temperarture combination and, what works for a friend might not work for you. There's no substitute for learning by testing and from general experience.

KEUM-BOO COVERS

The red-brass covers are used for Keum-boo work. There are several excellent descriptions of Keum-boo on the internet so, rather than repeating them here, you need to research the subject. However, here's a brief description:

Keum-boo is a simple technique that bonds pure gold foil to another pure metal, such as fine silver, producing a rich gold colour. Because the gold foil is thin, the cost of adding pure gold to your work is low.

The gold is attached to the silver as a diffusion bond, an intermingling of molecules where the two metals meet. When pure metals are brought to the correct temperature, the molecules bond easily, when pressure is added, to create a permanent bond. This diffusion bond occurs far below the soldering temperature for either metal.

The kiln is hot enough if a lolly stick or cocktail stick chars in contact with the lid.

There are excellent descriptions of keum-boo on the internet so, rather than repeating them here, here's a brief introduction:

Newly-fired Art Clay and PMC are both pure silver, so don't need any surface preparation. Sterling silver must be depletion gilded by repeated heating and pickling before it can be used for keum-boo, to remove base metals from the alloy and leave a layer of pure metal on the surface.

The gold foil can be cut using a paper punch, a sharp modelling knife, or scissors. With scissors, it's often easier to cut the foil if it's between two thin pieces of paper.

Place it on the silver. If it drops off, pick it up with a damp finger or tweezers. After 25 minutes the kiln cover will be hot enough. Hold the piece still with tweezers and use a burnisher to press down the middle of the gold shape. Work outwards, smoothing the foil. The burnisher will heat up, so let it cool, or use a new one. You can re-heat the piece if an edge has not adhered.

When all the gold is in place, remove the piece from the lid and let it cool naturally. If you leave it on the kiln, the silver will continue to diffuse, and get paler.

Brush the piece with some soapy water, or use a little pumice powder. Tumbling generally creates a higher shine and the contrast between the silver and gold will diminish.

As with firing anything in any kiln, there's no definitive time-temperarture combination and, what works for a friend, might not work for you. There's no substitute for learning by testing and from general experience.

The photos show examples of gold leaf applied to Art Clay silver pendants. To look at the photos, hold your mouse over the appropriate zoom button below. The photos are 480px x 360px and about 94KB. If you're not on broadband, they'll take a short while to download.

Keum Boo Pendant.

Keum Boo Pendant.

The UltraLite is a very simple design, and unlikely to need servicing or repairing. If it doesn't heat up, there are only four possible causes: the mains socket isn't working, the fuse has failed, a wire has broken, or the element has burnt out.

To start, make sure the mains socket is working. If it is, take the plug apart, check the fuse, and confirm that the two wires are still connected and held firmly by the cable grip. If the kiln still doesn't work, the element will have burnt out. However, it's easy to fit a new one:

Before repairing your UltraLite for the first time, it's a good idea to make a drawing showing the position of the stand relative to the wire outlets. Then remove the central bolt that holds the whole kiln together. Whilst doing this, don't let the heating disc revolve as this may break the wires. The disc sits on three small removable ceramic supports, so be careful they don't fall out.

Carefully lift the heating disc out and check that both wires are connected. If they're not, they're not repairable. If they are, the element will have burnt out somewhere inside the ceramic disc.

Remove the plug, snip the nylon cable grip that clips the wires to the stand, and gently pull the wires out through the holes, again making sure that the three ceramic supports don't fall out.

Handle the new heating disc carefully as the element terminations are quite thin. Refit the three supports, the new heating disc, and the central bolt, making sure the disc doesn't revolve as you tighten it. Use the supplied cable grip to clip the wires to the stand as they were originally. Refit the plug, with one of the wires to live and the other to neutral. Check that the bolt is still tight.

All small, fast-heating, ceramic-fibre kilns, such as the UltraLite Kiln, have firing characteristics you need to be aware of. Due to the cut-out at the front, work placed near the front won't get quite as hot as work placed near the back. Also, putting the lid off-centre will effectively vent the kiln and reduce the temperature.

These variations won't affect metal clays, but might affect enamels and glass. So, if you work with temperature-critical materials or processes, you'll need to experiment at the beginning.

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

Working successfully with a kiln involves careful research, planned experiment, and repeated testing. It's important to learn how to creatively use unexpected effects, as things that work for your friends or teachers might not work in the same way for you. So, keep a firing log:

Buy a durable notebook. On a new page for every firing, draw a diagram of the shelf and the position of your work on the shelf. Put a few scraps at different places on the shelf to learn how things react. Describe the material, the shape of your work, the lid position, the firing time, and the end result.

A kiln log is vital if you're experimenting with temperature-sensitive materials, or working with coloured dichroic glasses, enamels, or glazes, and a skilled artist will use the log to advantage to re-create effects.

As with any creative process, there’s always room to experiment, rather than just rigidly follow someone else’s suggestions or rules. If something works well, you’ll probably want to repeat it.