Ceramic - Pottery Dictionary

by Susan Mussi



Click on the title to see more images

Kanna or tobikanna, Is a Japanese technique. It means “Leap of iron”
It’s a texture that can only be made as the work is turned on the wheel.

It creates an engraved continuous texture on a clay surface. Flexible metal tools are used and are held against the clay as the wheel quickly turns.

It is important to keep the clay in the correct state of moisture; if too soft the tool will enter into the clay too deeply and if too hard it cannot create a continuous pattern.

Working method;
When the piece has been turned and polished, center it again on the wheel. Holding the tool firmly between your fingers and with your arm firmly supported, start turning the wheel, indenting the tip of the tool. When you notice a strong vibration, you are creating a pattern with the Kanna method. Move the tool from the top to the bottom, changing its angle, the speed of the wheel and the pressure on the tool. They all affect the final result.
Since you cannot see the pattern that is being created because of the speed of the wheel, you may sometimes want stop the wheel to check the result. When you stop and restart, the pattern of the incisions changes, the texture is never the same when started again.

Decorative methods;
1) Apply slip over the piece, when it has lost its shine and can be touched without damaging it, put it on the wheel on a chuck and start to apply the tool at the top or bottom, starting gently.
2) Once the decoration on the clay is finished, oxides or slips can be applied into the grooves. When they are dry enough, go over the surface with a knife or very fine metal tool to clean up any roughness.
3) After being fired you can apply a coat of clear, transparent glaze that covers the surface to enhance the effects of the grooves and highlight the texture.

You can make your own tools or purchase them.
The tools must be flexible enough to create the pattern with the movement of the lathe.
With tin shears and gloves, cut the shapes you need out of scraps of metal or can lids, flexible aluminum or steel, pieces of metal band.
Razor blades also work if one side is cut into a round shape. Cover the opposite side with insulating tape to avoid it being sharp and to be able to put more pressure when making the incisions.

Note: Be careful with the tools, so as to avoid cutting yourself. You must not forget you are decorating with sharp tools and with the wheel turning at maximum speed.
It is not an easy decorative technique; it requires time to learn and to master the way to use the wheel and to use the correct tools. When one achieves the desired result, it vibrates like a piece of pottery. Every Kanna piece is different, it is almost impossible to create two identical pieces. The Japanese potter Shiga Shigeo was a great master of this technique.

Photos lent by: Nuria Pié, Shigeo Shiga, Ellen Rijsdorp, Monona Álvarez.
Link to author – Nuria Pié

Link to the viedo made by – Núria Pié



Kaolin calcined is the main way to use kaolin. In the glazes it is used to increase the firing temperature and reduce the dangers of cracking. In clays it makes it resistant to thermic shock.



Kaolinite also known as china clay, is a white natural clay that withstands high temperatures and is an essential ingredient in porcelain. It’s chemical composition is (Al2Si2O5(OH)4).



Kick wheel is the traditional pottery wheel that is turned and controlled with the pressure and movement of the foot by pushing a treadle back and forwards.
Read more about: Wheel (d) Foot and Electric



Click on the title to see more images

a) Different shapes in wood. b) Made with flexible steel. c) Made of steel, d) Flexible rubber for transfers. e) Serrated flexible steel scraper

Kidneys were originally made of rubber in the shape of a kidney; now there is a large selection of shapes, that vary in degrees of hardness and pliability and are made of materials, such as plastic, steel, etc. They are used on thrown and hand-built work for shaping, cleaning and smoothing surfaces, also for pressing clay into and onto a mold and special ones are made for flattening out transfers.

ca: FORN


Kilns; intermittent kilns are thermally insulated chambers or ovens made to produce and control temperatures in which different ceramic materials are fired. When functioning, they are shut so the internal temperature increases according to a schedule and when the process of firing has finished they are left to cool.

There are many types with different methods used for firing different materials; drying grains and wood; baking batter which turns into bread; firing clay into bisque which is hard, breakable but still porous; and vitrifying glazes into a layer of glass which stops the bisque being porous and makes the decoration permanent, giving depth and shine to the surface. A studio kiln is designed so heat can generate from 0º C up to 1350º C and an industrial one can reach much higher temperatures.

Kiln have changed in the last years before the heat was controlled by cones and now they are completely automatic. For information on cones Read more about: Cone – Pyrometric / Cone – Sockets / Cone – Witness

ca: FORN (1) Gas per ceràmica

es: HORNO (1) Gas por cerámica

Click on the title to see more images

1) Gas kiln: It is square, packed and opened from above. The lid is opened by pressing a pedal with your foot, and pulled outwards horizontally over two guides. It has two burners and the ventilating hood is on top of the kiln with a handle which allows the opening or closing of the entrance of air when firing is being reduced.

a) The kiln chimney. b) A sliding lid at the top, c) The gas controller. d) Nozzle to the gas burner with air controller. e) A pedal at the bottom to open the sliding door at the top

2 – 3) Gas kiln: It is round and packed from above. The top part is a lid that has a ventilating hole and above it is the hood; they are separated but attached by a small metal bar on each side and it has two burners. The vent hole has a handle to open or close the entrance of air.
The lid can be lifted and moved horizontally by pressuring your foot on top of the pedal which is underneath the kiln

4) Gas kiln the system is the same as 2 & 3 and it is still fabricated.
5) Gas kiln: A square one with a door at the front, the burners are placed at two lateral parts of the kiln and there are three for each side, the chimney and a ventilating hood are attached to the top with a handle for opening and closing the entrance of air.

Note: When used the ventilating hood or chimney are connected to a tube that goes outside. It can have a suction fan to draw out and expel the combustion of toxic gas, fumes and odors that have been created during the firing.
These kilns are made to be controlled manually or automatically and usually their maximum temperature is 1300º C.

Link to Hornos del Vales,S.A

ca: FORN (2) Exterior

es: HORNO (2) Exterior

Click on the title to see more images

The drawings and photos show and name the different parts of a kiln.

a) The kiln.
b) A drawing marking and naming all the sections of the kiln.
c) The lid covered with a board of wood to protect it and use as a table.
d) The lid made with fire bricks has a peephole in the center, a hinge that connects the lid to the main body, the bar that holds up the lid, two case clamps and the arm that holds the connection to the lid that connects the control box.
e) The top front of the kiln, the lid open, the bar that goes right round it, used when being moved and the top of the control box.

Link to Hornos del Vales,S.A

ca: FORN (3) L'interior

es: HORNO (3) El interior

Click on the title to see more images

There are five photos to explain the inside of a kiln.
a) The floor of the kiln.
b) The relation of the inside of the kiln to the program setting box outside, showing the peephole and the electrical connection, also the placing of the bricks and elements.
c) Two shelves, they help to preserve the floor.
d) A close up of the elements.
e) A close up of the peephole and the electrical connection.

ca: FORN (4) Caixa del piròmetre

es: HORNO (4) Caja del pirómetro

a) The control box.
b) The clip that goes down to confirm it is correctly shut.
c) Gives the temperature.
d) The button to turn it on and off.
e) The buttons that connect the different programs you have set up to use.
f) When the red button is pressed it is connected to the electricity and all the other lights come on.

ca: FORN (5) Exterior

es: HORNO (5) Exterior

a) The peephole.
b) Peephole plugs.
c) The lid hinges which are very strong.
d) The bar to hold when moving the kiln.
e) Clamp open.
f) Clamp shut.
g) Lid brace.

ca: FORN (6) Exterior

es: HORNO (6) Exterior

a) The arm to hold the lid up.
b) The hook at the end of the arm.
c) The joining point of the arm.
d) Security connection closed and connected.
e) Security connection opened and unconnected.

ca: FORN - Continu

es: HORNO - Continuo

Continuous kiln is also known as tunnel kiln. The ware is put on to bats, the bats are on rollers which turn and slowly move the ware through a long tunnel and as it moves it goes through the whole process of firing. As it moves, the heat increases and when it reaches the central portion it will be at the hottest part, the heat required for that particular type of ceramics. It goes on moving but with the temperature gradually reducing until it leaves the kiln at room temperature.

ca: FORN - Fums

es: HORNO - Humos

Kiln fumes appear during the early stages of firing while the kiln is heating up. The evolution of the clays and glaze forms vapors which can be inhaled and some are toxic. Make sure you know what you are playing with, that your ventilating systems are good and if necessary wear a mask. When firing transfers, the smell is awful. The first time I fired them I did not warn my neighbors and they all came down to tell me that the sewage pipe that went under my patio must be obstructed or blocked. In large kilns, ventilators or chimneys are usually installed but not in small ones.

ca: FORN – Accessoris

es: HORNO - Accesorios

Kiln furniture applies to all the implements used to pack a kiln to its full capacity, shelves, cranks, stilts, etc.

The dictionary has each piece of kiln furniture in two different places, alphabetical by its name and here it has all the illustrations, in alphabetical order so that you can find what you want rapidly, without knowing its name. If you want more information go to its section by clicking on to its name, which is in red below and in these sections is the name in the other two languages.

Read more about: Bits / Cranks / Cranks walls / Kiln shelves / Pip / Plate setters / Plate shelf / Saddle / Spur / Stilts / Tile shelves / Tube props

ca: FORN - Verificador de calor

es: HORNO - Verificador de calor

Click on the title to see more images

Kiln heat controller is a thermocouple which consists of a porcelain sheath that is passed through the hole at the side of your kiln. The length of the sheath depends on the width of the wall of your kiln. It transfers the temperature of the kiln on to the pyrometer, which interprets it into digits. It can be attached to a temperature controller and depending on its quality, it can completely control the process of firing, from beginning to end.

ca: FORN - Historia

es: HORNO - Historia

Primitive man knew that leaving clay in the sun hardened it and when he learnt how to make fire he realized that putting clay for several hours on a bonfire, with the heat all round, made it become even harder and stronger and that many pieces could be fired together. As man evolved over thousands of years, so did the method of firing. The next step came with the realization that the earth did not burn and held in the heat. Pits were dug into the ground and layers of flammable organic material such as wood and straw were laid on the floor. The sun-dried pots would be stacked on top, then more organic material round the sides and finally broken pieces of fired pottery over the top. When fired, the earth walls and the broken pottery held in the heat so firing became quicker and reached a higher temperature.

The next stage of progress after pit firing was to an updraft kiln and it is believed that this started in Egypt over 7000 years ago. Man realized that if the earth and the walls of a pit could hold the heat then a kiln could be built up with stones, broken pottery and mud-clay. The first updraft kiln was oval in shape, like a U upside down, with an opening at the bottom to use as a stoke hole. The roof was a half circle and completely sealed off for firing and had to be broken to unload. This method spread throughout the Mediterranean countries, Greece, Rome, Crete and the Middle East.

Great improvements came in the next stage; the kiln was separated into two sections by a floor. The bottom was for the wood for heating, it had open spaces and doors so wood could be continually added. The ware being fired was on the top floor and had a chimney so the gases could escape during the early hours of firing. Both the chimney and the stoke holes had separate blocks of bricks to cover them during the firing; this helped to control and increase the heat.

The downfall of the Roman and the growth of the Arab Empire brought great changes in the understanding of ceramics, the use of glazes and colors made from valuable metals. There came the understanding that clay firing and glaze firing had to be separate as gases from the clay damaged the colors.

In Spain, the kilns used for firing were known as Arab Kilns and they created the heat by wood-firing. They were large brick square structures with two floors. The bottom floor of the kiln was for the wood-fire and the top for the objects to be fired. The firing time depended on the size of the kiln and could take up to 24 hours. Firing started with a low fire, gradually heating up until it reached the required temperature, this point being judged by looking through the pin-holes to see the color of the heat and slipping out test pieces to see the evolution of a colored glaze. The timing with clay was not so important, as slightly over firing does not affect it, but with colors, over firing can completely destroy all the work. The firing process demanded men to work non-stop, filling the kiln with wood, checking that the temperature was continuously increasing at the same degree throughout the kiln. When the kiln reached the correct temperature it was left to cool, opened, and each piece of bisque was taken out and checked. It was with this method of firing that all the beautiful Luster was produced.

The energy for kilns during many centuries was the heat from burning wood, but now there are many different types of kilns, makes, sizes, designs, firing and the energy for heating can be electric, gas, wood, coal and oil. They are made for use with an automatic temperature controller or, if electric, with cones. Some are known by their method of glazing like Raku and Salt and the understanding of kilns, with their many differences, can become a specialty in itself.

ca: FORN - El meu forn

es: HORNO - Mi horno

Electrical kilns can be used with very little industrial installation. Make sure your power supply is strong enough, that it has good individual electrical wiring with its own fuse box and that the room has sufficient ventilation. There must be enough space around the kiln for packing and maintenance. If it opens at the top you must have access at every side and if at the front you must be able to open the door completely to 180º and have access to the back for repairing. There are two main classes of kilns, one which can reach 1100º C and another up to 1350º C. When your kiln is new follow the maker’s instructions, test it once or twice before firing products.

I use the modern, electric kilns as my workshop is not classified as industrial and as the voltage is high, I use only one kiln at a time. Kilns made for ceramics are now made with a metal coat on the outside and walls, floors and roof made of refractory brick on the inside. They are octagonal inside and round on the outside. I chose them because they consume very little electricity for their size and because they open at the top. The advantages of this are that you can look in from above and check that everything is placed correctly and not touching or wasting space and that they can be easily moved. This is not the case when using a kiln that opens from the front. When it is automatic, you can set your kiln to the temperature and length of time required in relation to the heat needed for what is being fired. You can program this data into the memory of the kiln with a number, so that this setting can be put in motion by turning to the number needed for that firing. Once started, the process of heating is automatic and when it reaches the temperature it turns off, so once set, you can forget it.

ca: FORN - Habitació

es: HORNO - Habitación

Click on the title to see more images

This is a the kiln room: on the left there are shelves full of pieces used in firing and on the right the kilns, boxes to keep the kiln furniture, the work prepared to be fired and the boards they are kept on. The last two photos show a kiln being packed; a side view showing the kiln door and a front one, how it is being packed.

Read more about: Kiln (1)

Photos taken in the workshop of Sot: www.ceramicasot.com

ca: FORN – Plaques

es: HORNO - Placas

Kiln Shelves: there are many types, makes, shapes and sizes and their purpose is to make floors. Tube props are built up to the height required and the shelves are put on top. This allows work to be supported at different heights. Note: They are known as bats.

ca: FORN - Prova de Colors

es: HORNO - Prueba de Colores

Click on the title to see more images

Kiln test colors: Small kilns for testing colors are useful if you make up your own colors, but they do have problems because as they are small, the heat rises quicker than a normal kiln and I find this alters the colors slightly. This kiln takes bits of bisque 5 cm wide by 15 cm long. Mark them on the back with a code; lay them on top of another piece of bisque which is used as a tray and is slightly larger to protect the kiln, should the colors run. Firing up to 1000º C takes 50 minutes. The box behind the kiln is a transformer as it was made to use with a weaker electrical current 110 volts. This shows you how old it is. Now all Europe has basically the same voltage, 220V. This sufficient for what I need but now you can buy very good industrially made ones.

The photos are in the order of working.

ca: FORN – Carretons

es: HORNO - Carretillas

Click on the title to see more images

Kiln Trolleys, there are two types:
a) A small one with a floor on wheels that can go under the kiln and the arms carry the product to be fired, so that they can be moved up into the kiln and placed correctly.
b) A kiln that has a movable floor so that it can be mounted with shelves and packed, while it is outside; this means you can work on four sides and on each floor separately. When completed, as it is on wheels, it can be pushed back into the kiln and attached. These facilities are only available with large industrial kilns.

ca: FORN - Tipus

es: HORNO - Tipos

Anagama kiln – the Asian anagama kiln has been used since medieval times and is the oldest style of kiln in Japan. This kiln usually consists of one long firing chamber, pierced with smaller stacking ports on one side, with a firebox at one end and a flue at the other. Firing time can vary from one day to several weeks. Traditional anagama kilns are also built on a slope to allow for a better draft.

Bottle kiln – a type of intermittent kiln, usually coal-fired, formerly used in the firing of pottery; such a kiln was surrounded by a tall brick hovel or cone, of typical bottle shape.

Electric kilns – kilns operated by electricity were developed in the 20th century, primarily for smaller scale use such as in schools, universities, and hobby centers. As these electrical appliances improved in dependability, they became a valuable tool for artists as well. The atmosphere in most designs of electric kiln is rich in oxygen, as there is no open flame to consume oxygen molecules, however reducing conditions can be created with appropriate gas input.

Microwave Assisted Firing – this technique combine microwave energy with more conventional energy sources such as radiant gas or electric heating in order to process ceramic materials to the required high temperatures. Microwave-assisted firing offers significant economic benefits

Modern kilns – with the advent of the industrial age, kilns were designed to utilize electricity and more refined fuels, including natural gas and propane. The majority of large, industrial pottery kilns now use natural gas, as it is generally clean, efficient and easy to control. Modern kilns can be fitted with computerized controls, allowing for refined adjustments during the firing cycle. A user may choose to control the rate of temperature climb or ramp, hold or soak the temperature at any given point, or control the rate of cooling. Both electric and gas kilns are common for smaller scale production in industry and craft, handmade and sculptural work.

Top-hat Kiln – an intermittent kiln of a type sometimes used in the firing of pottery. The ware is set on a refractory hearth, or plinth, over which a box-shaped cover is then lowered.

Arab Kilns: In Spain the kilns used for firing were known as Arab kilns, they were brought to Spain by the Arabs and used in their kingdom of Granada. They created the heat by wood-firing and were large brick square structures, with two floors. The bottom floor of the kiln was for the wood-fire and the top for the objects going to be fired. The firing time depended on the size of the kiln and could take up to 24 hours. It started with a low fire, gradually heating up until it reached the required temperature. This point was judged by looking through the pin-holes to see the color of the heat and slipping out test pieces to see the evolution of a colored glaze. The timing with clay was not as important as slightly over firing does not affect it but with colors over firing can completely destroy all the work in the kiln. The firing process demanded men to work non-stop, filling the kiln with wood, checking that the temperature was continuously increasing at the same degree throughout the kiln and checking when the kiln reached the correct temperature, after which it was left to cool.
Link to Kilns Robert Compton Pottery

ca: FORN – Ventilació

es: HORNO – Ventilación

Click on the title to see more images

Ventilation for an electric kiln for small workshops is made through two peepholes in the wall and one vent hole in the lid. The vapors escape through the holes during the first stage of firing and these are closed with plugs when the firing of clay and enamels reaches the temperature of around 600° C. This helps to conserve energy until the kiln arrives at the final temperature and during this period no fumes or odors are released. Electric kilns can be without ventilation, ones that are packed from above do not have vent holes like the ones that open at the front nor do they have chimneys as electric firing produces little contamination.

Electric kilns with ventilating tube installations help to compensate for this rising heat by creating a flow of air moving back down the kiln chamber. As the air moves in a downward direction it is also deflected by ware and shelves causing turbulence. This turbulence helps move heat to cooler areas of the kiln like the center. When you are firing in an electric kiln you are firing in an oxidation atmosphere, which helps bring in more oxygen and flush out fumes which can form a reduction atmosphere. Your elements will last longer, your glazes will be clearer and brighter and you will help prevent glazes migrating between pieces.
Read more about: Ventilating tubes in www.skutt.com

Ventilation for a gas kiln: gas kilns are manufactured with a chimney that has an electric fan, a metal tube that is connected to the outside and some have arms that join them to the wall or floor
a) A hood is square, has a large entrance, the wall narrows vertically in diameter as it gets higher and has a short neck at the top so it can be attached to a tube. They are not attached to the kiln, but directly above it.
b) The chimney is the wide tube that is connected to the neck of the hood and to the outside.
c) The chimneys have a suction fan, which is the system for the reduction and combustion of toxic gas, fumes and odors that are expelled from kilns. They can be connected to a pump powered by electricity, or have a direct exit through the tube to the outside.
d) If large, the tube is attached to the wall or ceiling.

For big industries that have large gas kilns, suction fans are an important feature, due to the large amount of clay they have in each firing.
Read more about: Chimney



Kiss is when pieces being fired touch and stick together. This will happen with whatever a glaze touches and separating will leave the pieces damaged and difficult to repair.



Kitchen Paper; is very useful for cleaning many things, as it is always dry and clean and can be thrown away. I use it when working with very light colors as the cloths you normally use get very dirty and a small dark mark on a place, like a face can spoil the whole picture. It is also used for cleaning silk screens. When the screen you are using is correctly placed it can get blocked with paint and you have to clean it but do not want to dismount it. The best solution is a bowl of water and a roll of kitchen paper.



Kitchen timer is like a clock that can be set to ring when a certain period of time has passed. I have a small kiln for firing trial colors which has no time control and for this it is excellent.



Knead: to prepare clay so it has the right pliability for the required work. It is done by pushing the clay down and outwards into a thick rectangular shape, then folding it lengthwise, turning it and flattening it out again
Read more about: Clay (1) Kneading



Knob: the name for a small protruding part at the top of a lid or on the side of a basin or vase which is held when picking the piece up. It is a small handle and can be constructed as part of a lid or added later. In the case of a jar, is always added.
Read more about: Lid (e) – Knobs