Ceramic Dictionary

KANNA

ca: KANNA

es: KANNA

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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 on a clay surface an engraved continues texture. 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 continues paten.

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, it is because it is creating 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.
You cannot see the pattern that is being created because of the speed of the wheel, if you want to you can occasionally stop the wheel to check the result. When you stop and restart the pattern of the incisions changes, the continuation is never the same.

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

Tools.
You can make your own tools or purchase them.
The tools must be flexible enough to create the pattern in the movement of the lathe.
With tin shears and gloves, cut into desired shapes with debris or lids of cans, flexible aluminum or steel, pieces of strap.
The blades also work if one party is cut into round shape. Secure with tape the opposite side to avoid being sharp and able to put more pressure on 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 whith the wheel turning at the maximum speed.

Addvice.
It is not an easy decorative technique; it requires time to learn and to dominate the way to use the wheel and to use the correct tools. When one achieves the result desired, vibrates like a piece of pottery. Each Kanna has a different result, it is almost impossible to create two pieces the same, the Japanese potter Shiga Shigeo was a great master of this technique.
Illustrations; (a) Núria Pié. (b-c) Shigeo Shiga. (d-e) Ellen Rusdorp.

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KAOLIN

ca: CAOLÍ

es: CAOLÍN

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

KAOLIN CALCINED

ca: CAOLÍ CALCINAT

es: CAOLÍN CALCINADO

Kaolin Calcined

KAOLIN de GEORGIA

es: CAOLÍN DE GEORGIA

Kaolin Georgia

KICK WHEEL

ca: TORN A PEDAL

es: TORNO A PEDAL

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. See: Wheels.

KIDNEY

ca: LLENGÜETES

es: LENGÜETAS

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

Kidneys were originally rubber in the shape of a kidney; now there are 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 flatting out transfers.

KILN (1)

ca: FORN (1)

es: HORNO (1)

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 0ºC up to 1350ºC and an industrial one can reach much higher temperatures.

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

KILN (2) Outside

ca: FORN (2) Exterior

es: HORNO (2) Exterior

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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 it 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.

KILN (3) Inside

ca: FORN (3) L'interior

es: HORNO (3) El interior

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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 elments.
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.

KILN (4) Control box

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 light come on.

Kiln (5)

ca: FORN (6)

es: HORNO (5)

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.

Kiln (6)

ca: FORN (5)

es: HORNO (6)

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 conected.
e) Security connection opened and unconnected.

KILN - Continuous

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.

KILN - Fumes

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. With large kilns, ventilators or chimneys are usually installed but not with small ones.

KILN - Furniture

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 are the name in the other two languages.

See: Bits – Cranks – Cranks walls – Kiln shelfs – Pip – Plate setters – Plate shelf – Saddle – Spur – Stils – Tile shelves – Tube props

KILN - Heat controller

ca: FORN - Verificador de calor

es: HORNO - Verificador de calor

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Kiln heat controller is a thermocouple 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.

KILN - History

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 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.

KILN - My kiln

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.

KILN - Packing

ca: FORN – Càrrega

es: HORNO - Carga

For packing kilns See: Kiln – Furniture and the following four sections on packing Packing (a) Kilns / Packing (b) Clay to bisque fire / Packing (c) Decorated work / Packing (d) Process

KILN - Shelves

ca: FORN – Plaques

es: HORNO - Placas

Kiln Shelves: There are many types, makes, shapes and sizes and they are 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.

KILN - Test colors

ca: FORN - Prova de Colors

es: HORNO - Prueba de Colores

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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 1000ºC takes 50 minutes. The box behind the kiln is a transformer as it was made to use with less electrical force 110. This shows you how old it is now all Europe is basically the same 220. This sufficient for what I need but now you can buy very good industrially made ones.

The photos are in the order of working.

KILN - Types

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 depends 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 when the kiln reached the correct temperature after which it was left to cool.
Link to Kilns Robert Compton Pottery

KILN - Ventilation

ca: FORN – Ventilació

es: HORNO – Ventilación

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Ventilation for an electric kiln: Ventilation for electric kilns for small workshops is made through three small holes, peepholes the two in the wall and vent hole the one in the lid. The vapors escape through the holes during the first stage of firing and are closed with plugs when firing of clay and enamels reaches the temperature 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 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 gives out little contamination.

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 as it gets higher, narrows vertically in diameter 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 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.

KILN - Wash

ca: FORN - lletada

es: HORNO - Lechada

Kiln wash is a coating of refractory powder made up of half flint and half kaolin that is mixed with water and painted on kiln shelves to prevent ware and accidental running of glazes from fusing to the shelves.

KISS

ca: ENGANXADES PER CONTACTE

es: UNIDAS POR CONTACTO

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 TIMER

ca: TEMPORITZADOR DE CUINA

es: TEMPORIZADOR DE COCINA

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

ca: PASTAR

es: AMASAR

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, turn and flatten out again
See: Clay (1) Kneading

KNOB

ca: TIRADOR

es: TIRADOR

Knobs: 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, it always added.
See: Lid (e) – Knobs