Table of Contents
The terms oxidation and reduction refer to how much oxygen is in the kiln’s atmosphere while the kiln is firing. An oxidation atmosphere has plenty of oxygen for the fuel to burn. A reduction atmosphere occurs when the amount of available oxygen is reduced.
What is reduction firing?
A method of firing stoneware where the kiln air intakes and burners are set to restrict or eliminate oxygen in the kiln such that metallic oxides convert to their reduced metallic state.
What is an oxidizing firing?
A firing where the atmosphere inside the kiln has sufficient supplies of oxygen to react with the glaze and clay body surfaces (and thus produce the colors characteristic of this). Electric kilns are synonymous with oxidation firing.
What is reduction firing in an electric kiln?
Reduction causes most ceramic materials (such as your glazes) to melt faster. If you want more time in reduction without more heat work, reduce the amount of fuel (you may also need to reduce air-intake and close the exit flue or damper even more) so that the kiln is soaking, rather than gaining heat.
What are the methods of firing?
This article will give an easy-to-understand account of 7 of the most common methods of firing clay. The methods covered are electric, gas, wood-burning, soda firing, raku, sawdust, and lastly pit firing. Each method involves different techniques, producing very different types of ware.
How do you fire a reduction?
In reduction firing, oxygen is prevented from interacting with the glazes during glaze maturation. This is done by adjusting the fuel in a gas kiln, or by adding organic material such as in Raku. As the organic material burns it uses up oxygen, leaving an oxygen-less environment.
Should a bisque firing be in reduction or oxidation?
Many materials used in ceramics contain carbonaceous matter, including organic carbon and inorganic carbon from clays, whiting, dolomite, and talc. This carbon must be burned out (oxidized) during the bisque firing to ensure the best results possible in glaze firings.
Why is raku a reduction firing process?
More About Reduction in Raku Firing However, raku is a low fire process and the kiln does not reach high enough temperatures to cause reduction. The result is that carbon monoxide draws oxygen out of clay and glaze in the kiln. This causes the clay and glaze to become denser and to intensify colors and textures.
What is salt firing?
Salt firing is a process where unglazed ware is fired to high temperatures and salt fumes are introduced into the kiln chamber (normally by a spray in the burner ports). The sodium in the salt forms a vapour cloud in the kiln. Salt glazed ware typically has distinctive marbled and variegated surface effects.
What are the 2 basic types of kiln atmospheres?
In the broadest terms, there are two types of kilns: intermittent and continuous, both being an insulated box with a controlled inner temperature and atmosphere. A continuous kiln, sometimes called a tunnel kiln, is long with only the central portion directly heated.
Can you saggar fire in an electric kiln?
We typically fire these saggars in a raku kiln, but can be done in an electric or a pit. We pack the kiln with pieces ensuring there is airflow around each piece. We fire until the foil loses its sheen, its shine.
What happens during reduction firing iready?
Reduction firing is when the kiln atmosphere, which is full of combustible material, is heated up. “Reduction is incomplete combustion of fuel, caused by a shortage of oxygen, which produces carbon monoxide” (Arbuckle, 4) Eventually, all of the available oxygen is used.
What is an example of slow oxidation?
As its name indicates, this is a slower version of oxidation where products are slowly ruined over time. Examples include products becoming spoiled and discolored, metal corrosion, rusty car doors, and foods turning moldy.
What does reduction mean in pottery?
The terms oxidation and reduction refer to how much oxygen is in the kiln’s atmosphere while the kiln is firing. An oxidation atmosphere has plenty of oxygen for the fuel to burn. The reduction process, when oxygen is leeched out of your kiln atmosphere and pottery, can change the texture of your clay.
What is oxidation in Kiln?
Oxidation occurs when there is an excess of oxygen. As the kiln heats up compounds in the glaze break off and oxygen attaches itself to the glaze and clay. This causes metals in both to oxidize. Reduction occurs when there is a deficit of oxygen.
What are the three types of ceramics?
There are three main types of pottery/ceramic. These are earthenware, stoneware and porcelain.
What kind of clay is used for barrel firing?
If you prefer, you can use terra sigillata on a bone dry piece of pottery to achieve a nice shine. To apply terra sigillata, center the pot on a banding wheel and choose a soft brush such as a hake brush or a makeup blush brush. Coat the pot with two to three even coats of terra sigillata.
What is hand firing?
Hand-fired grates were made of cast iron. They varied in design to suit the type of fuel to be burned. The air openings in the grates varied from 1/8 to 1/2 in in width, and larger air openings were used for burning bituminous than for burning anthracite coal.
Can you soda fire in an electric kiln?
What kilns can I soda fire in? Any kiln that uses carbon fuels (propane, gas, wood) Soda is corrosive, and will destroy elements in an electric kiln quickly. Any kiln design that fires well (catenary or sprung arch, top loading, up draft, down draft, cross draft, etc)May 28, 2019
How many types of kilns are there?
There are two types of kilns, the continuous or tunnel kiln and the periodic or intermittent kiln. Continuous kilns are continuously firing and are never cool. The items that are to be fired are placed into cars and then slowly move through the kiln. Continuous kilns are mainly used for industrial manufacturing.
What is firing in clay?
FIRING- The process of heating clay work in a kiln to at least a glowing or white heat. Firing permanently transforms the clay to a rock-like state and melts glazes. FLOOTING- Scoring (scratching) leather-hard surfaces, applying slip, and joining leather-hard pieces.
