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Words beginning with B
Basic
See Acidic.Bat
Many people in Europe use the term 'bat' to refer to kiln shelves (i.e. UK). Thus 'bat wash' is kiln wash. However in North America, 'bat' most often refers to wood, plastic, or plaster disks which are used on the potters wheel. A bat is held in place by pins, an interlocking arrangement, or glued on by slip. Ware can then be thrown on the bat and the whole thing removed to make another piece.Bisque, bisquit
The practice of prefiring ware without glaze to make it impervious to water, easy to handle, or vitrify it. Glaze is then applied and it is fired again. 'Low' bisque firing is typical for pottery and ceramics while vitrified bisque is done for bone china and some types of stoneware. Low bisque should be fired as high as possible to burn away all carbonaceous matter, yet low enough to provide enough absorbency to make glaze application easy. 'High' bisque firing is done to mature the body (i.e. bone china) and subsequent firing is usually done to apply a low fire glaze. Such glazes must have special additives to make them gel and stick to the ware (i.e. calcium chloride, gum); these glazes take much longer to dry.Black coring
Black coring usually occurs during a reduction firing and is a result of fast firing and/or lack of oxygen in the kiln between 700 and 900C (usually in the bisque firing). If body carbon fails to oxidize to CO2 it steals oxygen from Fe2O3 (reducing it to FeO, a powerful flux.) This FeO will then flux the body, sealing it and preventing the escape of remaining carbon in the body. This produces the characteristic 'black core' you see on ware cross section. The more iron in a body, the greater the risk of this problem if firing is not right. Once iron is reduced to it is very difficult to reoxidize it back to Fe2O3.
Note that electric kilns can also produce this problem, depending on the carbon and iron content of the clay, density of the pack, available airflow, and speed of the firing.Bloating
Bubbling that occurs in clay bodies if they are overfired. Aggravating conditions include the presence of mineral particles that generate gases during the overfiring stage and the presence of excessive carbon not burned away by oxidation firing.Blunging, mixing
Mechanical mixing of a clay slurry. Blungers of all different types are available. Some are simply a high-speed propeller on a shaft, others employ complex arrangements of paddles and container shapes. Clay slurries require the application of considerable amounts of energy to achieve a slip in which water has penetrated well between all particles.Body, clay body
A mixture of raw and/or refined clays with possible additions of flint as a filler and feldspar as a flux. In typical vitrified bodies the larger grains of quartz and clay remain unmelted giving rigidity to the mass while the fluxes melt to a glass which binds these grains together. Earthenware bodies develop much less glass bonding and depend more on sinter-bonding and are therefore weaker.Borosilicate
A generic term referring to a glaze or glass that contains significant boron. High temperature glazes do not require boron, infact it is detrimental to hardness and stability. However and middle and lower temperature, boron is a necessary glaze component to achieve necessary melting. Boron is sourced mainly from frits and these are thus called borosiliate frits.Buff stoneware, buff ceramicclay
'Buff' is a term used to describe the color of a non-vitreous or semi-vitreous fired clay that has enough iron to take away its claim to being white yet not enough to make it a brown or red burning ceramic. Buff coloration is generally a straw color or yellowish white. Grey-white firing bodies are not usually referred to as 'buff' firing because the grey coloration is associated with vitrification, especially in reduction.
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