Is a tank pressured with steam, in order to stress the moisture expansion of the body, therefore check the crazing resistance of a glazed sample.
- Black core
Is a greyish or black part inside the product itself, due to incomplete degasification or combustion of organics trapped in the middle of the piece and creating locally reducing atmosphere.
- Blunger (Blunging)
Tank with mixer for the production of clay slips or slurries.
- Body, Ceramic
Workable mixture of clays and non-plastic materials with properties suitable for firing, from which ceramic products are made.
- Casting rate
Is the rate of thickness formation during the casting.
- Casting Slip
Ceramic body composed of raw materials mixed with water and deflocculant to form a slurry.
Calcined clay or kaolin used as an inert raw material to improve properties (reduces deformation and shrinkage) in refractories, FFC sanitaryware and similar products.
- Creeping (Pyroplasticity or deformation)
Is the tendency of the material to deform slowly under its own weight, or under the stress of temperature. Creeping is closely linked to the pyroplasticity of the material (plastic behavior when heated).
Reagent used to disperse agglomerates to achieve fluid slips at higher density.
- Fire clay (FC) / Fine fireclay (FFC)
Are products containing chamotte. The use of chamotte allows lower shrinkage and deformation, thus the production of bigger items (sinks, shower trays, washbasins…).
Is the ability of the slip to let the water going through the forming cake. It’s in closely link with the casting rate. Permeability is measure with a Baroid.
- Plaster / Gypsum
Gypsum is the natural material (CaSO 4, 2H 2 O), precursor of plaster (CaSO 4 ,1/2H2O),used to prepare plaster molds.
- PSD / Particle Size Distribution / Granulometry
Is the measurement of the size distribution of a collection of grains, particles. Could be measured with sieves, Laser granulometer, X-Ray granulometer.
Amount of particles rejected at a determined size, could be on the sieve during the process, or by calculation in the lab (see PSD).
Is the study of flow properties of a liquid, like casting slips, engobe and glazes. Main outputs in ceramics are viscosity an thixotropy.
- Solid percentage / Solid content
Is the mass percentage of equivalent dry material contained in a slurry (slip).
- Thermal Expansion / CTE (Coefficient of Thermal Expansion) / Dilatation
Reversible or permanent change in the dimensions of a body exposed to heat. Measured with a dilatometer.
Property of a suspension to increase in viscosity without stirring, due to a buildup of structure within it, which is usually reversible by agitation.
Is the measurement of a fluid’s resistance to flow. Most common devices for the measurement : torsion viscometer (Gallenkamp), rotational cylinder.
- Vitreous china
Is a vitrified body, usually with a fired water absorption below 0.5 %. Used for closets and small pieces.
Progressive reduction in a body’s porosity due to heat treatment and fusion, during which a glassy or non-crystalline material is formed.
- Water absorption
Is the quantity of water that the body is able to absorb in specific conditions (usually boiling water during 1 hour). Calculated in mass of water / mass of body.
Should be below 0,5%, around 8-9% for fine-fireclay.
Slight raised crescent shape on the inside wall of slip-cast ware.