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Words beginning with E
Earthenware
A clay fired at low temperatures (cone 010-02) where it does not develop maturity (vitrify). Earthenwares are porous and therefore not as strong as stonewares and porcelains (sintering is the primary particle bonding mechanism). Earthenware glazes are usually very bright colored and if the glazes are properly fitted, earthenware can be quite strong and functional.
Terra Cotta is a special type of earthenware where red burning clay is used.Encapsulated stains
Certain coloring oxides are toxic and stain companies have found a way to embed particles of stain into transparent zirconia frit particles. The zirconia melts at temperatures higher than typical glazes so the effect is "encapsulation", even though no true capsule exists. These stains cannot be ball milled (for obvious reasons) and there is some need for caution in high temperature highly fluxes glazes. The best example of encapsulation is Cadmium red stains. While good red colors can be achieved it is expensive and a much higher proportion of stain is needed to get a bright color, up to 25%.Engobe
A white or colored slip applied to clay as a coating or by slip trailing, usually at the leather hard stage.
Engobes are formulated with less clay content than slips. A slip shrinks with the ware as it dries. A engobe formulated for application to dry or bisque ware cannot shrink excessively. Also, a higher percentage of flux in an engobe helps it to bond to the surface during firing. A slip, on the other hand, bonds to the surface during drying by the interlocking of the flat clay particles at the interface between the damp clay and wet slip.Eutectic
The lowest temperature at which a mix of two materials will melt. Often the temperature is an anomaly, that is, it is much lower than the melting temperatures of only slightly different mixtures.
Lead-tin solder is an example. Lead melts at 327C, tin at 231C. The lowest melting combination is 67 lead, 33 tin (180C).
Non-eutectic mixtures have a melting or softening range. Such mixtures do not flow well until thoroughly heated past the softening range. This softening phenomenon is what makes glazes hang onto the ware.
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