Page 15 - My FlipBook

That we may be better acquainted with certain terms used in dental
porcelain art, let us consider the following glossary:
Dental Porcelain. A solidified mass composed of
_ . . , i, one or more silicious suljstances susiiended in a fused
Ccchnical Ccrms. .,. '
silicate.
Silex. The oxid of silicon, which is a white, highly fusible, mod-
erately hard, crystaline substance.
Kaolin. The hydrated silicate of aluminum, which is white, opaque,
refractory clay, resulting from the decomposition of feldspar.
Feldspar (Orthoelase). The silicate of aluminum and potassium with
varieties and in which the aluminum is partially replaced by sodium. It
is a translucent, moderately high fusing substance, and varies in color.
Fusion. A chemico-physical change produced by subjecting porce-
lain to enough heat units for a given time to cause a rearrangement of
the molecules, with partial vitrification, and a glaze of the surface of
the mass.
Firing. The process of heating porcelain in a furnace.
Soft Biscuit. A state resulting from heating porcelain sufficiently
to harden it only enough to permit it to be carved.
Hard Biscuit. A state resulting from heating porcelain sufficiently
to harden it enough to prevent carving, but yet not enough to produce
shrinkage.
High Biscuit. A state resulting from heating porcelain sufficiently
to obtain shrinkage, but not enough to produce glaze.
High Fusing Porcelain. A porcelain which requires more than five
minutes to fuse at a heat not exceeding 2,000 degrees F.
Lozv Fusing Porcelain. A porcelain which requires less than five
minutes to fuse at a heat not exceeding 2,ocx3 degrees F.
Basal Ingredients. Those ingredients which form the fundamental
mass of the porcelain. Viz. : silex, kaolin, and feldspar.
Flux. A material used to increase the fusibility of porcelain.
Pigment. Metals or their oxids which, when added to porcelain
and heated to a high degree, will produce a definite hue of color.
Frit. An intense pigment which is fused with feldspar and flux and
then ground to a fine powder and used as the coloring material for
dental porcelain.
Basal Body. Porcelain composed of the basal ingredients and the
pigment. This includes such terms as block body, tooth body, etc.
Foundation Body. A basal body, the fusibility of which has been
increased by the addition of a flux, and one which requires more than
two minutes to fuse at a temperature of 2,100 degrees F.

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