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also breaks up the uniformity of color so often noticeable when an inlay
is constructed of a mono-chromatic porcelain.
Another method is to build inlays in sections.
Buildina in Sections. 1 he foundation is applied and fired to a high biscuit.
The gingival third is covered with an enamel that
lias the same hue as the tooth in that location. In case this section of the
tooth shows a hue of gray or brown, a thin layer of enamel of the re-
quired hue is applied and fired to a high biscuit before the enamel of the
predominating hue is applied. The middle third is then covered with
the enamel of the desired hue and hard biscuited. The incisal third is
built with an enamel that approaches the hue of the incisal third of the
natural tooth and fired to a hard biscuit, after which a uniform layer of a
neutral color is applied and fused.
There are conditions, however, under which it is
mixing Colors. deemed advisable to mix colors in the construction
of inlaws. While this is not necessary in the greater
number of cases, the author has found that the mixing of colors some-
times yielded better results than he could secure by other methods of
application. Some colors may require modification. The yellows, for
example, may need to be toned with the grays ; the grays brightened by
the addition of yellow ; or the blues may be lightened by the admixture
of green, or saddened by the addition of a gray.
In mixing two porcelains or in applying them in layers, it must be
borne in mind that the resulting color is primarily due to the power of
the combined porcelains to absorb or transmit light. When the two por-
celains are mixed, or when they are applied in thin layers, the resultant
color is that which is transmitted by both colors in common. When two
colors, as blue and yellow, are combined, it is found that green is the only
color that is common to both of them, and this is, therefore, freely
transmitted or reflected; the others being absorbed. If a layer of blue is
placed over a layer of yellow, the light, in passing through the blue por-
celain, loses its red, orange, and yellow rays, which are absorbed, and are
not, therefore, transmitted ; while green, blue and violet are transmitted
to the yellow, which absorbs the blue and the violet, leaving the green
to be transmitted or reflected. The purity of the green is dependent upon
the purity of the yellow and the blue, and by the thickness of the layers.
\Mien blue is used to build the incisal portion of an inlay, the yellow
foundation should extend only to the point at which the blue is to begin
for the blue will have a greenish hue, if it is applied over the yellow.
When yellows and blues are applied over grays or browns, the underlying
colors have the quality of saddening the overlying ones, because the trans-
mitted rays from the yellow and blue are largely absorbed by the gray
or brown.
91
also breaks up the uniformity of color so often noticeable when an inlay
is constructed of a mono-chromatic porcelain.
Another method is to build inlays in sections.
Buildina in Sections. 1 he foundation is applied and fired to a high biscuit.
The gingival third is covered with an enamel that
lias the same hue as the tooth in that location. In case this section of the
tooth shows a hue of gray or brown, a thin layer of enamel of the re-
quired hue is applied and fired to a high biscuit before the enamel of the
predominating hue is applied. The middle third is then covered with
the enamel of the desired hue and hard biscuited. The incisal third is
built with an enamel that approaches the hue of the incisal third of the
natural tooth and fired to a hard biscuit, after which a uniform layer of a
neutral color is applied and fused.
There are conditions, however, under which it is
mixing Colors. deemed advisable to mix colors in the construction
of inlaws. While this is not necessary in the greater
number of cases, the author has found that the mixing of colors some-
times yielded better results than he could secure by other methods of
application. Some colors may require modification. The yellows, for
example, may need to be toned with the grays ; the grays brightened by
the addition of yellow ; or the blues may be lightened by the admixture
of green, or saddened by the addition of a gray.
In mixing two porcelains or in applying them in layers, it must be
borne in mind that the resulting color is primarily due to the power of
the combined porcelains to absorb or transmit light. When the two por-
celains are mixed, or when they are applied in thin layers, the resultant
color is that which is transmitted by both colors in common. When two
colors, as blue and yellow, are combined, it is found that green is the only
color that is common to both of them, and this is, therefore, freely
transmitted or reflected; the others being absorbed. If a layer of blue is
placed over a layer of yellow, the light, in passing through the blue por-
celain, loses its red, orange, and yellow rays, which are absorbed, and are
not, therefore, transmitted ; while green, blue and violet are transmitted
to the yellow, which absorbs the blue and the violet, leaving the green
to be transmitted or reflected. The purity of the green is dependent upon
the purity of the yellow and the blue, and by the thickness of the layers.
\Mien blue is used to build the incisal portion of an inlay, the yellow
foundation should extend only to the point at which the blue is to begin
for the blue will have a greenish hue, if it is applied over the yellow.
When yellows and blues are applied over grays or browns, the underlying
colors have the quality of saddening the overlying ones, because the trans-
mitted rays from the yellow and blue are largely absorbed by the gray
or brown.
91
