This long sustained and exceedingly high temperature, necessary to incorporate the glaze with the body, intensifies some colors and diminishes the intensity of others, while, again, some colors, except under skill full treatment, will be entirely obliterated. But though the colors are few, and the risk is great, owing to the uncertainty of the action of fire, the possibilities of underglaze work are vast, in fact, illimitable.
Over glaze colors, which are more or less transparent, used to collectively designated as "enamel colors ; " but today, while their application is still a process of enamelling, the word enamel is used to indicate only those opaque colors that are applied in relief and in contradistinction to the transparent painting colors, which require rather different treatment.
Relief enamels and raise paste are both employed to produce effects that can by no other means be obtained.
The former is used to represent or enhance an apparent projection of the object painted, and when used intelligently and restrainedly is exceedingly attractive. It is also used for modeling flowers, figures, etc. ; and this is known as pate-Sur-pate. Raised past is only used as a basis for gold, and will be referred to in another chapter.
