blistering or crazing. The colors attainable for under-glaze painting are much more limited in number than for china painting. The reds are very poor, and pinks, purples, and some light colors, must be left for over glaze.
The colors change much more in the process of firing in under-glaze than in china painting. After having once been fired, additional touches may be given with the over-glaze colors, and in the hands of an expert very fine results are produced. Under-glaze is a favorite mode of decoration with those who are good colorists, as well as skillful handlers of the brush.
Some times biscuit is decorated with oil paints, being subjected to a slight firing which fixes the colors, but this decoration is, of course not so durable as when done with mineral colors.
I have seen a couple of little brown stone jars or bottles which had been, when bought, filled with French mustard, very prettily decorated with sprays of flowers, on a mottled background, painted in oil and then fired. They had very much the effect of under-glaze painting.
Special colors are sold for the different varieties of pottery or vitreous painting, as for over-glaze, underglaze, glass, terra cotta, etc., but the general principles for using them are the same in all cases.
