d decoration by the later Egyptian, Syrian and Persian potters.
Green, yellow and brown glazes were almost the only artistic
productions of the medieval European potters' kilns, and their use
everywhere preceded the introduction of painted pottery. The most
extensive application of coloured glazes was, however, that made by
the Chinese, who developed this type of colour decoration before they
used painted patterns in underglaze colour. The earliest Chinese
porcelains, and the hard-fired stonewares out of which their porcelain
arose, were decorated in this way, and the beauty of many of the early
Sung coloured glazes has never been surpassed.

With the exceedingly refractory felspathic glazes of Chinese porcelain
very few underglaze colours could be used; and the prevalence of blue
and white among the early specimens of Chinese porcelains is due to
the fact that cobalt was almost the only substance known to the
potters of the Ming dynasty which would endure the high temperature
needed to melt their glazes. Consequently the Chinese were driven to
invent the method of painting in coloured fusible glasses on the
already fired glaze. They adopted for this purpose the coloured
enamels used on metal; hence the common term "enamel decoration,"
which is so generally applied to painting in those colours which are
attached to the already fired glaze by refiring at a lower
temperature. With the introduction of this many-coloured Chinese
porcelain into Europe the same practice was eagerly followed by our
European potters, and a new palette of colours and fresh styles of
decoration soon arose amongst us. Painting in on-glaze colours, being
executed on the fired glaze, resembles glass painting, and it
generally offers a striking contrast both in technique and
colour-quality to the painting executed in colours under the glaze. In
the former the work can be highly finished and the most mechanical
execution is possible, but the colours are neither so rich nor so
brilliant as under-glaze colours, nor have they the same softness as
is given by the slight spread of the under-glaze colour when the glaze
is melted over it.

It must be pointed out that the colour possibilities in any method of
pottery decoration are largely dependent on the temperature at which
the colour needs to be fired. The clay colours are naturally more
limited in range than the under-glaze colours,