The use of glazing begins far back in the prehistoric age, some thousands of years before any examples of glass are known. Glaze is found on a quartz base as early as on a pottery base; and it seems probable that it was invented from finding quartz pebbles fluxed by wood ashes in a hot fire. Hence glazing on quartz was the starting-point, and glazing on artificial wares was a later stage. Amulets of quartz rock are found covered with a coat of blue-green glaze; a model boat was made of quartz rock in sections, glazed over, and united by gold bands; and a large sphinx of quartz, about eighteen inches long, has evidently been glazed. The fusion of glaze on the stone partly dissolves the surface; and even after the glaze has been lost its effect can be seen by the surface having the appearance of water-worn marble or sugar candy. This system of glazing on quartz was continued in historic times; clear crystal beads flashed over with a rich blue glaze are found in the XIIth dynasty; and large blocks were glazed in the XVIIIth dynasty.
The use of a pottery ware for covering with glaze begins with beads of blue and green in the prehistoric necklaces. The pottery base for glazing is never a clay in Egypt, but always a porous body of finely-ground silica, either sand or quartz rock. This was slightly bound together, but the whole strength of the object was in the soaking of glaze on the outer surface.
An astonishing development of glazed ware came at the beginning of the monarchy. A piece of a vase (fig. 116) with the name of Mena, the first king of Egypt, is of green glazed pottery, and it is surprising to find the royal name inlaid in a second coloured glaze, which has probably been violet, though now decomposed. Thus two-colour glazing in designs was used as early as 5500 b.c. And at this date glazing was not only a fine art, it was used on a large scale for the lining of rooms. Tiles have been found about a foot long, stoutly made, with dovetails on the back, and holes through them edgeways in order to tie them back to the wall with copper wire. They are glazed all over with hard blue-green glaze. The front is ribbed in imitation of reedwork, and they probably were copied from reed mats used to line the walls. Part of a tile has large hieroglyphs inlaid in colour, showing that decorative inscriptions were set up. Rather later, at the beginning of the IIIrd dynasty, there is the doorway of glazed tiles of King Zeser, with his name and titles in various colours; this doorway, now in Berlin, belonged to a room in the Step pyramid entirely lined with glazed tile.
116. Two-colour glaze of Mena.
117. Lotus border (XXth dynasty)
118. Head of Isis.
119. Royal fan-bearer.
Smaller objects were also made in glaze. A tablet of the first dynasty bears a relief of the figure and titles of an aboriginal chief, apparently made to be left as a memorial of his visit to temples - a sort of visiting card, - as it was found in the temple of Abydos. Figures of women and animals were found with it, and glazed toggles to be used in place of buttons on garments. Very little glazing has been preserved to us from the pyramid age; there are small tablets with the name of King Pepy (4100 B.C.) in relief, but roughly done.
The general colour of the early glaze is greenish-blue or blue-green, never distinctly of either colour. Such appears from the prehistoric age to the pyramid time. The glaze is full, and was not heated long enough to soak into the body. It often has pit-holes in it, and does not seem to have been very fluid. In the VIth dynasty a second colour appears, a dark indigo blue; this is on a scarab of Merenra, and on small toilet vases of the period. Some earlier scarabs are probably of the age of the IVth, and even of the IIIrd dynasty; these have a clear brilliant blue glaze, thin and well fused.
In the XIIth dynasty the glaze is thin and hard. On ring-stands and vases it is often dry and of a greyish green. A rich clear blue glaze was also used, and is best seen on scarabs and on the favourite figures of hippopotami, which were only made in this period. The designs and inscriptions in the glaze were of a fine black, apparently coloured with manganese.
The XVIIIth dynasty was the great age of the development of glazing. It began with so close a continuance of the style of the XIIth dynasty that it is hard to discriminate one from the other. Down to the time of Tahutmes III the small pieces and beads with blue colour are as those of the previous age; but the large bowls are of a brighter blue and rather a wetter glaze. At the beginning of the dynasty there is also a dark green glaze used upon schist, mostly seen on the elaborately carved kohl pots. Under Amenhotep II was made the largest piece of glazing that is known from Egypt, now in South Kensington Museum. This was a great uas sceptre made as an offering, the stem of which is five feet long. This length was built up of separate sections of body ware, made each about nine inches long, so as to have sufficient firmness; after they were each baked they were then united with a slip paste of the same ware, and finally fired with a single flow of glaze over the whole five-feet length. The head was made separately. The special difficulty of firing such large pieces is to maintain a uniform heat over the whole, and to avoid any reducing flame from the fuel, which would discolour the glaze, and produce lustre ware. The heating must also be brief, so as to avoid the glaze running down, or soaking into the porous body and leaving it dry.