Byzantine mosaics are found in the upper parts of churches. Lower parts were covered with dado (marble slabs). Mosaics require long and tiring and thus patient work. Tesserae were cut from various types of coloured stone and teracotta, while the generalised use of glass allowed for vivid colour combinations. Gold and silver tesserae, made of sheets covered with glue and glass, the most expensive material.
The preparation of the wall entailed a first insulation layer of resin. Nails with wide heads were frequently hammered
in the wall in order to hold the plaster layers that followed. There were three layers, one coarse and hydraulic, and
two finer layers. The last layer accepted the tesserae according to a sketch that the artist had already drawn
on the wall. Tesserae were put in different angles, in order to achieve an increased glittering effect. Details, such
as human heads, were first worked on linen sheets and then placed on the wall as a whole. Contrary to Greek and Roman mosaics, there was no final polishing of the surface, because this increased light glittering. Akra Tapeinosis (Man of Sorrows); wall painting dating from the 16th century in the Prothesis conch of the small Agios Georgios church (photo by Sp. Panagiotopoulos).