Islam brought important developments in manufacture and trade to the towns of The Middle East. Two techniques were developed in the 19th century: in one the white surface was produced by Led glaze made opaque and white by the addition of small amounts of tin oxide or other opacifier, and in the other a white slip covered the coloured Earthenware body under a clear lead glaze.
The distinctive lustre effect which is particularly associated with Islamic pottery from the 9th to the 14th centuries was developed from a technique probably borrowed from the decoration of glass. After firing the ochre would be rubbed off to reveal the design in a variety of metallic colours from Gold to red and brown depending on the relative proportions of the metal oxides used. The paint was easy to apply to the glazed surface and fine and intricate designs were achieved.
The ancient technique of applying a thin layer of white clay as a liquid slip to the still wet earthenware body of a pot was later developed further, particularly in Iran. Designs were painted in slips of different colours - usually black, brown or red - on the white foundation and covered with a clear glaze fluxed with lead oxide. Designs were also incised or carved through the white slip to allow the coloured clay of the body to show through.
In Ancient Mesopotamia, as in ancient Egypt, simple geometry was used in measurement of land, in construction of buildings and in astronomical calculations.
Geometry became highly important in the Islamic world as its figures and constructions were permeated with symbolic, cosmological and philosophical significance.
In architecture strict adherence to geometric principles in plans and elevations was the basis of the Harmony and discipline which characterise all Islamic art. In decoration geometrically based designs covered entire surfaces, typically with a geometrical framework leaving spaces to be filled with interlaced and stylised Leaf and Floral Designs.
Geometrical designs are basically very simple: they may be constructed with only a compass and Rule and the knowledge of certain procedures which produce triangles, squares, hexagon, stars, etc. Their designs may be reduced and enlarged with great ease. By repeating these procedures, and 3 further divisions and the addition of straight and curved lines, almost limitless elaborate variations may be achieved.
