Iznik pottery, but analysis of the surviving pieces indicates that the potters in İznik used roughly similar proportions. In Kashan the frit was prepared by mixing powdered quartz with soda which acted as a flux. The mixture was then heated in a kiln. In İznik, as well as quartz and soda, lead oxide was added to the frit. As the fritware paste lacked plasticity and was difficult to work on the wheel, vessels were seldom made in one piece. Instead they were formed in separate sections that were allowed to dry and then stuck together using the fritware paste. This additive technique meant that there was a tendency for the final vessels to have slightly angular shapes. Dishes were almost certainly made using a mould attached to a potter's wheel. A lump of fritware paste would have been rolled out into a sheet much like when a cook rolls out pastry. The sheet would have been placed on the mould to form the inside of the dish. The underside of the dish would have been shaped using a template as the mould was rotated on the wheel. When the paste was partly dry the foliate rim would have been sculptured by hand. The fritware body was coated with a thin layer of white slip. This had a similar composition to the fritware paste used for the body, but the components were more finely ground and more carefully selected to avoid iron impurities that would discolour the white surface. It is likely that an organic binder was also added such as tragacanth gum. Although in his treatise Abū'l-Qāsim recommended that fritware vessels were allowed to dry in the sun before being decorated, it is probable that Iznik ceramics was given a biscuit firing. The pottery was painted with pigments that had been mixed with glass frit and ground in a wet quern. For some designs the outlines were pounced through a stencil. In the early period only cobalt blue was used for decoration. The cobalt ore was probably obtained from the village of Qamsar near the town of Kashan in central Iran. Qamsar had long been an important source of cobalt and is mentioned by Abū'l-Qāsim Qamsarin in his treatise. From around 1520 turquoise (copper oxide) was added to the palette. This was followed by purple (manganese oxide), green, grey and black. The distinctive bright bole red was introduced in around