During the classical period, the under glazing technique replaced previous techniques and proved to be a success. The design, colour and quality of the wares produced were superior to those before and after.
Once the clay had been moulded, the piece would be fired.
After it cooled, to put the design on it, a pattern would be drawn on paper and then holes made with pins. This pattern would be put on the tile or ceramic piece and charcoal dust scattered over it. The pattern would be removed and painted, keeping to the outline left by the charcoal dust.
Then a transparent glaze would be applied to the item, and it would be fired again. This was called under glazing and was a relatively easy technique which led to stylistic changes in the motifs used. A more naturalistic style was used as the colour palette increased. The Seljuks in Anatolia had favoured turquoise, dark purple, blue, and black but now under the Ottomans, green, red and light purple were added to the repertoire.
The most important of the changes was the addition of a particular red colour that is either described as coral or tomato red or just Iznik red. This begins to appear in the middle of the sixteenth century and is first used alongside the popular blue, white, turquoise, and black in the interior decorations for Süleymaniye Mosque in Istanbul from 1550 and 1557.
The coral red was a discovery of the Iznik tile workshops.
Today we are fortunate in that there are many examples of red Iznik tiles and ceramics in Turkiye.