The decline of the Iznik pottery industry in the C17th is closely linked with the slow decay of Ottoman empire itself: potters need patrons, but at the time the Sultans were more concerned with management than with monuments. The most popularly quoted source on the decline of Iznik is the Turkish traveller, Evliya Çelebi, who visited the town in 1648 and noted that there were only 9 workshops left compared to more than 300 during the industry’s peak, barely 50 years before. While this is probably an exaggerated estimate, it is indeed the case that Iznik was running downhill during the reign of Ahmed I (1603-17), shown in the general technical decline of quality and design in much C17th pottery from Iznik.

The situation is perhaps not as simple as the withdrawal of patronage: a number of firmans (official court directives) were issued during Ahmed I’s reign, reminding the potters of their primary obligation to keep a supply of tiles to the capital, for the Sultan Ahmed, or ‘Blue’ (after the predominant colour of the tiles), mosque which was completed in 1617, having taken a decade to complete. Vast quantities of marble and other materials were used (the Venetians provided the coloured glass for the windows), and a massive labour force was employed, all documented in the largely unexplored Ottoman archives. Ahmed I had an obsession with tiles, and commanded over 20,000 from Iznik; extra clay had to be imported from Kütahya, and the tilemakers were forbidden to work for anyone else in the meantime. The tiles themselves vary considerably in quality, though some are finely painted.

The completion of the Sultan Ahmed mosque marks the end of Iznik as a major supplier of tiles to the court: the Yeni Valide mosque, constructed on the south side of the Golden Horn in 1663, uses Iznik tiles sparingly; re-used earlier tiles were used for Sultan’s loge, while the tiles on the exterior are definitely of inferior quality to their predecessors. When the Sünnet Odasi at the Topkapi Saray was enlarged in 1641/2, the general dearth of tiles meant that extra tile panels were reused from elsewhere.

Blue and turquoise began to predominate again, and patterns tended to be confined to single tiles, rather than part of an elaborate decorative scheme. Characteristic of this period are single tiles with a symmetrical spray of carnations and other flowers in a vase.

The potters turned elsewhere because there were not enough orders coming from the Ottoman court, and by the midC17th large quantities of tiles were exported to Egypt: the mosque of Ibrahim Agha in Cairo was restored in 1652, and is filled with blue and turquoise tiles; there are also similar tiles in the Coptic Church of Deir Abu Seifein, also in Cairo.

Though blue and turquoise were again predominating in Iznik, the potters did not entirely lose the ability to work in a fuller range of colours, since the tiles that were specially commissioned to decorate the iconostasis of the main church on Lavra, Mount Athos (dated to 1678 by its Greek inscriptions) contain besides cobalt blue and turquoise a dingy green and relief red, which is surprisingly bright for such a late period.

These last few examples show that in the C17th the Iznik potters were not averse to working for non-Muslim patrons if the commission (and thus the price) was right; though we may think back to the Armenian-commissioned Kütahya examples of the early C16th. A number of Iznik dishes have Greek inscriptions on the rim and a variety of dates (which include 1640, 1646, 1666, 1667 and 1678), while two in the British Museum have interesting decorations: on the first is a two-storey pagoda-like kiosk with open galleries and ladders leading to the first and second floors; hanging ornaments suggest a religious structure, and Carswell suggests it is perhaps a stylisation of a skite, or humble monastic dwelling on Athos, leading one to wonder if the plate’s decorator actually saw the building, or did its commissioner draw him a picture? An inscription reads: "O Lord, Lord, avert not thy countenance from us May 25 year 1666". (Khrie Khrie mh apostrefis to prosopon sou af imon maiw 25 etos 1666)

The second Greek-Iznik plate in the British Museum is dated 19 June 1667, and is painted with a plump hand whose thumb touches the second finger in a sign of blessing; this is surrounded by tulips, and its inscription reads: "O Lord, protect our Lord & Archpriest June 19 1667".

(Ton despothn ke archereaimon kirhe fulate hounio 19 1667)

Another undated dish in the Ashmolean has a more precisely Christian theme, showing the façade of a church with 3 onion-shaped domes surmounted by crosses; its inscription reads: "the pride of Nicaea, the splendour of the inhabited world, years…"

(Nhkeas to kauchma hkoumenis aglahsma eth...), thus giving its provenance as Iznik (which was the ancient city of Nicaea). A tile with a cross and Greek inscription in the Topkapi Saray is decorated with an arched panel, probably once part of a sebil or wall-fountain; decorated in blue and turquoise, it is dated 1667.

Another dish in the Benaki Museum is dated 25 May 1666 (exactly the same date as the first British Museum dish, above), depicting a wolf and boar’s head, and reads: "O Christ our God, have mercy on the homeless May 25 year 1666".

(Ahkeoshnis hlienohte crhste o qeos hmon maiw 25 etos 1666)

Other dishes have as their subjects birds, a pack-horse, a lion attacking an ox, human figures (unusual for Iznik) including a pair of acrobats walking a trapeze, Turkish ladies and gentlemen, a European fop, a Turkish soldier leading a captive by a rope, a mustachioed Turk with a plumed turban sitting on flowery bank. However, the commonest motif is the sailing-ship, of various designs. This is perhaps a clue to one of the most important new markets for Iznik dishes in the C17th, ie. the purchase by Greek sailors at Çanakkale on the Dardanelles or in Istanbul itself; the walls of many houses in Lindos on Rhodes are plated with crockery of this type, which had led to the early C20th fallacy that these Iznik wares were made on Rhodes.

Another characteristic of C17th Iznik ware was the use of supplementary gold-leaf decoration to liven up the dull colours; though this had been an Ottoman tradition as early as the Yeshil Cami in Bursa. And another C17th departure was the production of tiles painted with stylised views of Mecca and Medina, and their holy shrines: the Ka’ba, for example, is a favourite subject. These are similar in style to manuscript illuminations which served as points of reference for prospective pilgrims of the hajj.

The C17th is thus a time when the potters of Iznik show an increasing awareness of the possibilities of decorating ceramics in new ways, and are less concerned with the dictates of court style, and more with the everyday life of their new clients. However, none of these novelties are enough to sustain the industry at Iznik, and by the end of the C17th it was close to collapse. This period also saw the emergence of rivals, for example at Diyarbakir, where a separate tile manufacturing industry began in the late C16th, which was possibly inspired by itinerant craftsmen from Iznik. Its products have a distinctive but technically inferior style which seems only to have been used in the mosques and churches of Eastern Anatolia.