Porcelain test piece

In 1672, John Dwight set up a pottery in Fulham. He became the first Englishman to make stoneware, produced by firing clay at very high temperatures. He copied ‘Cologne ware’, a German stoneware that was imported into England. In 1676, the Glass Sellers’ Company agreed to buy the whole of his stoneware production for three years. In the 1970s, excavations at Fulham revealed the extent of Dwight’s wares and experiments.

Chinese porcelain was in great demand in Europe but no one knew how to make it. John Dwight tested different ceramic bodies and glazes trying to find the secret but in the end failed. Some of the test pieces are marked with Greek letters and code numbers. This test chip has cobalt painted marks and numbers to identify the trial. This chip has been partly dipped in a slip to which the blue decoration is confined and this largely masks the fabric. The painted marks, a '71' with dashes, were evidently a form of code adopted by Dwight to maintain the secrecy of his operation. The use of waste sherds and small identifiable strips of clay to test the effect of varied glaze and slip compositions is one of Dwight's most remarkable innovations, indicating his use of controlled, repeatable experiments.