English potters attempted to emulate the fine blues and bright whites of authentic Chinese porcelain with different clay and glaze formulations. Cobalt oxide provided the deep blues that were sought after, and in the mid-18th century, transfer printing of designs allowed higher production than traditional hand painting of designs on pottery. Yet transfer printing produced seams and flaws that were obvious and artificial.
The flow blue glazing technique is believed to have been invented or possibly accidentally discovered by Josiah Wedgewood II in Staffordshire, England. Flowing blue over print transfer designs hid flaws in the printing, molding and glazing processes. Flow blue is achieved by flooding the hot kiln with volatile chloride gases.
The flow blue process was difficult to regulate, and some pieces were considerably more flowed than others. English potters found a market for these "seconds" in America, where flow blue pottery became exceptionally popular. Demand was so great that English potters began to produce first-quality flow blue for the market, and the "golden age" of flow blue pottery, with the highest quality pieces produced, continued from the 1870s until the beginning of the twentieth century.
Flow blue ware has a mysterious hazy, romantic quality that is reminiscent of the ancient Orient. Originally developed to hide flaws in lesser quality porcelains, flow blue developed into a stand-alone technique with exceptional popularity. Its popularity waned with the introduction of cheaper porcelains in the early twentieth century. As antiques, flow blue pottery started to gain popularity in the 1960s and is in high demand to this day.
Early flow blue pottery emulated Oriental porcelains depicting distant landscapes, floral motifs and other exotic themes. Later flow blue pottery is dominated by Victorian and Art Nouveau patterns. Different colors, including greens and browns, were introduced in the later stages of "flow blue's" popularity.