Flow blue was a type of transfer pottery produced by Staffordshire, England, potters beginning in about 1820. Sold mostly in the U.S. market, flow blue was similar to traditional blue-and-white pottery, except that the blue color was deliberately blurred, an effect achieved by adding a cup of lime or ammonia to the kiln during glazing. English manufacturers of antique flow blue included Wedgwood, Johnson Brothers, Minton, Royal Doulton,...Continue Reading