In this collection, "Ironstone" is used to denote a style of ceramic, not the technologically improved clay mixtures themselves. In the 1840s, there was a shift in popular British ceramics from colorful transfer printed and hand painted vessels to plain white vessels. These Ironstone vessels tended to be more durable because of their thicker walls. Some were decorated with molded relief designs. The Ironstone style appears to have dominated the middle-class market in the U.S. from the 1850s to the 1890s.