The easiest way to identify an antique stoneware crock is through its salt-glazed finish, which is light colored with a grey tinge, rough and pebbled. Crocks that have the same salt glazing on the inside predate 1800, according to information from the Museums of West Virginia. Newer vessels are likely to be coated inside with a brown finish known as Albany slip. Antique stoneware crocks have marks and symbols that collectors can use to trace the origins. From geometric shapes to symbols from nature, these marks are as varied as the pieces they identify. Words or initials are also common forms of stoneware identification.
Stoneware pottery from the 1700s that hails from Europe may bear the symbol of an anchor. Very old pieces have crude designs with few lines and very little detail. Nineteenth-century anchor designs are more elaborate and intricate. German and Old English pottery may exhibit a crown or a shield as its manufacturing mark. If the piece was made after 1891, it also bears the country of origin. Pieces manufactured after 1914 include the words "Made in" along with the country of origin.
Human body parts or mythical creatures are often indicative of pottery made in the 19th or 20th century. Hands and arms are most common, often clutching swords or arrows. Company names usually accompany these unique marks, making it easier for the collector to date the individual piece.
Pottery or stoneware marked with foreign alphabets are difficult to trace. The intrigue is often sufficient motivation to try, however, as pieces bearing these marks are frequently ancient and very rare. Some pottery marked with foreign alphabets can be dated back to 13th-century China.
Prior to the Revolutionary War, the U.S. Colonies imported all their stoneware from Europe. In the decades following the war, Americans established stoneware factories in New York, Pennsylvania and New Jersey. The designs on each piece of stoneware provide clues to its origin and age, according to antiques appraiser Dr. Lori. These can be decorative symbols or figures, often rendered with cobalt blue glaze.
Makers also stamped their crocks with their names or locations. For example, a crock bearing the stamp "Manhattan Wells" identifies its origins as Clarkson Crolius factory in New York, explains a Collector's Weekly article. A less common but just as collectible stoneware crock bearing a cobalt blue, hand-painted design might bear the mark "Adam Claire, Po'keepsie," which indicates the piece dates to the late19th century.
Dr. Lori points out that a more artistically rendered design on a stoneware crock is likely to raise the value of the vessel. Value also depends on age, condition and rarity of a piece of stoneware, so learning to identify such factors is essential to becoming a successful collector.