What are some hallmarks of mastery? Historically, certain pottery such as storage jars required a structural thickness. However, for presentation or fine art pieces the thinness of a vessel’s wall is highly admired. The thinner, the finer. Nampeyo was an expert at the laborious process of pinching and scraping a coiled clay body. She did it so obsessively that in a number of her large flat-topped saucer-shaped jars (16 inches or more in diameter), the upper body is a mere quarter-inch thick. This is exceptional in that these pieces are pit-fired, hand-formed vessels.