The tea bag was an accidental commercial success. Thomas Sullivan, a New York tea importer, began sending samples of his tea in small silk pouches to customers. He intended for the customers to empty the loose tea into their pots, but they mistakenly dropped the entire silk bag into the boiling water. The convenience was immediate, and Sullivan soon began receiving orders for 'tea in bags.' He later replaced the expensive silk with gauze and then paper. The design of the tea bag has since evolved to include the 'flow-through' design and pyramid shapes to allow for better water circulation and leaf expansion. Today, 96% of tea in the UK is brewed using a tea bag, a major shift from the traditional loose-leaf methods that dominated for thousands of years.