<P> In countries where the use of loose tea leaves is more prevalent, the term "tea bag" is commonly used to describe paper or foil packaging for loose leaves . They are usually square or rectangular envelopes with the brand name, flavour and decorative patterns printed on them . </P> <P> Packing tea in paper goes back to medieval 8th century China, during the Tang Dynasty when paper was folded and sewn into square bags to preserve tea flavoring and aromas . Then the paper tea bags were stitched from all sides to create protective casings for the tea leaves . </P> <P> The first modern tea bags in the Western World were hand - sewn fabric bags; tea bag patents date as early as 1903 . First appearing commercially around 1904, tea bags were successfully marketed about 1908 by the tea and coffee importer Thomas Sullivan from New York, who shipped his silk tea bags around the world . The loose tea was intended to be removed from the bags by customers, but they found it easier to brew the tea with the tea still enclosed in the porous bags . The first tea bag packing machine was invented 1929 by Adolf Rambold for the German company Teekanne . </P> <P> Modern tea bags are usually made of paper fiber . The heat - sealed paper fiber tea bag was patented in 1930 by William Hermanson, one of the founders of Technical Papers Corporation of Boston, who sold his patent to the Salada Tea Company . </P>

When did tea bags become popular in uk