Compressed tea

Porters laden with "brick tea" in a 1908 photo by Ernest Henry "Chinese" Wilson, an explorer botanist

In ancient China, compressed teas were usually made with thoroughly dried and ground tea leaves that were pressed into various bricks or other shapes, although partially dried and whole leaves were also used. Some tea bricks were also mixed with binding agents such as flour, blood, or manure to better preserve their form so they could withstand physical use as currency.[1] Newly formed tea bricks were then left to cure, dry, and age prior to being sold or traded. Tea bricks were preferred in trade prior to the 19th century in Asia since they were more compact than loose leaf tea and were also less susceptible to physical damage incurred through transportation over land by caravans on the Ancient tea route.

Tea bricks are still currently manufactured for drinking, as in pu-erh teas, as well as for souvenirs and novelty items, though most compressed teas produced in modern times are usually made from whole leaves. The compressed tea can take various traditional forms, many of them still being produced. A dome-shaped nugget of 100g (standard size) is simply called tuóchá (沱茶), which is translated several ways, sometimes as "bird's nest tea" or "bowl tea". A small dome-shaped nugget with a dimple underneath just enough to make one pot or cup of tea is called a xiǎo tuóchá (小沱茶; the first word meaning "small") which usually weighs 3g–5g. A larger piece around 357g, which may be a disc with a dimple, is called bǐngchá (饼茶, literally "biscuit tea" or "cake tea"). A large, flat, square brick is called fāngchá (方茶, literally "square tea").

To produce a tea brick, ground or whole tea is first steamed, then placed into one of a number of types of press and compressed into a solid form. Such presses may leave an intended imprint on the tea, such as an artistic design or simply the pattern of the cloth with which the tea was pressed. Many powdered tea bricks are moistened with rice water in pressing to assure that the tea powder sticks together. The pressed blocks of tea are then left to dry in storage until a suitable degree of moisture has evaporated.

Although the Chinese regard it as an inferior product, [tea bricks are] greatly esteemed by the Tibetans for [their] powerful flavor, which harmonizes particularly well with that of the rancid yak's butter which they mix with their tea. Brick tea comprises not only what we call tea leaves, but also the coarser leaves and some of the twigs of the shrub, as well as the leaves and fruit of other plants and trees (the alder, for instance). This amalgam is steamed, weighed, and compressed into hard bricks, which are packed up in coarse matting in subunits of four. These rectangular parcels weigh between twenty-two and twenty-six pounds—the quality of the tea makes a slight difference to the weight—and are carried to Kangting by coolies.[2]

The brick tea is packaged [in Kangting] either in the courtyard or in the street outside, and it is quite a complicated process. When the coolies bring it in from Ya'an, it has to be repacked before being consigned upcountry, for in a coolie's load the standard subunit is four bricks lashed together, and these would be the wrong shape for animal transport. So they are first cut in two, then put together in lots of three, leaving what they call a gam, which is half a yak's load. Tea which is going to be consumed reasonably soon is done up in a loose case of matting, but the gams, which are bound for remote destinations, perhaps even for Lhasa, are sewn up in yakhides.[3]

A brick of Hubei mǐ zhūan chá (米磚茶), made of powdered black tea

Due to their density and toughness tea bricks were consumed after they were broken into small pieces and boiled. Traditionally in Tang Dynasty, they were consumed after having been ground to a fine powder. The legacy of using tea bricks in powdered form can be seen through modern Japanese tea powders as well as the pulverized tea leaves used in the lei cha (擂茶) eaten by the Hakka people and some people in Hunan province.

A brick of tea presented to Tsar Nicholas II, 1891

Due to the high value of tea in many parts of Asia, tea bricks were used as a form of currency throughout China, Tibet, Mongolia, and Central Asia. This is quite similar to the use of salt bricks as currency in parts of Africa. Tea bricks were in fact the preferred form of currency over metallic coins for the nomads of Mongolia and Siberia. The tea could not only be used as money and eaten as food in times of hunger but also brewed as allegedly beneficial medicine for treating coughs and colds. Until World War II, tea bricks were still used as a form of edible currency in Siberia.[1]

Tea bricks for Tibet were mainly produced in the area of Ya'an (formerly Yachou-fu) in Sichuan province. The bricks were produced in five different qualities and valued accordingly. The kind of brick which was most commonly used as currency in the late 19th and early 20th century was that of the third quality which the Tibetans called "brgyad pa" ("eighth"), because at one time it was worth eight Tibetan tangkas (standard silver coin of Tibet which weighs about 5.4 grams) in Lhasa. Bricks of this standard were also exported by Tibet to Bhutan and Ladakh.[11]

All tea plant tissues accumulate fluorine to some extent. Tea bricks that are made from old tea leaves and stems can accumulate large amounts of this element, which can make them unsafe for consumption in large quantities or over prolonged periods. Use of such teas has led to fluorosis, a form of fluoride poisoning that affects the bones and teeth, in areas of high brick tea consumption such as Tibet.[12]

• Tea Money of China. Ken Bressett.