Liu Bao is a fermented tea similar in concept to Pu-erh, from Guangxi Province. The production method shares its earlier stages with Pu-erh, with the tea being picked and then allowed to oxidise a little by being laid out on a flat surface and left to dry and wither. This is very similar to Pu-erh in its 'maocha' or rough tea stage. Once the tea has reached the right level of oxidation, it is then put through the same sort of ‘killing the green’ or ‘sha qing’ process that is used in Pu-erh. This is usually either pan frying or steaming, with steaming being more common in Liu Bao production.
Once the oxidation process has been halted, the tea makers will hand roll the leaves into the desired shape and then put it through a second drying process so that they hold that shape from then on.
The key element of the Liu Bao process is the wet piling stage that follows. The leaves are piled up in humid conditions that promote the fermentation process, and left to ferment for some length of time. This varies, but is generally around two or three weeks. The wet piling process accelerates the initial fermentation, achieving in weeks what would take years if the leaves were left to ferment in dry conditions.
Depending on exactly which process is being followed, the leaves will be removed from the wet pile and steamed or dried again, before being stored before use. Liu Bao is generally left for at least another year in dry form for further aging to take place, and continues to mature continuously. Traditionally, the tea is stored in bamboo baskets allowing free movement of air, but Liu Bao sometimes appears in pressed cake form as is common with Pu-erhs.
Liu Bao originates in the late 18th Century, when the wet piling process was invented as a way to improve the results of processing local Guangxi province green tea. Inspiration from Pu-erh is possible, as fermented teas have been grown in Yunnan Province for much longer, but the exchange of ideas was a two way process. A similar wet piling process was developed in Yunnan during the 1970s to artificially age certain Pu-erhs, using similar processes but giving very different results because of the cultivar and the differences imparted by climate and soil.