What is “Wet Piling” (Wo Dui)?

What is “Wet Piling” (Wo Dui)?

Traditional pu erh tea can take years to age, but this changed when the ‘wet piling’ or ‘wet storage’ method was discovered.

Wet piling, in China known as ‘wo dui’ (渥堆) is a fermentation process used for the production of ripe pu erh. This technique manipulates conditions to accelerate the pu erh aging process by prolonged bacterial and fungal fermentation in a warm humid environment under controlled conditions.

Sheng & Shou Pu Erh

The wet storage process was first developed in 1972 by Menghai Tea Factory and Kunming Tea Factory to imitate the flavour and colour of aged pu-erh. Because of this brilliant invention, the long fermentation period of the traditional ripe Pu erh is shortened to about 45 days.

The intention was to imitate the natural aging of raw (sheng) pu erh tea. However, due to the significant different taste profile, a new style of pu erh was created and referred to as ‘shou’ or ‘shu’ pu erh.

Both sheng en shou pu erh start with

How Does Wet Piling Work?

wo dui wet storage pu erh tea

To apply the wet piling method, one first needs ‘mao cha’ which literally is ‘unfinished tea’. This mao cha is the result of picking, pan firing, rolling and sun-drying leaves. Mao cha is then compressed into sheng pu erh cakes, or wet stored to create shou pu erh. We discuss the wet storage steps below.

The process of wet piling involves piling, wetting, and turning the tea leaves which is similar to composting:

  • Piling: pile the mao cha leaves to certain height. This usually around 70 cm, but individual tea masters have their own preferences.
  • Wetting/dampening: wet the piles of mao cha with water, and cover them with a linen cloth. This step allows the mao cha to stay in a warm and humid environment in order to accelerate the fermentation.
  • Turning: wait until the piles of tea ferment to certain degree, spread them out and air.

Depending on the different degrees of wet piling, mao cha can turn from green to yellow, maroon, or brownish black colour. You can tell the wet piling degree from the colour of the liquor – the darker the liquor gets, the higher the wet piling degree is, and vice versa.

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