Drying After Pressing: Air-Drying, Drying Rooms, and Temperature

When a cake has just been pressed and the cloth bag comes off, it feels warm and soft, because the steaming has filled it with moisture. At this point it can't be wrapped yet. First it needs to dry.

How Cakes Are Dried After Pressing

A freshly pressed cake holds noticeably more moisture than sun-dried maocha. There are three common drying methods:

Natural Air-Drying

Cakes are stood up one by one on wooden or bamboo racks with space between them, and left to dry slowly in the shade in a clean, well-ventilated room. Air-drying takes several days, longer in the rainy season, depending on the weather and how tightly the cakes are pressed. It's the most traditional method, the temperature is gentle, and tea drinkers generally feel it preserves aroma best.

Drying Rooms

Cakes are placed in a room fitted with heating and ventilation, where low temperatures steadily draw out moisture. It's faster than air-drying and doesn't depend on the weather, so factories use it often, especially in the rainy season.

Sun-Drying

A few farmers put cakes out in the sun, but sun temperature is hard to control: the surface dries quickly while the center dries slowly. It's rarely used for large-scale production.

What Temperature for the Drying Room?

Yunnan's technical processing guidelines for pu'er recommend drying compressed tea at no more than 60°C. In practice, many factories dry slowly at temperatures below that limit, preferring to take a few more days.

Why low heat? Research comparing ripe pu'er dried at different temperatures found that air-drying and low-temperature drying below 60°C preserved the tea's constituents and sensory quality better; the higher the temperature, the more the aroma and taste tended to suffer. For raw tea, low-temperature drying is also thought to better preserve its potential to change with age.

How Dry Is Dry Enough?

Under the national standard for pu'er, finished tea has moisture limits:

Factories test samples for moisture and only move cakes to wrapping once they're thoroughly dry. Experienced makers also tap and sniff: a fully dry cake sounds crisp when tapped, and its center has no damp, stuffy smell.

What Happens If It Isn't Dry Enough

• Stuffy center: the outside is dry but the center is still damp; once wrapped, the moisture can't escape, and the center develops sour, stuffy odors.
• Mold: high moisture in a warm environment invites mold, with white, green, or black spots on the surface or in the center.
• Aging goes astray: changes happen too quickly in storage, and the aroma becomes muddy.

So if you bring a new tea home and smell an obvious damp, stuffy odor when you open it, unwrap it and leave it somewhere clean and well ventilated for a few days to see how it does.

How High-Heat Drying Affects Tea

• Aroma: it brings out a "fire" or roasted note. The new tea smells fragrant but lacks the freshness of sun-dried tea.
• Taste: the mouthfeel is dry and parched; some people describe it as having "fire" (huoqi).
• Aging: tea drinkers generally feel that raw tea dried at high heat changes less interestingly in storage.

It's the same principle as the difference between sun-dried (shaiqing) and oven-dried (hongqing) maocha. See Sun-Dried, Oven-Dried, Pan-Fired: Why Pu'er Has to Be Sun-Dried.

After Drying

Fully dried cakes are wrapped in cotton paper, stacked seven to a tong in bamboo-sheath wrappers, and then boxed or packed in bamboo baskets. See Traditional Wrapping: Cotton Paper, Bamboo Sheaths, Bamboo Baskets. The full pressing process is covered in Pressing Pu'er: Steaming, Stone Molds, Machine Presses, and Compression.

Space and Layout for Drying

Whether air-drying or using a drying room, how the cakes are arranged matters:

• Upright or on racks: cakes stand on edge or lie on perforated racks so both sides can breathe.
• Spacing: space is left between cakes so air can circulate.
• Regular turning: cakes lying flat are turned so both sides dry at the same rate.
• A clean environment: drying rooms must be free of cooking fumes, spices, chemicals, and other odors. Cakes absorb smells especially easily at this stage.

Managing a drying space follows the same principles as storing tea at home later on: clean, ventilated, and odor-free.

The "Water Note" in New Tea

Even when a recently pressed tea has been dried within the standard, tea drinkers often say it still carries a bit of "water note" (shuiqi): the aroma is a little stuffy and the liquor isn't quite crisp. That's because after steaming and pressing, the moisture and aromas inside are still rebalancing. Left somewhere clean and ventilated for a few weeks to a few months, the water note fades and the aroma becomes clearer. So if a new tea seems a bit stuffy when you bring it home, give it some time before brewing.

FAQ

How are cakes dried after pressing? Air-dried naturally or dried in a drying room at low temperature, and wrapped only once fully dry.

What temperature should a drying room be? Yunnan's processing guidelines recommend no more than 60°C for compressed tea, and many factories dry more slowly at lower temperatures.

What happens if it isn't dried enough? The center of the cake tends to develop sour, stuffy odors, and in serious cases mold.

How can you recognize tea dried at high heat? New tea has a fire-roasted aroma and a parched mouthfeel, and tea drinkers generally feel it changes less interestingly in storage.