Wok-Firing by Hand vs. Drum Kill-Green: How Shaqing Methods Differ

Kill-green (shaqing) is the most critical step for pu'er maocha: high heat deactivates the enzymes in the fresh leaves, stopping oxidation and driving off the green smell. There are roughly two tools for the job: a scorching-hot iron wok, or a constantly rotating drum machine.

Hand-Firing in an Iron Wok

The most common sight in the primary processing workshops of Yunnan's mountains is a row of large, tilted iron woks heated from below with wood, electricity, or gas, with a tea master firing the leaves by hand, bare-handed or gloved.

• Leaf load: A few kilograms of fresh leaves per wok, adjusted to the wok's size and the condition of the leaves.
• Technique: Alternating tossing, covering, shaking, and turning, so the thick large leaves heat evenly inside and out.
• Time: Mostly a dozen to twenty-some minutes per wok, depending on the tenderness and moisture of the leaves.
• Judgment: Watching the leaves turn from bright green to dark green, squeeze into a ball that doesn't spring apart, lose the green smell and give off a clean fragrance, and have stems that bend without snapping.

The advantage of hand-firing is that the master can feel the leaves changing at every moment and adjust heat and technique accordingly, which suits small, precious, variable batches of ancient-tree leaves. The drawback is that it's done one wok at a time, so it's inefficient, and quality depends on the master's condition.

Drum Kill-Green

A drum kill-green machine is a tilted, rotating metal cylinder heated along its body. Fresh leaves go in at one end, tumble forward as the drum turns, and come out the other end kill-greened.

• Large loads: Leaves can be fed continuously, processing far more fresh leaf per hour than hand-firing.
• Even and stable: Temperature, rotation speed, and feed rate can all be set, so batches differ little.
• Limitations: It's less flexible than human hands with leaves of varying tenderness and moisture; if temperature or speed is set wrong, the whole batch is affected.

Terrace tea and large-volume material mostly go through drums; many workshops also drum-fire first and then finish in the wok by hand, using the two together.

What Temperature Should the Wok Be?

The industry commonly says the hand-firing wok for sun-dried maocha is around 200°C, higher at the start and gradually lowered as the leaves lose moisture; drum temperatures are set in the same range and adjusted for the machine model and feed rate. These are experiential figures, with no universal answer; the key is "hot enough, fast enough, thorough enough."

The Yunnan Tea Circulation Association's 2021 group standard Sun-Dried Tea (Large-Leaf Variety) explicitly excludes "low-temperature, long-duration pan-firing for kill-green," because if the heat isn't high enough and firing goes on too long, the enzymes aren't stopped in time and the leaves slowly oxidize in the wok, producing red stems and a stuffy smell.

How Hand and Machine Kill-Green Differ

Neither is absolutely better. Many tea drinkers believe "handmade is always better," but a tired master firing his twentieth wok late at night isn't necessarily more consistent than a well-calibrated machine. More comparisons are in Handmade vs. Machine, Workshops vs. Factories.

Can You Taste Tea That Was Scorched?

Yes. If the wok is too hot or the leaves are tossed unevenly during kill-green, scorch spots and scorched edges appear on the leaf margins or surfaces, and after brewing you'll see:

• Dry leaf: Dark brown scorch spots on the strips.
• Aroma: A smoky, burnt smell, especially noticeable while hot.
• Infused leaves: Blackened edges and scorch holes.

A slight scorched note is sometimes mistaken for a "roasted aroma," but sun-dried pu'er shouldn't have an obvious burnt taste. After years of storage, the burnt taste fades but rarely disappears completely.

What Does Under-Fired Tea Taste Like?

If the kill-green temperature isn't high enough or the time is too short, the enzymes aren't fully deactivated, and the leaves keep oxidizing during the later rolling and sun-drying:

• The liquor tastes green and astringent, raw and grassy, or stuffy and sour;
• The infused leaves show red stems, red leaves, and red edges;
• Young tea sometimes tastes sweet and fragrant, but its later transformation is harder to predict.

These traces all remain in the infused leaves; pouring them onto a white plate after brewing is the most direct way to judge. The full kill-green and rolling process is in Kill-Green and Rolling: The Two Pairs of Hands That Shape a Pu'er; processing defects are summarized in Withering, Hongshai, and Menhuang.

FAQ

How do hand and machine kill-green differ? Hand-firing can adjust to the leaves and suits small batches of ancient-tree material, but batches vary more; drum machines are efficient and consistent, suiting large volumes of terrace material.

What temperature should the kill-green wok be? Industry experience puts it around 200°C, adjusted for the wok, leaf load, and condition of the fresh leaves.

Can you taste tea that was scorched? Yes. It has a smoky, burnt taste, and the infused leaves show scorched edges and spots.

What does under-fired tea taste like? It often tastes green, astringent, stuffy, and sour, and the infused leaves show red stems and red leaves.