My tea gets drier and harsher as it cools

In short

Nothing is extracting; the cup is closed. What changes is perception: astringency becomes more noticeable as tea cools, while the volatile aromatics that were balancing it have evaporated. This is astringency rather than bitterness, and the fixes are the astringency ones.

Likely causes, in order

Most likely first. Answer the question under each one before moving on — several of these look alike in the cup and are told apart only by what was done to the leaf.

1. 1. Aromatics have gone, leaving the structure exposed

   Technique

   Check: Was the cup poured several minutes ago, and did it smell much better when fresh?

   Fix: Pour smaller servings more often. This is the practical argument for small gongfu cups: a 40 ml serving is finished before the aroma has left it.

2. 2. The tea was already at the edge of astringency when hot

   Over-extraction

   Check: Was there a slight drying edge even in the first mouthful?

   Fix: Shorten the steep or reduce the leaf slightly. Cooling reveals astringency that was present and masked rather than creating it.

3. 3. Broken leaf or a high proportion of fines

   Leaf quality

   Check: Is there dust at the bottom of the packet or the cup?

   Fix: Astringency comes disproportionately from small particles. A whole-leaf grade of the same tea shows the effect far less.

4. 4. Hard water accentuating the drying sensation

   Water chemistryInferred by TeaHQ, not established

   Check: Does the same tea behave differently with filtered water?

   Fix: Try a filtered water. Mineral content interacts with the compounds responsible for astringency, and a cooling cup is where the difference is most obvious.

5. 5. A large cup that was always going to go cold

   Equipment

   Check: How long does it take you to drink a full mug?

   Fix: Use a smaller or taller cup. A tall narrow cup exposes less surface and cools more slowly, which is exactly what a yunomi is shaped for.

Tea types this applies to

• Black tea
• Green tea

Brewing methods this applies to

• Western brewing (teapot or mug) — A small amount of leaf in a large volume of water, steeped once for a few minutes and then strained off. The approach most English-speaking drinkers already know, and the one most teas sold in the West are made for.
• Mug infuser brewing — Loose leaf in a basket inside a mug — the most common way loose tea is actually made, and the method most often responsible for people concluding that loose leaf is not worth the trouble.

Related problems

Sharing a cause category, a tea type or a brewing method with this one.

• There is an oily film on the surface of my tea — An iridescent or dull skin sits on the surface of a cup or pot, breaking into patches when disturbed and clinging to the side as the level drops.
• I bought a water filter for my tea and it changed nothing — A filter jug or tap filter was bought specifically to improve the tea, and the cup tastes the same as it did before — with the same dullness, the same film and the same scale in the kettle.
• Tea from my flask tastes stewed by mid-morning — Tea that was fine when it went into the flask is dark, thick and harshly drying an hour or two later, and worse again by lunchtime.
• My green tea goes yellow or brown in the cup — The liquor is green when poured and turns yellow, olive or brownish within minutes, sometimes with a darker rim.
• My green tea tastes flat and looks dark in this house — A delicate green tea that tasted bright elsewhere comes out dull and heavy here, with a darker, browner liquor than it should have and none of its aroma.

Sources