Ice steeping (kōridashi)
Ice cubes placed directly on dry leaf and left to melt, with no water added at all. The liquor arrives as the ice goes, drop by drop, and there is very little of it. It is the coldest steeping in ordinary practice and produces the most concentrated sweet extraction of any.
Also called ice brew, ice-drip tea, melting-ice steeping.
How it works
Melting ice holds the water at the bottom of the liquid range for as long as any solid remains, which is colder than refrigerated water and much colder than any hot steep. At that temperature the compounds that read as savoury and sweet still dissolve, slowly, while those responsible for bitterness and astringency barely move. Because the only water present is what has already melted, the leaf sits in a very small volume throughout, so what does dissolve stays concentrated instead of being diluted across a cupful. The result is a viscous mouthful rather than a drink, and the spent leaf is usually then brewed conventionally rather than thrown away.
Why choose it
It isolates the sweet and savoury side of a shaded or high-grade Japanese green tea more completely than any other method, and it needs no equipment beyond a lidded dish and a freezer. It is also the clearest demonstration available that temperature selects what comes out of a leaf rather than simply how fast.
Equipment
- Shiboridashi — Porcelain or stoneware, glazed or unglazed
- Glass teapot — Borosilicate glass
- Houhin — Glazed or unglazed porcelain and stoneware; Tokoname and Banko clays are common
Tea types it suits
Recorded on the method rather than inferred from the catalogue. A type missing here is not ruled out; it simply has not been written down.
Common problems
- Expecting a cup — a generous handful of ice yields a few sips, and that is the method working correctly
- Adding water to hurry it along, which turns it into an ordinary cold brew
- Using a robust or roasted tea, which gives almost nothing at this temperature
- Discarding the leaf afterwards, when it still has most of its hot-water extraction left
Diagnosed problems
Written from the symptom, with the likely causes in order and a question to rule each one out.
- My tea tastes weak or watery — The cup is thin and has little flavour, however long it is left to steep.
Teas with parameters authored for this method
16 teas have a parameter set written for ice steeping (kōridashi), in alphabetical order. Each row is transcribed from that tea’s own record.
| Tea | Leaf (g/100 ml) | Water (°C) | Authored infusions | First infusion (s) |
|---|---|---|---|---|
| Asamushi sencha | 5–9 | 0–5 | 1 | 3000 |
| Chumushi sencha | 5–8 | 0–5 | 1 | 2400 |
| Fukamushicha | 4–6 | 0–5 | 1 | 1500 |
| Guricha | 5–8 | 0–5 | 1 | 3000 |
| Gyokuro | 6–12 | 0–5 | 1 | 3600 |
| Kabusecha | 6–12 | 0–5 | 1 | 3600 |
| Kagoshima sencha | 5–9 | 0–5 | 1 | 3000 |
| Karigane | 4–7 | 0–5 | 1 | 1800 |
| Mecha | 4–7 | 0–5 | 1 | 1800 |
| Mizudashi sencha | 5–8 | 0–5 | 1 | 2400 |
| Sayama sencha | 5–9 | 0–5 | 1 | 3000 |
| Sencha | 4–8 | 0–5 | 1 | 2700 |
| Shincha | 4–8 | 0–5 | 1 | 2700 |
| Tamaryokucha | 5–9 | 0–5 | 1 | 3000 |
| Uji sencha | 4–8 | 0–5 | 1 | 2700 |
| Yame gyokuro | 6–12 | 0–5 | 1 | 3600 |
Other cold brew methods
Same family, so the approach is close — the vessel, the ratio and the intent still differ.
- Cold brew tea — Leaf steeped in cold water in the refrigerator for several hours. Low temperature extracts the sweet and savoury compounds readily and the bitter and astringent ones barely at all, producing a cup that is genuinely different rather than simply a chilled version of a hot one.
- Sun tea — Tea left to steep in a jar in direct sunlight for several hours. It is a traditional American summer method, and it is the one preparation in this catalogue where TeaHQ recommends a substitute rather than the method itself.
Sources
This page is TeaHQ synthesis. No external source stands behind the description of this method. It is written from common practice as TeaHQ understands it, and the parameters in the table above come from each tea’s own record rather than from this page.
The numbers for this method are held per tea, never on the method itself. Where a tea has no set written for ice steeping (kōridashi), TeaHQ shows nothing rather than converting its numbers from another style — a scaled ratio and a halved time read as an answer while being one nobody authored.
Written comparisons
Where TeaHQ has set this method against something it is routinely confused with, and argued the differences out in full.
- Ice steeping (kōridashi) vs cold brew — Two cold extractions with different water and different intent. Cold brew adds cold water and waits hours; ice steeping adds no water at all — ice is placed on dry leaf and the liquor arrives drop by drop as it melts.