Brewing Thermometer
Definition
A device for measuring water temperature when brewing tea, ranging from clip-on probes to digital infrared and built-in kettle displays. Accurate temperature is critical for sensitive teas.
Why it matters
Tea is highly temperature sensitive. A few degrees of difference in water temperature can dramatically change how catechins, caffeine, and aromatic compounds extract from the leaf. Greens and shaded Japanese teas typically perform best at 60 to 80 degrees Celsius, oolongs at 85 to 95 degrees Celsius, and black, pu-erh, and most herbal infusions at 95 to 100 degrees Celsius. Variable-temperature electric kettles eliminate the need for a separate thermometer for most drinkers. For those using stove-top kettles, charcoal kettles, or borrowed equipment, a small probe or infrared thermometer provides confidence that water has reached or fallen to the right temperature. Some Japanese setups use a yuzamashi (cooling vessel) to manually drop boiling water by 10 to 20 degrees Celsius before pouring. More experienced brewers often learn to judge temperature by visual cues such as bubble size in the kettle (shrimp eyes, crab eyes, fish eyes) and surface activity, a tradition formalized by Lu Yu in the Cha Jing.