Assessing water temperature through bubbles and sounds. Instead of relying on ‘dummy-proof’ kettles with settings for ‘green’, ‘oolong’ and ‘black’, why not just practise a little silent, mindful meditation by paying attention to the water and bring a little of the tea ritual into your life?
In my last blog “Romance of the Three Kingdoms” I related a movie scene where Cao Cao asked “What is the most difficult thing about brewing tea?” Indeed, from a slightly different perspective, one of the most frequently asked questions at teanamu’s tea open houses and tea appreciation masterclasses is, “What temperature should I brew this tea at?”
As humans, each one of us is different. We each require the most suitable environment for us to showcase our best. Some people work well in a chaotic manner, others prefer to have everything under control. “Horses for courses” is the saying that comes to mind.
Tea is no different to us. Different teas require different temperatures. The appealing characteristics of each tea can only be revealed by brewing at the suitable temperature for the proper length of time.
In ancient times, the temperature of water was called “huo hou” (火候, state/condition of fire) or “tang hou” (汤候, state/condition of the “stock”). The key in these Chinese terms is the character “hou” (候):- it means the “state of” and it also means “timing”.
So how can one know the right “hou” like the ancients without the use of a thermometer?
Zhang Yuan (张源) the Ming Dynasty scholar very helpfully listed 15 identification techniques grouped into 3 main types in his “cha lu” (茶录, a record of tea) written in around AD1595.
The first of the 3 types is “xin bian” (形辨) – to look at the “shape” to ascertain “hou”. Lu Yu wrote (in chapter 5) about the 3 boils. Looking at the bubbles is made possible because the water is boiled on an open fire in a uncovered “fu” (鍑 cast iron pot, see chapter 4 part 2). The first boil “yi fei” (一沸) is like the eyes of crabs (70°C-80°C) and is accompanied by the slightest and softest popping sounds from within the kettle. The second boil, “er fei”, occurs when the edge of the kettle or pot has continuous strings of bigger pearls, the size of small fish eyes (80°C-95°C). This is the best “hou” for brewing tea. When the water rumbles in the kettle like the rough seas, the water is in third boil or “san fei” (三沸) and is considered “old” or over-ripened and unsuitable for brewing tea.
The second method is “sheng bian” (声辨) or identification by sound. This is the most suitable method for use with modern electric kettles. Post-Song dynasty, the ancients used lidded copper pots to boil water. Hence, they tried to use the sounds of scalding water to ascertain the “hou”. They used descriptive terms like “chu sheng” (初声, the softest popping sounds), “chuan sheng” (转声, twirling sounds), “zheng sheng”(振声, shaking sounds), “zhou sheng” (骤声, trotting sounds). These are all sounds made by the air bubbles in the copper pots.
When the water reached actual boiling point in these ancient copper pots, there was no sound at all. Of course different types of kettle will make different sounds and in a way, modern kettles also produce no sound except what happens is the thermostat trips and the kettle stops boiling. So these descriptions are still very apt. Whenever I get a new kettle, I stick a thermometer into it the first time I bring water to a boil in it and I listen to the distinct changes of sounds. I try to remember what each temperature range sounds like and then feel rather intimate with the kettle. I strongly recommend you do this as it is a very interesting and even meditative exercise.
The third method of discerning water temperature is “qi bian” (气辨) meaning identification of “hou” by steam. Zhang Yuan describes the steam as having 6 stages: “yi lu” (一缕, first wisp), “er lu” (二缕, second wisp), “san lu” (三缕, third wisp), “si lu” (四缕, fourth wisp), “lu luan bu fen” (缕乱不分, indistinguishable threads of steam), and “yin yun luan rao” (氤氳乱绕, entwining mist). When the water boils, the steam will just “shoot through the sky” (“qi zhi chong guan” 气直冲贯). Next time you put the kettle on, take a minute to admire the steam from its wispy stage to “eager to burst through the sky” stage!
When water is heated, small bubbles first appear because of the air (and some water vapour) that is trapped in the water and, as it gets hotter, the air bubbles get bigger and less dense so that they float or move from the hotter areas (bottom) of the water to the less hot areas (top). The ancients figured this out through the sheer power of observation! Some steam or water vapour escapes from the water surface, then cools and condenses back to water and then the bubbles become smaller again. As heat gets circulated through the water, the bubbles expand and contract in this manner, producing the “crab eyes” and “fish eyes”. When the vibrations of the bubbles hit the frequency at which the kettle will vibrate, sound is produced. When about 90% of dissolved gases in the water have escaped from the water, the temperature is nearer to 100°C. At this stage, the bubbles will not undergo expansion and contraction but will dash to the surface of the water and escape as water vapour. This is the “rough seas” stage with steam “shooting through the sky”.
Without a thermometer, the ancients could only use their eyes and ears to judge the “hou” of water. Regardless of how one judges the water’s “hou” – by shape, sound or steam – the aim is water that is neither “over-ripened” nor too “tender”. Water that is still too “tender” is liable to inhibit the aroma and taste of most teas from seeping into the water, while water that is “over-ripened” has lost its stimulating effects and will “stun” the tea aroma. Hence the ancients said, “The most difficult task in brewing tea is ‘huo hou'”.
A skilled tea artisan requires an intimate understanding of the characteristics of tea, water, tea utensils and heat. Apart from that, a tea artisan should also be mindful and observant during the tea ritual – ensuring that the “marriage” of all these factors can result at one moment in a truly wonderful beverage for yourself and your tea friends. So instead of relying on “dummy-proof” kettles with settings for “green tea”, “oolong tea” and “black tea”, why not just practise a little silent, mindful meditation by paying attention to the water and bring a little of the tea ritual into your life?