Following a comment asking if silver would not cool down fastest because it has the highest heat conductivity, I made a first set of experiences on Monday March 12. A reader mentioned to me that the speed heat drops is also closely related to the mass of heat. He suggested that I use the same amount of water for each different tea vessel. This may probably not be ideal either, I think, because then some pots would be full and others not. So I chose to find vessels with more similar sizes, but I would fill them like in normal brewing conditions.
So here are the results of my new experiment:
A. Conditions: - The water in my tetsubin reached the heat of 95° Celcius. - Room temperature was 22.5°C - None of the 3 tea vessels were pre heated.
B Results: B1 The silver teapot (190 grams for 18.5 cl of water): 89.5°C at 5 seconds approx after the boiling water was poured inside, 79°C after 5 minutes while staying completely covered with the lid, 70°C after 11 minutes.
B2 The big gaiwan with drawings (right, 218 grams for 15 cl of water): 85°C at 5 seconds approx after the boiling water was poured inside, 71°C after 5 minutes while staying completely covered with the lid, 64°C after 11 minutes.
B3 The porous and rather thick HungNi Shui Ping teapot (left, 148 gr for 16.5 cl): 88°C at 5 seconds approx after the boiling water was poured inside, 76°C after 5 minutes while staying completely covered with the lid, 68°C after 11 minutes.
C Findings - The silver teapot handles heat best in the first crucial moments of the infusion. - Once warm, clay kept the heat at least as well as silver, - Glazed ceramic (even this very thick gaiwan) had the largest drop of temperature.
D Conclusions - Preheating is very, VERY important! Escepcially with small teapots. - These different properties can be useful for different teas: fresh green and red teas will benefit from the drop in heat of ceramic, because it will reduce the astringency that usually appears toward the end of the infusion. Clay will be a good choice for teas (good roasted oolong and cooked puerh, for instance) that can infuse for long times at high temperature. Such tea will have more body and longer aftertaste. - The silver teapot combines 2 properties of clay and ceramic, which gives its infusions a unique taste. It handles heat at least as well as clay and it is neutral, true to the taste of tea like glazed ceramic.
(Note: next time I will experiment with a bigger clay teapot to verifiy that the volume was not the major factor in this experiment).