Home science: teapot cooling.

Hypothesis: tea cools faster if the teapot is not covered with a towel.

I don’t have a well-controlled setup nor instruments with lab-grade low margin of error, so the control for scientific rigor is limited. The ambient temperature likely varied during the test, though never reached a point for the apartment thermostat to turn on the HVAC. There is slight variation of the exact time of temperature measurement, but under a minute. I would love to repeat this with better controls and with pouring off quantities of liquid at intervals. This crudely measures heat loss to surrounding air if the air movement is unrestricted around the glass container vs. if it is somewhat restricted by a towel draped over the container.

Bodum Ibis electric kettle
Bodum Assam 1.5L teapot. The infuser on this model does not have silicone liners or rim and the handle is borosilicate glass.
Folding thermocouple kitchen thermometer.
Terrycloth hand towel
Cork coaster.

Temperature was measured in Fahrenheit by inserting the probe into the spout and holding the tip against the infuser at the bottom-left hole adjacent to the seam that aligns with the spout.
The teapot was sat atop the cork coaster, which is only slightly wider than the teapot’s base.
Water was boiled in the kettle and once that switched off poured into the teapot, filling to the point where the infuser cylinder stops in the top collar (there’s a space of overlap of the two pieces of stainless steel.) The top was then placed on it with the plunger in the up position. After 5 minutes the plunger was pushed to the down position and remained there for the duration.
Temperature measurements were taken at roughly 0, 5, 15, 30, 45 and 60 minute intervals.
Covered was performed first. Uncovered was performed immediately after. This does mean the teapot had a different starting temperature, being warmer for the uncovered test.
No liquid was removed during the test and the teapot was not moved. This likely reduced heat loss somewhat and left the liquid undisturbed so any temperature stratification would persist.

Raw measurements.

Covered lost about 42 degrees while uncovered lost 57. The uncovered higher 0 minute temperature and roughly 1 degree lower heat loss at 5 minutes is likely due to the teapot being at a much higher starting temperature.

TimeUncovered – Covered
Uncovered less Covered temperature difference.

Again we see the higher starting temperature and slightly reduced initial heat loss.

Heat loss relative to previous measurement.

Heat loss seems to peak at 30 minutes.