What the heck - it's Saturday, and my favorite show is on WUMB. Somebody
more awake can check the arithmetic and assumptions.

Approximate latent heat of evaporation of water: 550 cal/g at 80C.
(According to my ancient 10th ed. Lange's Handbook of Chemistry, it
varies from 574@40 to 540@100.) So allowing one gram to evaporate from
100g will drop the temperature 550/100=5.5 degrees C. One gram is about
the amount that will just wet the lid and pot. So pouring 80C water on a
just-filled pot and letting it dry will (ignoring heat capacity of the
pot; per below a reasonable approximation) drop the overall temperature
by about five degrees.

Heat loss by radiation is nil (easily demonstrated by putting a hand
next to and then above a full, hot pot, or solving the Stefan-Boltzmann
radiation equation), and by passive convection only a little greater. So
for you hot-pot fanatics, rinsing the outside of a previously dry pot
may not be an optimal thermal-management strategy, though it's no doubt
fun splashies.

Now to that other matter: step-drop from cold pot. A small sampling of
at-hand Yixings in the 4-oz class gives a mean weight around 120g, and
the specific heat of such artificial rocks is about 0.2. Assuming a
starting water temperature of 80C and pot at 20C, ignoring leaf (as one
does), I get the pot warming by about 48 degrees and the water cooling
by 12, for an equilibrated temperature of 68.4 degrees.

Conclusion (for those who care about such matters): pre-warming the pot
is GOOD (especially if you wipe it dry immediately); post-rinsing it is
BAD (unless you keep it wet with hot water until steeping is done).

I hope that that excursion has helped to disobnubilate this perilous
operation.

-DM

i love science!

You had me until "hot-pot", but the use of the hyphen got me thinking
about the Chongqing speciality. Science on an empty stomach does not
a happy punter make.


Toodlepip,

Hobbes