I think you are assuming that all "vessels" absord heat at the same rate.
Even if you don't pre-heat the vessel by pouring boiling water in it, its
temperature may vary a great deal. A thick, cold mug is going to pull the
temperature down a lot further than a warm bone china teapot!
"Tom Blorst" > wrote in message
om...
> Hi Everyone,
>
> I've been conducting an experiment with water temperature lately, and
> have gotten some results that surprised me.
>
> In brief, I've always had a problem that many others here have
> mentioned -- how to estimate the temperature of water (mainly for
> sensitive green teas) without resorting to a thermometer.
>
> A method that had been working well for me was to pour boiling water
> into a mug and let it sit for a minute or two, then add the leaves. I
> figured this would get the temperature down to about 180F, and it
> seemed to work great.
>
> One day, though, I decided I'd actually check to see what kind of
> temperatures it was producing, and, when I got the thermometer out, I
> found that it was more like 150F. So I tried pouring water into a
> cold mug, waiting a few seconds (basically just long enough for it to
> heat the mug), then taking the temperature. I found that even boiling
> water (212F, since I'm at sea level here) drops almost immediately to
> about 170F when poured into a room-temperature vessel, and this 170F
> figure is consistenly repeatable. This seems awfully low -- is my
> thermometer broken?
>
> I've always read (and, of course, believed) that you lose about 10
> degrees F to the heating of the vessel, but it's looking like I'm
> losing a lot more. If anyone else can duplicate these results, I can
> see at least two consequences it would have:
>
> 1) It underscores the importance of pre-heating the cup/pot for black
> teas that really do need 195F-plus water, which is a step that I've
> often skipped in the past.
>
> 2) It makes the preparation of 170-180 degree greens much easier --
> just let the water boil, pour it into the vessel, wait a minute, and
> add the leaves.
>
>
> Any thoughts?

"juanon" > writes:

> Even if you don't pre-heat the vessel by pouring boiling water in it, its
> temperature may vary a great deal. A thick, cold mug is going to pull the
> temperature down a lot further than a warm bone china teapot!

Of course you are correct as you state this. But a thick, cold mug will hold
heat longer than a thin bone cup or pot. It's a matter of rate of heat
transfer. In the long run, the tea will reach ambient temperature; it will
get there more quickly with a thin vessel. There is no possibility of it
becoming colder than that (unless the vessel was pre-chilled, and I assume
that is not the case).

This time of year our kitchen is chilly in the morning, and when I make my
Irish Breakfast (same blend for probably ten years now) and pull a cold cup
out of the cabinet, I'm needing to heat extra water for that pre-heating of
both pot and cup.