FoodBanter.com - View Single Post

10/30/05

> Temperature is one of the most difficult physical things to measure and
> those digital thermometers are fairly unreliable. I bought a digital
> thermometer for 20 bucks and the reading it gave for freshly boiled
> water was 96 degrees (celcius). The best thing to do if you want it
> accurate is to add cool water to freshly boiled water. using physics
> calculations you can get the following ratios. make sure your teapot is
> hot otherwise it will act as a heat sink and cool the water too much.

Adrian, how high are you? Off the top of my head, I'd say about 2000 meters,
more or less. But, then it might be your thermometer's bad.
>
> To cool boiling water to 80ºC add 100ml room temperature water to
> 400ml fresh boiled water.
> To cool boiling water to 85ºC add 75ml room temperature water to 400ml
> fresh boiled water.
> To cool boiling water to 90ºC add 50ml room temperature water to 400ml
> fresh boiled water.
> To cool boiling water to 95ºC remove lid from kettle and stand for 30
> seconds.

I think one of the most crucial elements here, with a nod to Dog Ma, is the
thickness and density of the wall of your brewing vessel, since it is this
wall that absorbs most of the heat. This element would vary your
calculations above by quite a lot. My advice is to test for yourself, using
a thermometer at first.
>
> the temperature you need for your tea depends in what tea (green, light
> oolong, black etc) you are drinking.

Again, the best approach is trial and error.

snip

Michael