There are 4 big ways that heat can travel: convection, conduction,
radiation, and evaporation. Let's think about these one at a time.
This happens when air moves around. It picks up heat in one place
and moves it to another. In order to prevent this from happening, you
want to keep your cup of tea somewhere where the air is very still, so
no heat can get away. Perhaps you may want to put a lid on it.
This is heat that radiates off of something. For example, if you
put your hand near (but not touching!) a hot stove, it will feel warm
there. This is energy being radiated straight off of the stove and onto
your hand. To prevent this, you want the surfaces near the tea to be
the sort that don't absorb much heat. For example, a white surface will
absorb much less heat than a black one. (Think of riding in a white car
vs. a black one when it's really hot outside.) A shiny surface will
absorb even less, since it reflects heat back where it came from.
This is when water evaporates and carries heat away. This can be
especially important with a hot liquid like tea, since the steam can
carry a lot of heat. In order to prevent heat from escaping like this,
you will want to keep the container closed and water-proof, so the
moisture can't get out.
Last but not least. This is what happens when something hot
physically touches something cold. Heat moves from the hot surface into
the cold one, warming it up. To keep this from happening, you should
use a material that heat can't move through very easily. But how do you
know what sort of a material that is? Try some experiments. Wrap up a
hot cup of tea in each of the insulators that you're thinking about.
Set your hand on the outside of the insulator and see how hot it feels.
The hotter it feels on the outside, the more heat is escaping from the
I think from here you should be able to figure out exactly what material (or materials) to use on your own. Good luck!
(republished on 07/27/06)