see also:

• photography and camping main index page

• Thermos type metal dual wall vacuum bottles are very useful for picnics and for reducing the frequency of getting your stove out when camping and you just want a coffee or tea.

• the larger the capacity of the bottle and the more water you have in there, the slower the drop in temperature
  • most will drop around 2degC per hour for the 1st 12hrs from almost boiling with ambient temperatures around 20degC
    • the 450mL bottle dropped a little faster at around 2.5degC per hour
  • the rate of temperature drop SLOWS as the temperature gets closer to ambient temperatures
  • at 24hrs after adding initial almost boiling water to capacity and only opening twice during the time for brief temperature measurements:
    • 1.8L was 53degC (started at 83degC)
    • 1L was 53deg C (although started at 93degC)
    • 450mL was 43degC (started at 83degC)