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Emergency blankets go by many names such as space blankets, Mylar blankets, thermal blankets, etc, but no matter the name, their function is the same. They are a low-weight, low-bulk blanket made of heat-reflective thin plastic sheeting. They are not only used by people but are also used on the exterior surfaces of spacecraft for thermal control.
The design of the emergency blanket reduces the heat loss in a person’s body, which would otherwise occur due to thermal radiation, water evaporation, or convection.
Their compact size and light weight make them ideal when using as an addition to our survival kits and when the needs arise, they are a great item that has multiple uses.
Our body loses heat naturally all the time. Most of these times it is a good thing such as when we’re trying to cool off during a hot summer’s day, but there are also times that our body can’t keep up with what we’re losing.
There are three different ways in which our body loses heat. These include:
- Radiation – heat emanating from the surface of our skin and dissipating.
- Convection – think of the wind blowing across your skin’s surface – nice on a humid day when we’re sitting in front of a fan, but bone chilling on a blustery winter day.
- Conduction – as when we sit on a chair after somebody else and can feel the ‘warm spot’ that they left.
The blankets work to keep you warm by their very design. The blankets themselves do not create heat but as an impermeable metalized plastic sheet, they trap up to 90% of the radiated body heat that would normally escape off into the environment. So they mainly keep us warm with the heat we’re already always generating and losing!
But as these blankets are not insulative, they do not prevent heat loss by conduction (heat-transfer). They can, however, be used very effectively against heat loss through convection. Wrap the blanket around exposed skin and you have a wind breaker to keep that breeze from blowing across your skin and whisking the heat away.
Apart from the usual use of the blankets, they can become incredibly useful in a survival situation for such things as signalling, collecting rainwater, fire starting, and more. Check out our list of uses here.