A Mylar blanket, also known as a space blanket or emergency thermal blanket, is specialized survival gear designed to manage body temperature in extreme conditions. It is made from a thin, plastic sheet coated with a metallic reflecting agent. The primary function of this reflective surface is not to generate warmth, but to reflect up to 90% of the body’s radiant heat back toward the user. The blanket also provides an effective barrier against wind and moisture, preventing heat loss due to convection and evaporation. These qualities make the compact, lightweight blanket a powerful tool for preventing hypothermia in emergency situations.
Maximizing Body Heat Retention
The most common error when using a thermal blanket is wrapping it too tightly against the body. Mylar material has negligible insulating value and does not trap heat like a thick wool blanket. Its effectiveness relies on creating an air gap between the body and the reflective surface. This gap allows the air to be heated by reflected body warmth, providing a layer of insulation. Without this space, the blanket pressed directly against skin or clothing quickly conducts heat away, significantly reducing its benefit.
To maximize heat retention, fully unfurl the blanket and wrap it around your entire body, securing the edges to minimize air movement. Tucking the material around the feet and neck is important to create a thermal bubble that traps the heated air. Since significant heat loss occurs through the head and neck, covering the head while leaving a small opening for breathing is highly recommended.
The blanket performs best when used as a reflective liner inside another layer of material. Placing the Mylar inside a sleeping bag or wrapping the exterior of a conventional blanket significantly boosts overall thermal performance. The blanket should be placed close to the body, often with the shiny side facing inward, to bounce infrared energy back to the source.
Using the Blanket as a Survival Tool
Beyond personal wrapping, the blanket’s properties lend themselves to several other survival applications. Its highly reflective, mirror-like surface makes it an excellent signaling device for search and rescue personnel. By holding the blanket taut and flashing the metallic side toward a distant aircraft or ground team, you can direct a burst of light visible from a great distance. This heliograph technique is an effective way to attract attention during daylight hours.
The material’s resistance to wind and water allows it to be quickly fashioned into an improvised shelter. You can create a simple lean-to or overhead tarp by stringing the blanket between trees or using sticks to form a frame. This structure serves as a windbreak and rain barrier, reducing heat loss from convection and moisture. In hot climates, the blanket can also be used as a sunshade, reflecting solar radiation away from the user to provide a cooling effect.
A crucial secondary use is as a ground barrier to combat conductive heat loss. Placing the blanket on the cold ground beneath a sleeping bag or directly under a person prevents body heat from being lost to the earth. It also acts as a waterproof footprint, keeping bedding and clothing dry from ground moisture. When setting up a fire, the blanket can be placed behind the user to reflect the fire’s radiant heat back onto the body, maximizing warmth.
Handling Common Issues and Misconceptions
One of the most persistent challenges with Mylar is managing condensation. Because the material is non-breathable and acts as a vapor barrier, moisture from sweat or breath becomes trapped inside. This moisture can saturate clothing, accelerating heat loss through evaporation and increasing the risk of hypothermia. To combat this, ensure some ventilation is maintained and avoid using the blanket inside a completely sealed space.
The material is fragile, tearing easily when snagged or subjected to high stress. Its fragility is compounded by the loud, crinkling noise it makes with any movement, which can be a drawback in situations requiring stealth. Users should handle the blanket with care and attempt to smooth down any rough edges on surfaces it touches.
A serious safety concern is the blanket’s flammability, as the thin plastic material can ignite quickly from a single spark. When using the blanket near a campfire, it must be kept a safe distance away to prevent accidental fire and severe burns. For proper storage and potential reuse, the blanket should be carefully folded back into its compact form, though frequent use will degrade the metallic coating over time.