An emergency blanket, commonly referred to as a space blanket or Mylar blanket, is a lightweight survival tool made from a thin sheet of polyethylene terephthalate (PET) film. This material is coated with a metallic reflecting agent, typically vaporized aluminum. The blanket’s design is not based on traditional thermal insulation like down or fleece. Instead, it functions primarily by reflecting up to 90% of the user’s radiant body heat back towards them, helping sustain core temperature in cold environments.
Primary Use: Retaining Body Heat
The primary goal when deploying an emergency blanket is to prevent the four main types of heat loss: radiation, conduction, convection, and evaporation. To maximize the effect of reflecting radiant heat, the silver or reflective side of the blanket must always face inward, directly toward the user’s body. This surface acts like a mirror, bouncing infrared energy back to the skin to maintain warmth.
A frequent error involves placing the blanket directly against wet clothing or the ground, which rapidly causes heat loss through conduction. The highly conductive nature of the metallic coating means that any direct contact with a colder surface will quickly draw heat away from the body. Therefore, it is important to first establish an insulating layer using clothing, leaves, or a sleeping bag between the body and the blanket.
Before wrapping, ensure any wet clothing is removed or wrung out, as water significantly increases conductive heat loss. Once wrapped, the blanket should be draped loosely over the body, allowing for a small layer of trapped air to provide additional insulation. Tucking the edges securely around the neck, shoulders, and feet is necessary to minimize heat loss from convection. Preventing air circulation limits the movement of cold air across the warm skin surface.
When using the blanket in a sitting or prone position, it is helpful to create a hood or secure the top edge around the head. A significant amount of body heat radiates from the head and neck, and covering this area improves overall thermal retention.
Beyond Personal Warmth: Alternative Applications
The versatility of the emergency blanket extends far beyond its primary role of wrapping an individual. Its large, thin, and reflective surface makes it a powerful tool for visual signaling during a distress situation. By holding the reflective side taut and using it to mirror sunlight, a user can create a brilliant flash visible from a great distance, even on a cloudy day.
The blanket can be quickly repurposed as a makeshift shelter or weather barrier to protect against rain or direct sun exposure. By stringing a cord between two trees or elevated points, the material can be draped over the top to create a lean-to configuration. This overhead canopy provides protection from precipitation and reflects solar radiation outward, creating a shaded space beneath.
The waterproof nature and large surface area make the blanket useful for collecting water in a survival setting. By spreading the material on the ground in a slight depression, it can function as a temporary basin to catch rainwater runoff. Alternatively, the blanket can be used to harvest dew by spreading it out overnight and then wringing the collected moisture into a container the following morning.
The metallic sheeting can also be used to enhance the efficiency of a small fire or heat source. By placing the blanket on the ground or wall behind the heat source, the reflective surface will redirect thermal radiation back toward the user or shelter. This simple technique significantly improves the usable warmth generated by a limited fuel supply.
Avoiding Common Mistakes During Deployment
Misunderstanding the material’s properties often leads to common mistakes that reduce the blanket’s effectiveness. One frequent error is wrapping the blanket too tightly around the body, which minimizes the crucial air gap needed for insulation. A tight wrap also promotes the buildup of condensation, causing moisture to accumulate on the inside surface.
This collected moisture is a major problem because it increases conductive heat loss from the skin, defeating the blanket’s purpose. The user feels a chilling effect as the trapped water evaporates or transfers heat away from the body. Maintaining adequate ventilation while still preventing convection loss is a delicate balance required for optimal performance.
Users must remember the blanket does not generate heat; it only works by reflecting the heat already produced by the body. If the user is already hypothermic or has a low core temperature, the blanket will only slow the cooling process rather than providing warmth. In such cases, an external heat source or physical activity is necessary to raise the core temperature.
The thinness of the polyethylene terephthalate material makes it highly susceptible to tearing and puncture damage from sharp objects or rough terrain. Handling the blanket gently during deployment and securing it with tape or clips minimizes the risk of damage. The material offers very little resistance to wind when unsecured, meaning a strong gust can easily tear the material or pull it away entirely.