As it’s getting colder it’s a good time to revisit the uses of mylar blankets in survival situations…and to warn people that these things can kill you if you use them incorrectly.
Mylar blankets, also called space blankets and emergency blankets are essentially a large sheet of mylar designed to be wrapped around you to keep you warm. Most people have one somewhere, in their backpack or car…sensible places to be sure but do you actually know how to use one?
That sounds like a really stupid question but bear with me on this.
A true story about using a very decent quality hospital supplied mylar blanket
Mr Smith was a previously fit but elderly gentleman who had come into hospital for a routine hernia repair. As is common with elderly people he had a low percentage of body fat and as the operation wasn’t as straight forward as we had hoped his temperature dropped a little so at the end of the case he was covered with a blanket and a mylar blanket put on top to keep the heat in.
Okay, mistake number one was that the anaesthetist hadn’t used an internal core temperature probe. He was using a skin thermometer which of course under the operating lights was reading higher than Mr Smiths core temperature.
Mistake number two was that the tech was newly qualified, as was the anaesthetist and neither of them picked up on this.
Mistake number three was the pair of them standing there scratching their heads wondering why the gentleman’s temperature had dropped a full degree AFTER he was covered up.
Mistake number four was not calling help.
This combination lead to Mr Smith lying on an operating table in a fully equipped and well staffed hospital slipping into hypothermia in front of their eyes.
Myself and a colleague were called and the look on everyone’s faces when we ripped off the mylar, swapped the blanket for a sheet and trained the operating lights on ‘our’ patients chest area was a sight to behold. These people had no clue how to correctly use a mylar blanket. An internal temperature probe gave Mr Smiths temperature as 34.2 ºC. Hypothermia is a core temperature of 35ºC or below.
He showed a drop in temperature after he was covered up because no external heat was getting to his body. They had wrapped a hypothermic guy in foil which was reflecting all external heat away from him.
Used incorrectly mylar blankets can actually make you colder. You have to be generating heat in order to trap that heat and Mr Smith wasn’t, and you won’t be either if you are hypothermic when you wrap yourself in one. You will also not have the benefit of a core temperature probe and a hospital environment that can put things right when they start going wrong.
Sitting by a campfire wrapped in mylar will not warm you that much as the heat from the fire will reflected away from you, if you are cold, you will stay cold, it really is as simple as that. Wrapping a hypothermia victim in mylar will do them no good at all and can even cause their core temperature to continue dropping particularly if they are lying on a cold surface such as snow or frozen ground.
Shivering, which generates heat, stops at different temperatures for different people but severe, coma or death inducing hypothermia when shivering has stopped and the body starts to shut down can occur from 33ºC and lower…there’s not much leeway in the human system.
The optimum time to wrap up in mylar is when you START to feel slightly chilled.
The way you wrap yourself in mylar can also have a profound effect on how warm you will be. These emergency blankets are notoriously flimsy and will flap around in the slightest breeze. For optimum warming, take off your jacket, wrap the mylar poncho style around you, including over your head and then put on your jacket and hood or hat. If you get too hot, undo your jacket zip to let some of the heat out or uncover your head for a few minutes.
Remember the mylar does not possess breathability properties so beware of moisture building up from sweat. The optimum is to be warm and dry not warm and wet, or even warm and damp.
Mylar is waterproof so if you have a jacket zip failure wrapping the blanket around you will keep the rain out, again if it’s at all windy put it under your jacket.
Happily there are many, many uses for mylar blankets and as they are cheap and lightweight you should have access to several of them, particularly if you are out hiking or driving in winter. The ultra cheap ones are also ultra lightweight and will tear far easier than a mid-priced product but any are better than none!
So, onto a few other uses for this versatile piece of kit:
1. Position the blanket behind a campfire so that the heat is reflected back towards you rather than lost. Mylar melts at 254°C so there is no fire danger. If you have a second blanket, position it behind you. This will ‘bounce’ the heat around and will make that little area positively toasty compared to the area outside of the blankets.
2. Cut up the blanket to line boots and gloves. Fingers and toes are areas that are far more sensitive to both frost nip and frost bite.
3. Mylar is waterproof and using it on top of a ground sheet, or even as a ground sheet will prevent damp and also retain heat where you need it.
4. It’s reflective properties make it an excellent sunshade. It will be many degrees cooler underneath the shade than in full sun.
5. They are great for catching rain to give you a top up water supply. Either a natural depression in the ground or one you make yourself will suffice.
6. Building a soil or rock ‘casing’ and lining it with the blanket can make an okay solar oven. Position facing the noonday sun and cut the food into small pieces. Slivers of meat rather than chunks will cook more quickly and thoroughly.
7. It’s reflective properties make it an excellent signal that acts like a giant signal mirror. If you are moving on place soil or rocks on top leaving the shape of an arrow uncovered which points to your direction of travel.
8. Small strips of mylar make great fishing lures, fish are attracted to shiny surfaces.
9. These blankets are quite strong and can easily be fashioned into a sling in an emergency. Cut a wide strip place around the broken arm and tie at the back of the casualties neck.
10. A thin strip can be used as a makeshift tourniquet.
11. Put on the inside of blacked out windows will prevent heat loss through the glass. Blacked out windows will a) stop dazzle outside and b) absorb any heat at all even from weak sunlight.
12. Positioned behind a wood stove or radiator will throw out heat into the room rather than letting the wall behind it absorb the heat.
13. Positioned behind candles or lanterns the light will be reflected back into the room. You will be surprised how much extra light you get from this.
14. Birds hate mylar, the changing reflections and constant movement keeps them off the fruit bushes and away from the veggies.
15. Placed inside a duvet cover they will prevent heat loss during the coldest part of the night. The crinkling noise is a bit irritating, but it’s better than freezing if there is no heat source in the house.
16. Placing them over the windscreen of your car whilst the car is still warm from your trip prevents ice build up on the glass. Just trap the ends of the blanket in the doors.
17. As they are so light putting them over the veggie beds during the hottest parts of the day stops the plants shrivelling. It also cuts down on moisture loss due to evaporation.
18. Cut into strips and plaited they make extremely strong emergency cordage. I wouldn’t trust a mylar rope for rappelling etc as the texture of the fabric allows it to slip a little.
19. Left folded but out of its plastic wrapper it can be used as a reflective fire starter. I haven’t tried this one, but I am assured by a Boy Scout it works.
20. Their reflective properties make them excellent for signalling.
21. They are invaluable under picnic blankets to prevent damp coming through.
22. The Boy Scout tells me that once your laundry has stopped dripping, placing it on a mylar blanket in the sun dries it double quick.
23. Snow will melt faster placed on mylar even in weak sunlight.
24. Use as cooking foil to cook food in the embers of a fire.
25. Cut into strips they make great trail markers.
26. In hot weather wrap trapped game/food to keep it cooler. Tie up the corners and suspend from a tree branch into water.
27. Similarly hoist the food cache up into a tree to keep it way from animals.
28. Turn kids into aliens and robots on school dress up days or rainy days at home.
29. I’m told people use these blankets to build a simple shelter but I have doubts about this for several reasons:
If you have anymore uses for mylar blankets please share them in the comments section.
Other bullet point articles you may be interested in: