Author Topic: How To Use A Mylar Space Blanket Correctly!  (Read 57351 times)

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Offline Bud Wiser

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How To Use A Mylar Space Blanket Correctly!
« on: June 09, 2010, 03:18:29 AM »
Mylar Space Blankets

After seeing a couple threads, and a few negative remarks about Space Blankets I started out with just a reply to them in the original thread.  As my reply began to grow longer, I decided I'd turn it into a completely new thread in this section and create more of a
"Space Blanket Primer" in the hope of correcting some misconceptions and maybe help some people out.

A mylar space blanket can literally be a life saver... if used correctly.  

If used incorrectly...   As my wilderness survival instructor once told me, "well they make a pretty good shroud to wrap your body in when the SAR workers carry your corpse out of the woods, so the news media aren't snapping pictures of your ugly corpse."

It would do one well to remember that when you merely throw a couple of Space Blankets into your BOB and "call it good" as far as your emergency shelter goes.

So, What are they and how does one use it correctly?

For starters...  There's only one kind to buy.  Period!  That is The Original SPACEŽ Brand Emergency Blanket.  It has been manufactured exclusively in the USA by a company called MPI since 1964.  They make one which is silver on both sides; one which is gold on one side and silver on the other; and they make one for the military which is OD green on one side and silver on the other.  For what it is, which may not seem like much, there's a lot of science and quality control which goes into the materials and manufacturing.  Developed by NASA, MPI are the people who then manufactured the material for NASA which was used on the lunar landing module.  

The material is still used by NASA and it is made by vacuum depositing a thin layer of pure aluminum vapor onto a thin poly substrate PET film material which results in a metalized polyethylene terephthalate or MPET.  The quality of materials, and the manufacturing process assures that there is a consistent reflection of 97% of radiated heat from the shiny silver side.  The ones which are Silver on both sides, if you look closely, you'll notice that one side is "shinier" than the other.  You use the more shiny side to reflect the heat back towards you.  One of the reasons they started making the gold color on one side was because people didn't realize there was a correct side to use on the all silver ones to get the maximum effect.  The other reason for the gold color was for use in signaling.  

For around $3.00 a piece, that's a pretty high tech piece of life saving material you have in your hands.  I have no idea what Chinese made, and other brand space blankets are made of and how reflective they are.  But for only about $3.00 each, why not get the best?  So when you buy one make sure it has the registered trademark on the label "Original SPACEŽ Brand Emergency Blanket,"  made in the USA and/or look for MPI somewhere on the label.  At about $3.00 a piece, I wouldn't want to try and save an extra $.75 to $1.00 buying a cheaper inferior version which I'm going to bet my life on.

What to do with it?  All it does is radiate heat, right?  That's it?  Well, sort of...  It has no insulating properties and when you open it up, it takes all of about 30 seconds for the plastic material to become as cold as the outside temperature.  It's only about a millimeter thick or there about, so obviously it's going to be somewhat fragile.  The wind will rip it to shreds if you don't use it correctly.  But, if you use it correctly, it will help keep the wind at bay, provide wind protection and not get shredded by the wind.  It will also shed water and keep you dry.  But most importantly, it reflects up to 97% of your body heat back onto you.

Before we really get into how to use it, we need to know how body heat is lost and how it applies to the use of a SPACEŽ emergency blanket. So lets look at the causes of heat loss, how it applies to the SPACEŽ emergency blanket, and at the end, I explain the best way to use it.

Convection: happens when wind blows against bare skin which speeds up the process of evaporation, which is another method of heat loss.  So, a wind barrier such as a SPACEŽ emergency blanket, can protect the body from losing heat through the process of convection.

Conduction: causes heat loss by having the skin in direct contact with objects or surfaces which are at a lower temperature than that of the body.  Therefore, we don't want to use a SPACEŽ emergency blanket wrapped around bare skin, or without a layer of insulation between you and the blanket.  Remember, your body is around 98 degrees in a normal state.  If it's 35 degrees outside, and you wrap a 35 degree plastic sheet around your body, you will lose heat through conduction.  If you are wearing a thick layer of wool, fleece or other insulating layer between you and a loosely wrapped SPACEŽ emergency blanket, then you will be protected against heat loss via conduction, and convection.

Radiation: When the temperature outside is cooler than the body, the body naturally emits heat into the surrounding air.  This is referred to as radiation.  This is where the SPACEŽ emergency blanket really shines and comes into it's own as a piece of life saving equipment as it reflects up to 97% of radiated heat back towards the direction it came from.

Evaporation:  As perspiration or sweat, in the form of water on the skin evaporates, it turns into a vapor state as it is absorbed into the air around us.   This action creates a cooling effect on the skin and provides yet another means of heat loss from the body. So, the SPACEŽ blanket, being non-permeable and wind proof is wrapped around the body and closed off, the water vapor released from the body will become trapped by the blanket having no where to escape.  Thus, it will increase the humidity inside, and theoretically reducing heat loss by preventing evaporation.  

This can be a double edge sword and get someone into serious trouble, because as you increase the humidity within a trapped space, you become wet.  And your clothes become wet.   As long as you remain wrapped up inside, you should stay warm...  but you'll be warm and wet.  In a survival situation, we don't want to be wet.   At some point, you'll need to get out from under it to attend to other survival necessities, such as keeping that fire going or building a more suitable shelter.  At that point, if you and your clothes are wet or damp, you're going to be at serious risk of hypothermia.  We want to be warm and dry, not warm and wet!  

So, while MPI does make a SPACEŽ Emergency Bag, it is for that reason, I won't use them and don't recommend them.  The SPACEŽ Emergency Bag is essentially a sealed trash bag made out of the same SPACEŽ blanket material.  Kind of like a sleeping bag, or as I like to refer to them as a "body bag," since they also make an excellent bag to put your corpse into as the SAR personnel carry your body out of the woods.  

Respiration: is the last method of heat loss.  Each time you exhale, you are losing heat in the form of heated water vapor.  Other than to stop breathing, you are going to lose some amount of heat via the exhaled water vapor.  The best way to retain as much heat as possible is to cover your mouth and nose with some sort of insulator such as a fleece or wool mask or even a handkerchief will help.

Now we got all that out of the way, here's how I recommend using your SPACEŽ emergency blankets.

Use them to enhance your emergency survival shelter!  I utilize two of them in most of my shelter applications and have 3 or 4 of them in my BOB.  Folded up they are about the size and weight as a pack of cigarettes.  I don't carry a tent, I build field expedient shelters.  All of which depends on the circumstances surrounding me.  In a wooded area, where I may expect to be for only a short time, I can build a quick "lean to" shelter in about an hour using a couple of SPACEŽ emergency blankets to get me through the night.  This structure can be improved upon as time permits the next day or as the days progress if I find I'm going to be there longer, and can end up being a semi-permanent structure.  The same goes for a "debris hut" shelter, although it takes considerably longer than just an hour to get the basic thing going.  More like 4 - 6 hours to get one up, but again, can be improved upon as time or days drag out, in the end becoming a pretty good semi-permanent structure.

If it's already night time when I get stranded or it's raining, I can string a length of paracord between two trees, and throw my SPACEŽ emergency blanket and a Sil Tarp over it ala "pup tent" style, weight down the ends, plug the rear opening up with branches and vegetation and hunker down underneath until morning or the rain stops.  You can throw one of those up in just a few minutes.

So, how exactly do you use the SPACEŽ Emergency Blanket?  And without having the wind rip it to shreds?

Well, what you do is you back it up using a piece of 2mm or 3mm plastic sheeting cut to the same dimensions as the SPACEŽ blanket (56"x84" or 4.5ft x7ft).  So, along with your SPACEŽ emergency blanket, bring a 2 or 3mm plastic drop cloth pre-cut to the same size as the SPACEŽ blanket, and use it as a backing for your SPACEŽ blanket.   It will not become shredded with the rain and wind unless maybe your in gale force winds.   For a basic "lean to," shelter, run a length of paracord, or better yet, if you have the time, lash a 7 ft. long pole made from a tree branch between two trees about 7 feet apart and at about 3 - 3.5 feet above the ground.  You then stretch out the long end of the SPACEŽ emergency blanket with the shiny or silver side pointed towards the ground and attach it to your paracord or ridge beam made from a branch.   Then stake out the ends on the ground in a "lean to" fashion.  Then you take your plastic sheet and place it on top of the Space blanket, secure it to the ridge beam and stake out the other end on the ground in back.  So now you have a two layer lean to with the Space blanket as the inside liner of the shelter and the plastic sheet on the outside.  You should also weight down the edge the entire length with rocks where your shelter meets the ground to keep the wind from blowing in from underneath.  (I have diagrams posted at the bottom of this post)  If you've used a tree branch as your ridge beam, it's always better to improve it by adding tree branches vertically along the back of it and then piling on vegetation to make it a more sturdy shelter.  And if your in very high winds, you'll have to do this to keep it from blowing away.  (you'll need a stronger structure in high winds)  But if you don't have the time, or you only used a length of paracord as the ridge beam, you can use it without the extra structural support and be fine as long as you're not in high winds.  

Next, take your second SPACEŽ emergency blanket, and place it shiny or silver side up and use it as the floor of your lean to shelter.  Then place several inches to a foot of vegetation on top of it as an insulating mattress to sleep on.  (Remember, just laying on top of a SPACEŽ emergency blanket on the bare ground, you'll lose body heat through conduction.)  But with several inches of vegetation as insulation, your radiated body heat will filter through the vegetation and then be reflected back onto you.  Be sure to close off the ends of your lean to shelter with branches and vegetation so you end up with a three sided enclosed "lean to" shelter where your radiated body heat will be reflected back onto you.

Now if you build a small fire a few feet in front of the "lean to" shelter, with a reflecting wall made of small diameter branches to reflect the heat from the fire towards the lean to, you'll be sleeping inside what is essentially a "reflector oven!"  

Below are a few examples of some field expedient shelters from drawings I found on the internet to give you some ideas.  In all those examples, utilize your SPACEŽ emergency blankets to essentially line the ceiling and floor of your shelter.  With a fire out front, again, you'll sleep like a baked potato inside your toaster oven.  As a matter of fact, I've had to get up and go outside and adjust my camp fire because it got too hot inside.   I've used these in 15 - 20 degree weather with winds blowing at 15 mph or more, I've used them in 35 - 40 degree weather with winds of 20 mph and blowing rain and sleet for 2 or 3 days.  I won't say I was real comfortable, but I was toasty warm and able to sleep for a few hours at a time.   Some times you want to keep the opening pretty low to the ground and close off a lot of the front with branches and vegetation depending on the elements and inclement weather.  But you should get a pretty good idea.

In my area, during winter, we rarely get enough snow to build an actual snow cave.  It just doesn't get that deep or drifts high enough.  Plus most areas are wooded enough to build any one of the above shelters.   However, you can build a "snow trench" shelter.  I've included a diagram below so just remember you can use your space blankets inside to line the floor and ceiling.  Again, remember to put several inches of vegetation, or pine baughs to make a mattress or the cold ground will just suck the heat out of you even if you have a space blanket on the ground.   Also you can build a small fire in the head end of the trench in the area not covered by your roof.   You can get an idea in the diagram.

How to use SPACEŽ emergency blankets if you are stranded in your vehicle during a blizzard or winter?

You will need two SPACEŽ emergency blankets, a knife or razor blade, cold weather electrical tape such as Scotch Super 88 (duct tape does not stick worth a damn, if at all, when it's cold the way quality electrical tape does).  You should also carry an alcohol stove for a heat source.  Alcohol is safe inside an enclosed space in the regards that it is clean burning.  It does not emit deadly carbon monoxide (CO).  It does however emit Carbon Dioxide (CO2) in the form of water vapor so be sure to leave a window open an inch or so to vent the water vapor when using your alcohol stove.  If not you'll get an increase in humidity inside making you wet and clammy.

The alcohol stove for this venture is used mainly as a heat source as opposed to cooking food, but even if all you have are a couple of candles, you'll really be glad to have the SPACEŽ emergency blankets to take maximum advantage of whatever heat you generate.  My favorite alcohol stove for in the vehicle is a roll of toilet paper with center card board core removed and then stuffed into a 1 lb. "metal" coffee can to act as a wick.  (boy, good luck finding one of those these days, eh?)  You can also use a smaller can and remove enough toilet paper to get the roll to fit inside the can.  But a 1 lb can and a full roll of TP works best because it will hold a full pint bottle of rubbing alcohol.  Be sure to keep the plastic lid as you'll use it to keep the alcohol from evaporating between burnings.  You can keep the roll of toilet paper inside the can with the lid on stored in your vehicle, but don't add the rubbing alcohol until you are ready to use the stove.  The stove I just described will emit more BTU's than one of those small Trangia or Vargo Ti alcohol stoves which is why I prefer the coffee can stove, but they will certainly work.  Really, the danger of carbon monoxide poisoning is just too great to use anything other than an alcohol stove or a candle as your heat source in my opinion.  

Now take one of your SPACEŽ emergency blankets, and trim it to line the roof of your car.  Start where the dash board meets the bottom edge of your windshield.  Use the electrical tape to tape it up where you need to.  Run it up the windshield and cut slits to fit the corner posts.  You also want to run it along both side windows so you are essentially inside a reflector oven.  You'll need to cut a lot of slits and use plenty of electrical tape but get it as form fitted as possible.  Leave access to be able to crack one of the side windows an inch or so, so that the water vapor from your alcohols stove can vent.  Tape it along the plastic trim along the upper edge of the roof.  When you get past the front seats as you move back. let the rest hang down behind the front seats like a hanging curtain.  No need to waste heat by heating the back of the car if you are going to be hunkered down in the front seats, so close off the back area by hanging what's left of your SPACEŽ emergency blanket behind the seat.

Now use your second SPACEŽ emergency blanket to line the floor and the seats.   You are essentially turning the inside of your car into a reflector oven.  If you have any spare pieces, be sure and cover the dash, glove box and radio areas as well.  

When that is done, take out your alcohol stove, fill it with your bottle of Isopropyl rubbing alcohol and place it on the flat surface of your floor board.  It's good if you have something non-flammable to place under it.  Be sure you have a window cracked to vent and light your stove.  Since you are not sure how long you are going to be there, only burn your stove long enough to get warm and comfortable then extinguish your fire.  Wait until the rim of the can cools and place the plastic lid on it to prevent the rest of the alcohol from evaporating.  Now would be a good time to try and get some rest and sleep.  When you get cold enough you'll wake up, like you do at home if it gets too cold in the house.  When it gets too cold that it becomes uncomfortable, re-light your alcohol stove and heat your toaster oven again.   Repeat as necessary.  I usually carry two bottles of Isopropyl rubbing alcohol on hand so I can recharge my stove if needed, but if used judiciously, one bottle of alcohol can keep you from dying for over a day or two.

Remember, this is a Survival Situation!  This is nothing to play around with...  You are using an open flame in a confined area with lots of flammable material around, and alcohol burns with a nearly invisible flame.  YOU MUST USE AN ABUNDANCE OF CAUTION! You can not afford to be careless.  So if you have small kids, you have to be able to control them.

Also, pick the best space in the vehicle to close off and turn into your reflector oven.  If it's a better area in the back seat instead of the front seat area, then do it in the back seat.   If you have an SUV and you want to close off the back cargo area and make that your toaster oven because of more room to stretch out, then, that's the obvious choice, now isn't it?

So remember boys and girls...  if you use them smartly, SPACEŽ Emergency Blankets can make your survival situation almost down right comfortable, and you now know that there's no reason to just hang it out there and let the wind rip it shreds.  There's also no need to use it in such a way that it ends up being just something for the SAR personnel to wrap your body in.  But for $3 a piece, and about the size and weight of a pack of cigarettes, they are great items to have in your survival kit, BOB or any other kit you have.

Side note:  With today's modern materials, instead of using a 2mm or 3mm plastic sheet to "back-up" my space blankets in shelter building, I now use a 6 ft x 8 ft Sil Tarp.   They are very light weight and much more durable then using a plastic drop cloth.  I also have a 6 ft x 9 ft Sil Poncho which can also be used as a tarp.  The Sil Tarps are not cheap by any means and for years, I used heavy duty 3 mm drop cloths and cut them to fit the size of my space blankets.  Whatever the case, use what works for you.

Side note: Regarding Isopropyl Rubbing Alcohol, most of it these days tends to be watered down cheap stuff, and will say 70% Isopropyl alcohol.  While it will still burn, it's not nearly as efficient or put out as many BTU's as a stronger concentration.   I look for 91% Isopropyl rubbing alcohol.  Caution: Alcohol burns with an almost invisible flame, and is hard to see.  Be extremely careful when using alcohol as fuel for heat.

Side note:  I can also recommend the SPACEŽ Brand All Weather Blanket and the new SPACEŽ Sportsman Hooded Blanket.  They are essentially stadium blankets which are kind of like a tarp.  They are more durable, weigh more (10 oz & 15 oz), and has some slight insulation properties.   They cost more than the $3.00 Original SPACEŽ Emergency Blanket and they only reflect about 80% of radiant heat.  So there's some trade offs, but they have their place.  Of all of MPI's SPACEŽ products, the only one I don't like is that body bag thingy they call an emergency sleeping bag.

I hope this helps people understand how to make a SPACEŽ emergency blanket  work and understand how useful they are in a survival or bug out situation.  The size, weight, and price of them makes them a big value item to have.  I have about a dozen of them.  I keep a couple in each vehicle, I have four of them in my BOB,  I keep a couple in my regular hiking back pack.   I keep one in my pocket survival kit.  They are cheap insurance to have as long as you know how to use them.

A couple of sources for the Original SPACEŽ Brand Emergency Blanket


Survival Resources

Below are some drawings of various "lean to" and other types of field shelters I found on the internet.  I also have a "snow trench" shelter at the end.  You can get some ideas on how to incorporate the use of your SPACEŽ blankets into these shelters to really keep you warm and dry.

(lean to shelter using only space blankets with tarp or plastic sheeting to "back-up" the space blanket)

(poncho pup tent or tarp pup tent.  use space blankets as an inside liner and floor

(one man shelter... don't forget the space blanket.)

(lean to shelter with fire reflector in front.  don't forget to close off those ends and use your space blankets)

(snow trench shelter)
Semper Fi

Offline mohctep

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Re: How To Use A Mylar Space Blanket Correctly!
« Reply #1 on: June 09, 2010, 08:16:48 AM »
Useful information in there-thanks for posting it. :thu:
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Offline NoGoyGunBoy

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Re: How To Use A Mylar Space Blanket Correctly!
« Reply #2 on: June 14, 2010, 06:57:14 PM »
You will need two SPACEŽ emergency blankets, a knife or razor blade, cold weather electrical tape such as Scotch Super 88 (duct tape does not stick worth a damn, if at all, when it's cold the way quality electrical tape does).  You should also carry an alcohol stove for a heat source.  Alcohol is safe inside an enclosed space in the regards that it is clean burning.  It does not emit deadly carbon monoxide (CO).  It does however emit Carbon Dioxide (CO2) in the form of water vapor so be sure to leave a window open an inch or so to vent the water vapor when using your alcohol stove.  If not you'll get an increase in humidity inside making you wet and clammy.

CO2 and water vapor are separate emissions. 
You can wash it down with a cool glass of water, or you can have it inserted rectally--your choice.

But you WILL be taking the Red pill.

Offline Bud Wiser

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Re: How To Use A Mylar Space Blanket Correctly!
« Reply #3 on: June 14, 2010, 09:07:46 PM »

CO2 and water vapor are separate emissions. 

Thanks for pointing that out.  I'm definitely not a chemist!  However because you made that statement, I thought I'd post a little on CO2.

I should have posted that burning an alcohol stove produces CO2 as well as water vapor.

While CO2 can have toxic effects in extremely high concentrations and with prolonged exposure, it is relatively safe in this method of release. 

CO2 is widely used in the Food and Beverage industry to add carbonation to beverages as well as many other uses.  Also, CO2 is not nearly as dangerous as the deadly poisonous gas CO (carbon monoxide) which kills essentially by suffocation. 

Carbon Monoxide (CO) molecules (which is a common gas emitted by the incomplete combustion of a wide variety of fossil and synthetic materials), competes with oxygen (O2) in bonding with the hemoglobin in blood at a rate of over 200 CO (carbon monoxide) molecules for every O2 (oxygen) molecule.   Thus carbon monoxide enriched hemoglobin prevents the oxygen gas exchange in the lungs which is necessary for life, and results in suffocation.  Hemoglobin is the component in blood which carries the oxygen to every cell in the body.   

As you breath in oxygen into the lungs, the oxygen can not attach itself to the hemoglobin because carbon monoxide molecules has already bonded to the hemoglobin and will not allow the hemoglobin to accept the oxygen molecules to bond.  Again, it results in suffocation.

The use of Isopropyl alcohol as a fuel in a stove essentially does not produce the deadly gas carbon monoxide.  Instead it produces carbon dioxide as well as converting the water in the alcohol into water vapor.  The difference which makes carbon dioxide (CO2) safer as a byproduct of combustion is the second oxygen molecule attached to the carbon molecule.

The bottom line is, be sure to vent a window to help release the carbon and water vapor and to assist in keeping the inside of your vehicle dry.

I hope this helps clear things up for anyone who may have been wondering. 
Semper Fi

Offline Hans.Allen

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Re: How To Use A Mylar Space Blanket Correctly!
« Reply #4 on: July 05, 2010, 11:47:57 PM »
Great information, very useful. Thank you!
"...We must all fear evil men. But there is another kind of evil, which we must fear most... and that is the indifference of good men." The Saints