Monday, August 9, 2010
Myth of the Mylar Space blanket….
Was out hiking the other evening with some friends who did not seem prepared for any type of adventure, even a couple of miles into the front-country. They each carried a small "Camelbak" its free pocket stuffed with a few energy bars and two Emergency Mylar Space blankets. I inquired, “what will you do if an emergency occurs”. Each of them referred to their "space blanket" and cell phones as “survival” tools.
I have heard this claim many times before, "a space blanket provides an adequate shelter and can keep one comfortable on an unexpected night out". I have always said “the term space blanket is a falsehood; the thin plastic sheet is neither a miracle material nor a blanket”. Don’t believe the marketing claims!
By definition: "Blankets" trap heat in insulating pockets of dead air space, the thicker the insulation the higher the heat retention value. Blankets do not add heat, they simply trap it.
A thin plastic sheet has no insulating properties; the plastic barrier immediately becomes as cold as the snow, rock or cool wind and will immediately conduct that cold through wet clothing to the body, possibly effecting your core body temperature. A space blanket is not a blanket, nor an effective barrier between you and the environment.
While the Mylar Space blanket is not completely useless, with a little improvisation it can be RE-purposed to meet the needs of many a survivor:
• The aluminized material does in fact reflect radiant heat, just not body heat, used behind a fire or in the rear of a shelter as a heat reflector, can increase shelter temps dramatically. Also effective in providing shade in a desert environment.
• Can be worn under clothing as an effective “vapor barrier”, reducing convective heat loss.
• Aluminized Mylar material is translucent, can be worn over face and eyes as emergency sunglasses, reducing sun exposure and possible sun or snow blindness.
• Opened, the reflective surface makes an excellent rescue signal. Waved as a flag or beach towel in the sun, sends off a large reflection with the effect of a huge broken mirror.
• The polyester material the aluminum is bound to can be: used as a fire starter, cut into strips and twisted into cordage and used in a depression to collect, store and boil water w/ hot stones.
• When enclosed in the material, it is extremely noisy, possibly drowning out the yells of rescuers or SAR aircraft.
• The fragile state of an opened blanket is evident immediately; a small nick and breeze can result in shreds of Space blanket material. Usually these blankets are made too small in size for an average adult and require both hands to keep in place.
• As stated above, they are technically NOT a “blanket” & are ineffective in capturing, retaining and reflecting body heat.
• While extremely compact and lightweight, opening one can be extremely difficult, especially in any wind or with an injury, getting it back into its previous folded size is a feat for the Gods...
• THE biggest drawback of Mylar Space blankets: they are perishable. Their sensitivity to light and heat can, with time, produce a brittle, unmanageable and flaking state. Most preppers store these in their emergency kits for years, occupying valuable space, and may be unreliable when needed.
"So If I remove the Space blankets from my emergency packs, is there an alternative?"
While lacking the compact nature and light weight of the space blanket, there are a number of effective alternatives. 1) A clear 55 gallon drum liner is perhaps one of the most useful items one can carry. Its possible uses are only limited by your imagination. 2) Adventure Medical's Heatsheet Bivy, a lightweight, durable, immediate shelter. 3) Lastly, lets not forget your #1 line of defense against the elements: Proper Clothing. Dress for the worse, hope for the best.
Stay healthy, mind-body-spirit! -Z