Adventure Medical Kits Essentials Heatsheets Survival Blanket

It wasn't actually an emergency, it just got much colder than I expected up at Lake Vernon in Yosemite in late May. I woke up at 4am, thoroughly chilled, and realized I already was wearing all the clothing that would be reasonable (skipping damp stuff). I wasn't in any real danger, but had been hoping for a good nights sleep before a long hike the next day.

Eventually I realized I had one of these emergency blankets in my gear, and although I was pretty certain it was a one-use item (more later), I decided I might as well try it -- it would also be good to know what to expect in case of a real emergency.

First, kudos for making this so light that it is almost silly *not* to have something like it in your backcountry kit. And having wandered off the track once in a New Zealand rainforest, I really really really like bright orange and bright shiny reflective surfaces, and this has both. I was able to find my own path back to the main trail that time, but the possibility of attracting a search helicopter's attention became something I've thought seriously about.

But I found two significant negatives:

* If your hands are already shaking due to the cold, simply unfolding this thing will be a problem. It expands to a big sheet, but that means the very thin material is folded so many times that it will take several minutes of careful attention and somewhat delicate handling to get it open.

* My mistake, but I didn't understand "blanket": I was expecting something like a bag. It turns out that is a different product, by the same manufacturer and also available on Amazon: look for "Adventure Medical Heatsheets Emergency Bivvy Orange" -- the "bivvy" means you can climb in directly, or slip your sleeping bag into (or, perhaps if your sleeping bag is wet, this might be better inside the bag?). In both cases, the material doesn't breathe so it will quickly collect condensation, so you'll be damp and uncomfortable but warmer.

There are emergency instructions printed on the orange side, which would mostly just make interesting reading while trying to stay warm. For example, you could use the sheet to make a solar still to gather water, but I suspect the overwhelming majority of people that might want or need something like this are fending off hypothermia, not thirst.

And the only reason you might want to try to reuse this would another night in a different location during the same emergency. I tried folding it up, but the result was at least four times as big as the original (and damp, too, from condensation).

The key problem with a blanket is that you'll want to tuck it in to enclose yourself, but such thin filmy material doesn't tuck well; this stuff is thinner than aluminum foil, but thicker than cling wrap (and stronger than both). And you'll want it under you, since you'll lose heat from that side too -- but if you want it wrapped all around you, why a sheet instead of a bag? The bivvy is twice the price, but I think would be much easier to use (and perhaps reuse, at least judging from the product picture).

The only advantage of the blanket is that it could be wrapped around two people -- but not for overnight, just for an unexpected downpour, as the product photo suggests. Preventing a cold drenching might be all you need, but the biv sack could be easily modified to do the same, whereas this product won't be nearly as good if you have to overnight it.

Recommendation: Get an "Adventure Medical Heatsheets Emergency Bivvy" for everyone in the party instead. Yes, you'll pay more, but don't scrimp on critical emergency gear.

It works best with a friend. We've tried it out, and it would keep you toasty if this blanket was along. The largest problem was how to fold it back into it's little case.

I really like this product. The large size is useful even for one person to use. The material isn't as loud or stiff as a typical 'space blanket' which is a huge benefit. The only drawback is it doesn't seem quite as durable as a traditional space blanket, but it is durable enough.