Has anyone played with a lightweight version in the backwoods? Would a waterbottle sandwhich made of the bottom piece of black silnylon and a top slice of c thru plastic (groundcloth) be the ticket?

I've essentially done that with one of the big Aloksak plastic bags. I just set it on a rock with a black bandanna underneath and it works great. The water can get quite warm and I'm not sure if a standard zip lock could handle the heat. I've then used the water for bathing and cleaning. In the past, I've used the water water for cooking (thus saving fuel) but I'm not sure if that makes sense, since the toxins in plastic increase greatly with heat. I would like to do a little research though, because it is really handy.

For Spring/early Summer hiking, I take a similar approach when day hiking. The difference then is that I'm melting snow (mixed with water) when I hang out at lunch. That way, I don't need a filter.

I did a little research and there is an Aloksak bag called an Oksak (http://tinyurl.com/28nlds) which is food safe for boiling temperatures. It isn't clear how transparent it is though.

Also, Sarah Kirkconell recommends freezer bags and considers them safe. She discusses the issue at the bottom of the page here: http://www.freezerbagcooking.com/gear.htm.

I just thought of something else. If you really don't like the idea of drinking water that has been sitting in warm plastic, you could just wrap saran wrap around a cooking pot. I think that would weigh next to nothing and still do a good job of warming the water and thus saving fuel. The plastic bag technique could still be used for warming water for washing. I think I may try this next time I go out.

Edited by rossbleakney on 03/27/2008 10:02:41 MDT.

I've used this with great success in sunny weather. I painted one half and the bottom of a clear Lexan water bottle with black paint:

One day last July it heated the water up to 180deg F which is good enough for pasteurization.
Lexan is polycarbonate I believe so should not leach many real bad things into the water when heated.

From ScientificAmerican website:

Plastic (Not) Fantastic: Food Containers Leach a Potentially Harmful Chemical

Is bisphenol A, a major ingredient in many plastics, healthy for children and other living things?

By David Biello



Bisphenol A (BPA) is a ubiquitous compound in plastics. First synthesized in 1891, the chemical has become a key building block of plastics from polycarbonate to polyester; in the U.S. alone more than 2.3 billion pounds (1.04 million metric tons) of the stuff is manufactured annually.

.....

BPA is routinely used to line cans to prevent corrosion and food contamination; it also makes plastic cups and baby and other bottles transparent and shatterproof. When the polycarbonate plastics and epoxy resins made from the chemical are exposed to hot liquids, BPA leaches out 55 times faster than it does under normal conditions, according to a new study by Scott Belcher, an endocrine biologist at the University of Cincinnati. "When we added boiling water [to bottles made from polycarbonate] and allowed it to cool, the rate [of leakage] was greatly increased," he says, to a level as high as 32 nanograms per hour.

Are you thinking for drinking or for say a bath? If for scrubbing up, a black trash bag works great for warming up water in the sun!

I was planning to use it to shower etc. That is why I was looking for a way to heat bottles or bladders, so they could be hung and discharge

Kevin: let's experiment. I know you'd get warmer water if one side is transparent and one is black. So get a gallon ziploc bag and paint one side black. When dry, fill with water and leave in the sun with the transparent side up. Take the temperature at different times up to 8 hours or so. A really decent bath can be had at 120 deg but it would be interesting to find out, too, if a gallon of water is enough.

>> BPA leaches out 55 times faster than it does under normal conditions, according to a new study by Scott Belcher, an endocrine biologist at the University of Cincinnati. "When we added boiling water [to bottles made from polycarbonate] and allowed it to cool, the rate [of leakage] was greatly increased," he says, to a level as high as 32 nanograms per hour.

So hot water causes chemicals to leach out of plastic in vanishingly small amounts, rather than infinitely small amounts. Considering the amount of vehicle fumes I breathe every day, I'll take my chances. ;-)

I'll take my chances too. For one thing, the water isn't boiling and probably never will. In Wisconsin in July the hottest I got it was 180 deg. F. Enough for sterilization but not boiling. So maybe I'll use that water 12 times per year: my wife gets thousands of times more bisphenyl A from drinking her bottled water than that.

Rog considering how close you are to France I would think that chemicals from plastic would be a pleasant idea :-)

I love france,,, Geographically speaking ;-)

And after the goats cheese, well, whatever was leaching out of the wrapping isn't going to come through in the taste anyway.