Boiling water in a mylar bag

I have a question for the prepers.
I know that you can put boling water INTO a mylar bag, as evidenced by the freeze dried trail food.

Can you use a mylar bag to boil water in or over a fire?

It seems chancy to do it with fire. Can you experiment? Mylar isn't especially thermally-conductive, and is highly reflective. I wouldn't anticipate a lot of heat transfer from a fire into the water inside. Hot rocks dropped in should work, but may damage the bag.

I don't know about mylar, but I remember boiling water in a paper cup in science class in High School.

Yes, I recall the same experiment, the problem was that the top of the cup burnt away to the water level. That experiment gave me the idea that a mylar bag might work.

I might have to experiment, but I am sure that others have already tried. Also I don't know how I would suspend it above the fire.

Hot rocks is a possibility, but like AnAppleSnail mentioned, it may damage the bag.

I did a little research.
It appears that it could work.

Ray Bradbury's book Farenheit 451 is 232 C and that is the FLASHPOINT for normal celulose based paper (so it seems).
Also acording to Grafix Plastics, the melting point of mylar and sheet plastics is 254 C

Since water boils at 100 C if I keep the bag high enough out of the fire, with time the water should boil.

According to DuPont, you might be waiting a while. It's not called 'space blanket' for nothing. Most mylar available is aluminized polyethylene, with thermal conductivity of around 0.14 W/m*K. I don't really know how to calculate the rate at which the aluminized surface will pick up heat, but it wouldn't carry it into the water effectively, either. That said, it's surely better than non-boiled-water diarrhea.

I started a little experiment.

I put a quart of water in (of all things) a cheeto's bag.
Using a couple of spring clips I hung it from my gas fired bar-b-que grill's cover, and propped the cover so that it held the bag about an inch above the heat dissapating tile/rocks.

It has been slowing heating, but about 30 minutes into it, I noted small bubbles inside the bag, and there was some steam. I inserted a meat thermometer and it registered 135F.
At 47 minutes, it registered just under 160F
At an hour it registered 169F.
Those temps are certainly hot enough to make it safe for consumption.
It is my understanding that you don't need to BOIL water, but to pasturize it. That will kill all organisims that are harmful to humans.

I pulled this table off of the net, it probably will not present well.

Darn!
Ten minutes later it was at 175 F and the bag had sprung a pin hole leak at the bottom seam.

Ofcourse this was with a very thin bag. I wonder if the results would be better with one designed to hold boiling water to reconstitute a trail meal.

Poppy said:

...It has been slowing heating, but about 30 minutes into it, I noted small bubbles inside the bag, and there was some steam. I inserted a meat thermometer and it registered 135F.
At 47 minutes, it registered just under 160F
At an hour it registered 169F.
Those temps are certainly hot enough to make it safe for consumption.
It is my understanding that you don't need to BOIL water, but to pasturize it. That will kill all organisims that are harmful to humans...

Click to expand...

Soy fat is used as a Pasteurization Indicator in the WAPI (Water Pasteurization Indicator). The fat pellet melts at 69C (156.2F) so it would look like your water was Pasteurized. WAPIs may often be had for under $10 and they are great in emergencies as Pasteurization only requires a third of the energy that sterilization by boiling requires. WAPIs would also make good trade goods.

IIRC Pasteurization doesn't really kill all the bugs. It reduces the viable number of them so one is less likely to get sick. I think the biggest problem with it for use by the masses is that it is a more abstract process which gives no obvious indication upon completion.

On the mylar's reflectivity issue, I was wondering if one could heat water in a turkey basting bag...or a Crock pot liner bag.

A 'Mylar balloon' if hits a high voltage line will explode leaving people without power for at least 12 hours.
A child on our block did this and the explosion was significant.

I understand that you can use a paper cup because the boiling water conducts the heat away, keeping the paper below the burning point. Does the water that soaks into the cup make a difference?

Daniel

Sub_Umbra said:

Soy fat is used as a Pasteurization Indicator in the WAPI (Water Pasteurization Indicator). The fat pellet melts at 69C (156.2F) so it would look like your water was Pasteurized. WAPIs may often be had for under $10 and they are great in emergencies as Pasteurization only requires a third of the energy that sterilization by boiling requires. WAPIs would also make good trade goods.

IIRC Pasteurization doesn't really kill all the bugs. It reduces the viable number of them so one is less likely to get sick. I think the biggest problem with it for use by the masses is that it is a more abstract process which gives no obvious indication upon completion.

On the mylar's reflectivity issue, I was wondering if one could heat water in a turkey basting bag...or a Crock pot liner bag.

Click to expand...

The first time I heard of a WAPI, was when I read Cody Lundin's book, "When All Hell Breaks Loose: Stuff You Need To Survive When Disaster Strikes."

I don't know anything about either of the other two bags you mentioned, I'd be interested in knowing if you find anything out.

I'm putting together one of those Altoids Survival Tins.
A water heating container that would fit is the challenge.
For now, I cut the bottom out of an aluminum foil pan. I cut it into a 8" x 6.5" piece and folded it into a 2"x 3.25" size so it will fit. Unfolded, with the corners tucked in, it should hold about 12 ounces.

I thought that a mylar bag would compress small enough to fit in one, much better than a 1 quart zip lock bag.

I wonder how well a zip lock bag would work?
I wonder if the bag was cradled in a wet cloth, like a bandana, and carried "hobo" style. The wet bandana may evaporate water, but not get hotter than 212F. That temp would protect the plastic, but still allow for the transfer of heat to the water contained within. The bandana may need to be re-wetted a few times. Thoughts?

Poppy said:

...I thought that a mylar bag would compress small enough to fit in one, much better than a 1 quart zip lock bag.

I wonder how well a zip lock bag would work?
I wonder if the bag was cradled in a wet cloth, like a bandana, and carried "hobo" style. The wet bandana may evaporate water, but not get hotter than 212F. That temp would protect the plastic, but still allow for the transfer of heat to the water contained within. The bandana may need to be re-wetted a few times. Thoughts?

Click to expand...

I think the size constraints of an Altoid tin would tend to rule out nearly anything but some kind of iodine tablets for water and unfortunately their proximity would probably wreck half of everything else in the kit.

I have run across many viable, low tech, solar Pasteurization techniques that are cheap and will work over and over again -- but none that will fit into an Altoid tin.

I had two failed experiments with zip lock baggies. They may have been the store brand type, and not as good as a nationally advertized brand.

The first leaked at the seam within ten minutes. It may have started leaking right at the outset and I just missed it, because there was no sign of melting that would account for it to start to split, nor was the bag hot to touch.

The second bag, I hung with a pair of clothes-pin type clamps, to the edge of the cover, of my grill, that was propped open, but partially closed. The bag was about 3/4th full of water, and not supported in any way. An hour into the experiment, the water was only 140F and the back, top, of the bag melted and tore away so that all that was holding the pocket of water was the front half of the bag.

Problems with the experiment's design:
1. the heat was not evenly distributed. The bag of water was heated from below, but the front of the bag was hanging adjacent to the outside ambient air (about 65F) while the back of the bag was in the more enclosed space (like an oven). I don't know??? 300F ??
2. probably cheap plastic bags... better quality should be attempted.

Observation:
1. Just like in the paper cup experiment, (the cup caught on fire and burned down to the water-line), the plastic bag maintained it's integrity where it was in contact with the water it was holding, however, the plastic, not in contact with the water, if not closely monitored, can loose it's integrity.
2. water is heavy and the plastic bag is a little challenged in supporting the water's weight by the lip of the bag with clips.

More experimentation is necessary.
Better quality bags
more even distribution of heat
external support of bags (damp/wet cloth?, sitting in the coals?, lying on a rock, next to the fire?)

Sub_Umbra said:

I think the size constraints of an Altoid tin would tend to rule out nearly anything but some kind of iodine tablets for water and unfortunately their proximity would probably wreck half of everything else in the kit.

I have run across many viable, low tech, solar Pasteurization techniques that are cheap and will work over and over again -- but none that will fit into an Altoid tin.

Click to expand...

I thought I would throw 4-8 of them in the kit, and just wrap them in plastic wrap. Is iodine particularly corrosive?

If so, I could put them into a plastic straw and melt the ends to seal them.

Poppy said:

I thought I would throw 4-8 of them in the kit, and just wrap them in plastic wrap. Is iodine particularly corrosive?...

Click to expand...

Very much so. I had a med kit that I always took overseas with me. It had a Polar Pure water treatment bottle which has re-sublimated iodine as an active ingredient. Though I didn't notice it at first the vapors from the iodine changed the color of the bag, took the plating off of metal instruments and eventually completely ate through the steel cap of a factory sealed backup bottle of iodine pills, which then accellerated the corrosion of everything else...

While on this subject I'll mention another extremely corrosive chemical that preppers may come across sooner or later for treating water. Calcium Hypochlorite (Pool Shock) is very concentrated and is even harder to contain than iodine. Do much research on handling and storage before procurement.

Hmmm.... sealed inside a plastic straw, it is!
Thanks for that note.

I had read that iodine tablets in it's original container are good/effective for 4-5 years, but only 1 year once the container is opened. I bought a package of Coleman purification tablets that had two bottles, one of iodine, and one of a neutralizer, ascorbic acid (takes the iodine taste away). I didn't notice it until after I opened the package, that the rim of the cap of the iodine tablet bottle, was all rusted. The cap was loose.

The pictures of the WAPIs that I found online look like they would be too big to put in an altoid tin.
I'll probably get a little mercury thermometer to put in there, but I discovered a site that sells "camerons temperature poppers" they can be had in different temperatures for example 145F for fish, or 170F for turkey.

Here is an explanation of how they work, with a diagram,
http://home.howstuffworks.com/pop-up-timer1.htm

and a little known fact is that they can be re-set and re-used. :thumbsup:

The next time I get a chicken with one in it, I will have to experiment

I haven't gotten a turkey or chicken popup yet, but I'll make sure that we have an oven roaster chicken for dinner some day soon.

This morning, I put a piece of birthday candle in hot water and it started melting between 150F and 160F. I know that different types of wax will melt at different temps, but with the concept of bringing things that have multiple uses, a small candle can be put into the tin.

It was a two colored candle. Green with white stripes. The white stripes were made with a lower melting point wax than the green core. The white started melting at about 145-150F, and the green at about 160F. I found that interesting, and useful.

I'm not making a SHTF survival, just a (I got lost in the woods, and need to survive for a couple of days until I am found) 2-3 day scenario.

Poppy said:

I have a question for the prepers.
I know that you can put boling water INTO a mylar bag, as evidenced by the freeze dried trail food.

Can you use a mylar bag to boil water in or over a fire?

Click to expand...

open flame is more than 1000c, even if mylar can take 300c it still will melt if touched by flames.