How effective are Cozies?

Well that does it… I'm making a reflectix body suit

Great Data Thanks for taking the time to do that!!!

very interesting discovery man. seems the lid is crucial…

Thanks, it was my pleasure. I really like doing these kinds of reviews. I am working on a review of wood stoves as well. I should probably start a thread to share that progress as well.

I have made a Reflectix vest by just cutting out the pieces in the desired pattern and using duct tape to hold it together.
I've made booties the same way.

Rob, you have fun in your reflectix, I'm going to make a thermos suit of armor!

I was thinking that with the reflectix booty, you could pull your foot out, put your BOB meal in it to re-hydrate, and then it would be nice and toasty when you stick your foot back in. Dual use – LOL

Seriously though, did you have sweating issues with a vapor barrier like that?

No, not really.
You have to pay close attention to your insulation layering with any VBL when doing any activity, or you will sweat alot. So, it takes some getting used to.
The whole key to it is layering, and venting. When you begin to feel like you might break a sweat, you have to get some layers off, or do some venting. Or else cut down on the exertion level. Or all of the above.
But the partial barrier like the vest is pretty open, so it is very forgiving.

I sleep in cold weather with a full vapor barrier layer, including VBL socks and gloves. Total VBL except my neck. Since I'm sleeping, it doesn't cause a sweat if you aren't in too much bag. If you are hot, then you have to partly unzip the bag and vent it every now and then, or you will sweat.
But the advantage is that I never wet-out my down bag, have no condensation worries, and get full loft, and can use a completely waterproof non-breathable bivy sack for weather protection. Protected from moisture on the outside and the inside.
If you sweat in it, it's a little clammy. Not the end of the world. I can live with it for the advantages. And I'm getting pretty good at controlling my layering and venting to keep me from sweating. It takes practice.

Lets start off by explaining that the utterly major source of heat loss from a container of hot water is evaporation – steam. It is WAY above anything else. So the rule is that we always cook with the lid on.

After 10-15 minutes with the lid on and the stove off, I find that the meal is still too hot to be safely eaten. And that is with a Ti pot with lid and a windscreen around the pot on the stove. No insulation.

My conclusion is that I don't need the extra weight of a cozy.

Cheers

Pete, thanks for taking the time to actually measure this, this is exactly what I've seen with my reflectix cozy, and also by the way what a totally non backpacking blogger mentioned re energy savings via cozy cooking, of course, he was talking about real cooking, not rehydrating, and was using much thicker cozies, but it's the idea, keep the heat in and cook with it.

I may use more dehydrated foods than roger does (ie, I dry the cr@p out of my food), but I doubt I could get my stuff cooked just by covering the pot with a lid and leaving at that, oatmeal/ diced dried apples, which I cook only by cozy, it's not rehydrating the oatmeal, ie, it's actually cooking, cooks just enough in 20 minutes to work, just like your numbers show. Doing some yukon golds now, those take at least 20 minutes to get edible, otherwise they are not unlike wood, or softened wood. But 20, 25 minutes in a cozy is just enough to get them edible, and yummy, again, even with them being as finely diced as I make the pieces to make rehydration quicker.

The weight, 1 oz for 900 ml pot or so. Happily, my health has not declined to the degree where these scattered half/ full extra ounces will have any negative impact, in any way, on any experience I ever have. And having fully cooked oatmeal in the am is nice, can't really live without it, so the cozy isn't really extra weight, it weighs about what 15 minutes more alcohol would weigh, so that's a no brainer re actual weight carried for me. Like the cozy so much I made one for my little plastic cup, now my tea stays warm too in the am, that's nice, they really do work.

Now my guess is that reflectix is not at all the ideal matieral re R value or weight to make a cozy out of, but that's another matter, this seems to be good enough, but a 3/16" plastazote like oware sells, which is r 1 and super light, might work better re weight/r value, don't know, that's another question which further testing could show pretty easily, would be interesting to see that too, but the reflectix is fine, seems enough.

Neat – so the answer is "not at all" lol. So, what about freezer bag cooking? I bring the cozie just to make it easier to handle. I resist cooking in a pot anytime possible so I don't have to do dishes. I'd be interested to see if a cozie helps my FBC at all.

Did you look at the numbers? A full cozy helps a lot, his numbers show that clearly, that's exactly the difference I see too, that's why I use it now, it's the only way using alcohol stove is really tolerable imo. Look a the 10, 20, 30 minute temp differences, those are a lot, hard to see how you concluded it does nothing when it clearly does a lot.

The only surprising thing was how much heat was lost via the pot lid with no cozy lid on, but then again, I don't know how tight his cozy was, too many missing things to really fully get a sense.

I'd guess a loose cozy with no lid is not going to do much good at all, since all the heat will go straight up the sides.

There's been lots of articles on freezer bag cooking with cozy, and how to make pouch cozies for freezer bag cooking, just google it, obviously something cooks better at higher heat than lower, especially when the heat is below boiling, so equally obviously a cozy is going to make things cook a bit better, and a lot better over time.

@Roger – that may be true to during the summer, but on cold winter days, it takes very little time for things to cool off. It also allows boil-in-bag meals to re-hydrate in the cozy instead of on top of the stove saving far more fuel than the cozy weighs.

@Keir – I don't understand your question. The whole point of the test was to show how the heat is held in for freezer bag/boil-in-bag meals.

@Harald – I am with you completely. I think they are great for allowing meals to re-hydrate.

Based on your comment I also see that I have the labels backwards on the "w/lid" and "w/cozy" lines. The difference between the two tests are the addition of the lower cozy of reflectix. In both cases the lid was on the container. The "Full" line then adds the cozy lid.

Sorry about the confusion. Hopefully that is clearer in the video setup – although the same mistake exists in the spreadsheet.

Hi Pete,

Let me make sure that I've got this right. The 4 stages for the plastic container and aluminum pot were:

Stage one: bare container, no lid
Stage two: Stage one plus lid
Stage three: Stage two plus lower cozie
Stage four: Stage three plus top cozie

Given that, did you say that the stage two and stage three data is flipped? While adding just the lower cozie may not do much, I can't believe that it makes things worse…

Eric

Eric,

That is the progression. Very well stated.

Those two lines are reversed. The incremental increase by adding the lower cozy is small, but it is an improvement.

Pete

Sorry – I read the table wrong. On second review, I see what you're talking about.

What if we flipped the cozy upside down and put the bottom over the top? Not sure what your cozy is made of but I've always put my bottom on top creating a second lid.

Edit: Disregard, I watched the video. Your cozy looks to cover the entire cannister.

Works great

I would not be without my home made cozies even if they didn't help with using less fuel.
They let you hold a pot or single wall mug without burning your fingers.
They keep the noise of all your metal bits and pieces down in the pack.
They make the amount of soot etc on your pot a non event when packing your gear.
And after all that they make you look like a seriuos type dude to all the section hikers…
:-)

> that may be true to during the summer, but on cold winter days, it takes very little time
> for things to cool off.
Dunno. We have done our share of ski touring, and cooked dinners, and I have never used a cozy. Well, I may have sat my pot inside my bush hat a few times, but not much more than that. Ah – but I do cook inside the vestibule of my snow tent, and I dare say that is sheltered from the wind and warmed up a bit.

Freezer bag cooking – yeah, a cozy might be useful there I guess. Stops conduction out the bottom.

Cheers

I like the data and the thoughtfulness of having gathered it!

From my perspective, generally cooking for more than myself, I find the data on the Fosters can with full cozie-fication great, because that's pretty darn efficient and weighs less than the thermos PLUS whatever I'd heat the water in (thermos, not so good on the stove), so I'm comfortable I could use the pot/can "like a freezer bag", ie to let the food hydrate and cook.

so far, though, I need more food volume, so I use freezer bags or the Mountain House bag itself, and the pouch cozies are key: food is still steaming hot 20+ minutes later when we portion it out to our bowls.

I use a 1.3 liter pot and I am with Roger in that I leave the pot on the windscreen. I have started using a carbon felt hat on top of the lid to keep things a bit warmer. It only weighs 12 grams and it doubles as a hot pad holder. The extra insulation kept water ~5 degrees warmer over 15 minutes. At colder conditions, it should only get better. Best regards – Jon