Cozies

http://www.trailcooking.com/store/fbc-cozy
I was the one who came up with a fabric version which is not bulky.

https://sites.google.com/site/hobbyhintstricksideas/Home/cozies-kettles-stoves-etc#TOC-Cozies-at-least-my-type-of-cozy-

I've played around with cozies quite a bit. Hope this gives you some ideas.

I did some crude testing of cozy material in my kitchen. I boiled 2C of water on the stove in my pot, then slipped it into a custom-made reflectix cozy, with lid, stuck a candy thermometer in the water and waited an hour. Then repeated the process with a fabric cozy, made of an oven-mitt material that JoAnn fabric calls insul-fleece, double thick.
starting with water at approx 210F (brought to boil on stove and then moved off)
Reflectix- @60 min: ~175F
Fabric- @60min: ~158F

I believe that the reflection does more than the insulation, but it's hard to test non-reflective reflectix to see, I guess I could just get some bubble-wrap and see.

Thinner car-shield stuff should work, I think probably as well as fabric.

If you want to coast-cook things like pasta, I'd do reflectix, if you are trying to not burn your hands, and rehydrate FD food, anything will work.

Insul-Bright is what I use in my cozies. It is thin, light, breathable, washable and it works. You don't need a double layer either.

I bought medium weight brown fleece at Jo Ann Fabrics, made an "envelope" type cozy with Velcro closure and it works great. It's light too.

I made a double-thickness fleece cozy with a top flap that works great. Unfortunately it weighs 3-4 ounces if I recall. I made another out of Climashield scraps and 1.1 ripstop, light but it didn't work as well, although it was a bit cold on that trip. Everyone has their favorite material, not sure what mine is yet…

Hi Erik! There are 3 major modes of heat loss, and silvery-stuff only affects the most insignificant mode. I'm certainly not an expert, but the very best cheap insulators trap air for the insulating effect. Therefore, the thicker, the better.

Windshield shade isn't as good as Reflectix. Reflectix isn't as good as R15 fiberglass batting. But nobody is going to want to carry around fiberglass batting, so Reflectix is a pretty good alternative. I've also used 3mm neoprene – works pretty good.

It is easy to get carried away with the insulation, but when freezer bag cooking, remember that you only have to keep the water above a certain temperature for a certain time based on what you are rehydrating. So if you are trying to make lunch at -20*F @12,000 feet – you need some pretty good insulation. But if you are just making Mac&Cheese in 50*F weather then most anything will work for cozy material. Most noodles have a 5 minute soak time and don't need much of a cozy. Something like real rice has a very long soak time and requires a very good cozy.

The cozies we make weigh about 1.2 ounces. Our lining fabric is why they are so light.

Also, uncooked (raw) rice and pasta are not FBC friendly, no matter how good a cozy is. Precooked and dehydrated is your friend.

My friend knitted a wool cozy for me and I will be testing it this fall in the colder temps. I'm curious how it will be compared to fabric or reflectix.

Currently I use (insert your cringes here – lol) a wide-mouth (32 oz capacity) Nalgene for the 4 of us and I put it inside an Aquatherm from Granite Gear. Works brilliantly. As baby girl gets bigger we may have to migrate to two of them. Considering that water bottle is split between us the weight is negligible.

"The cozies we make weigh about 1.2 ounces. Our lining fabric is why they are so light."
I've been experimenting with FBC cooking rather than a cozy for my 1L pot.
My new quart-bag reflectix cozy weighs 0.9oz. It's a good bit bulkier than the insul-bright one though. If you're hurting for space, reflectix copies are about as thick as a thick magazine, and like 8".5 square. Maybe too big for some.
One thing I like about reflectix is its easy to clean and doesn't hold food smells like fleece. It goes in the bear bag anyway, but I've been known to be a messy eater and don't like crusty potatoes on my cozy. :)

Relectix ones do get smelly – they can get steamy while the food rehydrates inside – no matter what cozy a person uses it should be bagged or put in a canister at night. You can clean them by washing off where with fabric ones you can machine wash them after each trip (we don't use fleece).