Insul-bright for cozies

[Mario Caceres]

I’m planning to make some cozies for my TI pots and TI mugs using Insul-Bright.  I have done in the past cozies with reflectix, but I want to give Insul-Bright a try (It’s supposed to be less bulky and I should be able to fold the cozy inside the pots/mugs when not in use.  (I have some stack-able pots and mugs that won’t stack when the reflectix cozy is on)

Anybody has any suggestions of what kind of fabric to use for the outside of the Cozy?. Should I use a breathable fabric or non breathable fabric?.  (I lightweight versions of both on hand).

[Ken Thompson]

Would non breathable be easier to clean, stay dry?

[Mario Caceres]

Thanks KT, that makes sense.  Reflectix which is widely used for cozies is also non-breathable material.  On the other hand, I got the idea of using Insul-Bright from old threads in BPL where Sarah Kirkconnell advocated for it’s use.  It seems that she uses cotton for the outside of the Cozies she sells.  I wonder if it has a functional purpose or is just because there may be more aesthetically pleasing options on cotton fabrics (which may be important when you are trying to SELL a product)

[Mark Fowler]

I agree with KT that coated fabric is the way to go.

I have been playing with cozy materials recently and with Insulbrite it seems that you should encase it in fabric – have it as an inner between two sheets of fabric like the filling in a quilt.  In that case you should build it into a close fitting stuff sack for the pot.  I have on my list of things to do to make an insulbrite cozy to see how it performs.  I made my new cozy out of two layers of 2mm closed cell foam.  This provides the same performance as reflectix but with a 15 gram (1/2 oz) saving including 2g saving from a slightly smaller stuff sack (weight for cozy and sack 20g vs 35g for a 900ml pot). I usually keep the cozy inside the stuff sack and fold down the sides when inserting the pot.

 

[Mario Caceres]

Thanks Mark.  Yes, the idea is to encase the insu-bright in lightweight fabric and make it close fitting.  I have sent a private message to Sarah, but being a long weekend she may not reply in the next couple of days.  I think I’m going to go ahead with some silnylon as the encasing fabric.

Good to know your close cell foam cozy is collapsible.  Again that is the main reason I want to try insul-bright.  So I can put it inside of my nesting posts or mugs (when is more than just me on the trail).

I do have a reflectix cozy so I should be able to make a side by side comparison of weights & performance once I finish the insul-bright one.

Cheers

[Mark Fowler]

Mario your post inspired me to do my test with insulbrite.  I lined a close fitting stuff sac with a single layer of insulbrite but not an inner layer of sil-nylon. The test looks at the temperature drop over 10 minutes with 500ml of water starting at 90 deg C. The pot is preheated with boiling water before being filled with 500ml.  The temperature of the water is initially above 90 deg and slowly drops back to my start point ensuring the system is fully warmed up. The stuff sack was tight around the rim of the pot so appreciable exit of heated air is avoided. The insulbrite does not perform quite as well as reflectix or the foam with a 7 deg C drop (Edit – 6.6 deg C drop with a properly made lined stuff sack ) compared to a 5.1 degree drop for the foam or 5.5 degree for reflectix. This difference should have little effect on rehydration in the field but will be exacerbated at temperatures lower than my kitchen (20 deg). The weight of the insulbrite was 15g so the weight of the insulated stuff sack will be intermediate between the foam version and the refectix at about 25g. The insulbrite certainly gives the thinnest cozy and the most flexible. Just remember that with insulbrite it is shiny side in when making your cozies.

For reference a pot with no lid drops 24.3 degrees while a pot with lid drops 11.2 degrees under the same test conditions.

[Bill Giles]

The general reason for using cotton with Insul-bright is high temperatures. Cotton is used for the outer layer of hot pads and protects the Insul-bright.

[Ken Thompson]

Sound reasonable Bill. But, I have a cozy that is nylon that works fine. A 400 degree cookie sheet is one thing. A boiling pot of water is another. So perhaps it really does not matter? IDK

[Mario Caceres]

Mark, good idea to just putting the insul-bright inside a stuff-sack. It was a bit challenging sewing the round bottom of the cozy for an inexperienced sewer like me. However, for durability purposes you probably want to line the inside of the cozy. My results also indicate that the reflectix is slightly better insulator but the difference is very small (see chart below)

Bill, I agree with KT.  The cozy will be at temps below boiling (212F) not subject to oven temps (over 400F). Also for oven mitts you probably don’t want something slippery like silnylon. Cotton gives a nice grip when using it as the outer-shell for oven mitts, etc.  Perhaps one of the benefits of using cotton (or other breathable fabric) is that you can avoid some condensation from the steam inside the pot. But a bit of condensation is OK, as it will quickly dry-out after use.

Anyway, here is my finished Insul-bright Cozy and the reflectix one for comparison.

The construction of these cozies is a bit different, the Insul-bright is basically a tight fitting insulated stuff-sack. (I used 1.1oz silnylon to encase the insul-bright). I also did make a small insulated dish for the top so warm air does not leak (too much) from the closure of the stuffsack. Since warm air goes up so I thought it would be specially important to have more insulation on the top of the pot.

Here another picture with the sides of the cozy folded down. I like to eat straight from the pot when possible, so I would use it like this when eating from the pot.  It keeps your food warm longer and it is easier to hold the pot as a bowl without burning your hands.

My old reflectix cozy is just two opposing cylinders (of slightly different diameter), so in effect there are two layers of insulation on the sidewalls of that cozy.

I also did a performance comparison test, by boiling 2 cups of water, and then taking measurements of the water temp at fixed intervals of time. This is what I got…

Time       No_Cozy     Reflectix    Insul-bright
0 min           212F           212F           212F
10min          190F           199F           198F
20min          173F           190F           188F
30min          161F           181F           178F

weight        0g/ 0 oz     50g /1.7oz   27g/0.9oz

I’m actually impressed how the pot alone (with the lid) did a decent job keeping the temperature of the water, I was expecting a much bigger drop. Of course, this is in my kitchen, so I would assume in the field when you are exposed to breezes and colder temperatures, the benefit of any cozy becomes more evident. This also another reason to use coated fabrics for the cozy as they provide better wind resistance.

And lastly, here is a picture of how you can collapse the insul-bright cozy. (In the palm of my hand I have both the cozy and the top disk).  This is not possible with the reflectix one.

[Bill Giles]

I agree that cotton or Nomex or other fire resistant fabric is probably not necessary for cozies, as long as you know not to try to put anything really hot in it. I think that I might rather use polyester instead of nylon, but it shouldn’t matter that much. I’ve been using foam rubber for my cozies lately.

[Ken Thompson]

Looks and worked good Mario. Nicely done.

[Mario Caceres]

Thanks, hopefully other folks can benefit from this thread.  The insul-bright is very easy to work with and you can buy it at Joann’s Fabrics by the yard.

[Bob Moulder]

Mario, good job on the testing.

I like actual tests because they dispel a lot of myths and demonstrate that sometimes the type of material used doesn’t make a huge difference.

 

[Jennifer Mitol]

OK – stupid question.

the pot is really hot.  It is full of your hot food.  How do you get it IN that stuff sack cozy without a) burning yourself and b) spilling your food?

[Mario Caceres]

Thanks Bob.  That is something i like about BPL too, folks like numbers and hard data.

Jennifer, no stupid question.  There is no difference on how you use the pot cozy out of insul-bright vs the widely used reflectix one.  Yes, you need to be careful when putting the hot pot inside the cozy.  In my trips  I normally carry gloves for cold nights which I also use to handle hot pots.  Otherwise there always some clothing laying around which you can use to grab the hot pot and insert it in the cozy.

Bill Giles said “… I think that I might rather use polyester instead of nylon,”.
Bill could you please elaborate why would you prefer Polyester over Nylon for this application?.  I still have 3 more cozies to make (two mugs and one pot) and I do have some remnants of silpoly 1.1oz and silnylon 1.1 on hand.  I could use either.  I like that silpoly is slightly easier to sew than silnylon, but the silnylon is supposed to have better abrasion resistance? (cozies will be constantly put on top of rocks and with pots/mugs rubbing the fabric every time is inserted / removed, a bit of extra abrasion resistance should be welcomed?.  Somewhere I read that polyester retain odors more than nylon (but I can’t find the link.)

[Bill Giles]

It probably doesn’t make much difference what you use for the outside of the cozy, since it isn’t exposed to the higher temperatures that the inside is. Polyester and nylon are both rated about the same as far as maximum temperature, but I prefer to work with polyester and polyester has better UV ratings. I made an Insul-bright cozy a while back and used some polyester lining material that I had lying around. Insul-Bright is polyester anyway and it seemed like the right choice. I’ve made cozies out of various material and most recently out of aluminum foil coated closed cell foam rubber. I haven’t made up my mind as to which materials I like best.

[Mark Fowler]

Jennifer – you need a pot with a bail handle. Then it just gets lowered into the cozy.  I modded my Evernew ECA265 with stainless steel fishing leader with a saving of 17 grams. You need to be careful that the pot is not too shallow or it becomes unstable.

 

[Nick Smolinske]

I was inspired by this thread and decided to make one for my new Toaks 1.6L pot.  I used 1.6oz argyle-print ripstop from RBTR for the exterior and some black taffeta I had lying around for the interior.  I figured I might as well make it fun to look at . . .

Anyway, I tried the simple stuff sack design but didn’t like how hard it was to load the pot into the cozy, so I played around a bit and camp up with this.  Probably not the lightest solution at 65 grams but it should be pretty functional.  I wanted it to seal up tightly with a drawstring while in my pack, because I got this pot for use with a wood burning stove and I expect the outside to get quite sooty.

So it’s a two-part cozy, one part is an insulated cup that the pot sits into.  The other part is a stuff sack that’s insulated on the bottom and halfway up the sides.  You fold the sides in half and put it upside down on top of the pot when in use as a cozy.  When it comes time to pack it up you unfold the whole thing and you’ve got a stuff sack for the pot.

(pot is upside-down in the above picture)

[Diane Pinkers]

Following the link for InsulBright, there’s a link for InsulShine.  Would using this alleviate the need for another fabric?

[Nick Smolinske]

Diane, insul-shine looks awesome!  Too bad I already made my cozy.  I doubt I’ll have any need to replace it in the next decade or two.  But yeah, it should alleviate the need for another fabric, although it might not work as well for the top of a drawstring stuff sack.  In that case the top of the stuff sack could be made without any insulation at all if you used a separate top cap.

You could also make a simple two-cup overlapping system like the reflectex cozies.  You could sew both sides so that the seams are pointing in at each other and then finish the top with folded over grosgrain ribbon.  That would look quite nice.

[Diane Pinkers]

Well, I’ve got to admit that the argyle is pretty darn spiffy, much more so than the shiny silver! That was the flaw in my plan, the lack of personalization with pretty fabrics.

What is RBTR?

[Bob Moulder]

What is RBTR?

Ripstop by the Roll

[Diane Pinkers]

 

https://ripstopbytheroll.com

Oh, man, that’s a dangerous place! My sewing machine is packed up until we move, but with a paisley like this:

I might have to get me some! I don’t normally care for pink, but that one is awesome!  Only problem is, I’d want to make a cozy for a Toaks 650 set, and a big bold print like that needs a big space to really shine. They also make it in 0.9 MEMBRANE. Down jacket, anyone? Not exactly LNT.

[Nick Smolinske]

Diane,

Yeah, the prints are pretty neat!  As for using it with insul-shine, my guess is that the shiny metallic finish is only on one side.  So you would still want an exterior fabric with it, whether it be paisley or plaid or argyle.  :)  The only thing you’d be missing would be the interior.

[Mario Caceres]

I have no experience with insul-shine but I finally had the chance to test my insul-bright cozies in the field.  They worked really well to keep my food warm in the peruvian andes.  (Ausangate Trek in Cuzco).  It helps to make the cozy not too snug so its easier to put the pot/mug in and out of the cozy.  The disk on top to seal the gap on the stuff suck closure (See pictures above) seems to work well to keep the heat in.

 

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