thin & light insulation question

There will be a primaloft 40g (1.2oz) avalible in August, but I don't know if anybody is going to sell it for MYOG…

Check this thread for more info:
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=12296&disable_pagination=1

100 weight fleece maybe- it would be a tad heavy, but seems to fit the bill. You could also try a layer of nylon with a layer of silk or coolmax sewn to it. 4oz microfiber feels great, but would weigh as much as a 2oz combat quilt.

Tim: I have a cotton (yes, cotton) sleeping bag liner that I used to layer my 40 deg bag last winter. I got through a 7 degree night with the liner, bag, and regular clothes in February. Now, approaching the dog days of Wisconsin, the cotton liner works just fine at night and I don't sleep particularly hot.

maybe the primaloft 1.2 is worth a shot. I can't bring myself to take cotton. I have drilled into my students for years that cotton kills and i would feel like a big fat Judas. Fleece is probably a good option, however i don't think i could bring myself to carry a bag that wasn't as warm as one 3-4 oz lighter. I want to be comfortable when i am hot but i also want to keep it as light as i can.

I really would consider, if i knew how to obtain it, making a bag with 2 layers of scrim inside. I just don't know how to get my hands on that.

Do you think a local craft shop would have some ultra-thin polyester batting? I might check that option out.

Tim

nm

Tim,

You could try polypropylene row cover. I've used it for bug netting, sleeping bag baffles, and a handfull of other things. It comes as light as 0.3 oz/yd (you could use several layers). It's basically the same composition as Thinsulate (very fine, soft spunbonded fibers). I bought a big bolt of it online awhile ago and it came out to 13 cents a yard.

hmm, i'll have to look into that. where can it be found? I am not familiar with what exactly it is.

Just google Agribon, Covertan, Reemay, or "floating row cover." It comes in many different weights. The "Reemay" stuff tends to be heavier (about 0.6 oz minimum) and made of polyester, and the Agribon and Covertan are polypropylene. There are a large number of online suppliers, but most nurseries and garden centers carry it as well.

The polypropylene varieties are just tyvek, but a little fuzzier and much lighter in weight.

I have a 65 degree bag from slumber jack ($45). I don't think it has any insulation, just two layers of fabric. You might want to try no insulation, just two layers of fabric.

i may try that. I am planning a sewn through down bag. Before i baffle it and add down i will sleep under it to see what i think.

i will check out the row cover options too, sounds interesting. Will it be comfortable draped over me?

Very nicely finished quilt you put on gear swap Tim, I'm surprised no-one snapped that up yet. I was fingering some of the very thin insulation referred to above which was wrapped round the statuary in Hampton Court in London in February. Seems like a good option.

i'm surprised that quilt is still around too.

Are you talking about the row cover stuff? Any idea what weight you saw? I know it's a long shot.

Tim

Just got to thinking. If i use the row cover stuff will i need to stabilize it more than on the edges like i do with cliamshield? I guess i could use ray's yarn loops or sew it down on the inside layer only. i just don't like to do that, it doesn't look and feel as nice i think.

Hey Tim,
You should use the prequilt from Thru-hiker.
it has a double scrim and is exactly what you are looking for.

http://thru-hiker.com/materials/insulation.php

no it is much more than i want. I just want the scrim, not the scrim in addition to the insulation. I am looking for a bag for only the warmest sweaty nights.

Tim

Tim,

I second Rog's compliments on your quilt. I was impressed when I saw it.

I found an old photo of a summer sleeping bag (with me in it) that I made using the row cover about four years ago. It was four layers (outside –> inside): aluminized PE (like heatsheets), 0.3 oz row cover, aluminized PE, and another layer of row cover on the inside, against my skin (it's soft). It was fragile but warm (even through some frost and light snow one night on a grass pile without a pad), and it rolled up to about the size of a heineken can.

Polypropylene has both the lowest density and the lowest solid thermal conductivity of any textile fiber, and it's water absorbtion is essentially zero (a little less than polyester and a lot less than nylon). Also, the very tiny fibers in spunbonded polypropylene (less than 1 denier) make for a lot of tiny air spaces, and excellent insulation for the weight. Tensile strength is poor, though, and I've found that it has to be replaced about every year.

i'm going to have to give it a shot. This looks like the perfect option for me.

Tim,
I used this during a 10 adventure race in Utah.
It's right up your alley of what you're looking for and know stronger and lighter as well.

http://www.buckscountyoutfitters.com/store/product/32308/Adventure-Medical-Thermolite-Emergency-Bivy-Sack/

How about just two silk liners , one inside the other ?
Franco

Franco:
You'd need a knife to escape in the morning!

Colin:
I like the heat sheet idea. How was it bonded – spray glue?

Tim:
Don't know the weight, I was going to steal some off one of the statues but my girlfriend shooe'd me away :o)

Aaron,
That is probably a great solution. I just can't bring myself to sleep in a turkey bag, i might bake. I have slept under emergency blankets before and unless this one is totally diff it's not something i would want to do night after night.

Franco,
I'm cool with silk, i just want the smallest amount of loft between the layers to stop heat loss due to wind. I would consider using silk on the liner side.

Rog,
I didn't think that by looking at it on a statue you'd know the weight, but it was worth a shot. Word to the wise. If you let your girlfriend keep you from braking the law in the name of backpacking innovation it will always go down like that. She is winning, but i guess they always do. Sex is so much more fun with a partner.

-Tim

Lol! Well, what can I say. She seems to prefer crawling under my WM ultralite in quilt mode to having a seperate bag, so it's a weight saver too! :-)

Rog,

Agricultural fabrics and films make the best cheap DIY summer sleeping bag materials for orienteering and ultras, I think. The film I used was like a Heatsheet but thinner. It was black on one side and aluminized on the other. I cut the pieces and seamed them in one operation with a hot knife. It was totally waterproof (I inflated it and left it overnight to check). The polypropylene fabric inside wasn't attached to anything. It was just two giant socks made of the PE film and another two made with the polypropylene, all nested together. It was warm but very damp inside by morning.

Tim,

Totally outside the box thought but, you might consider packing a lightweight set of long johns to sleep in. I do this in Florida with no quilt or bag. Usually, I wear 140 to 200 weight merino wool from Icebreaker.

I realize this doesn't provide a lot of temperature control like a quilt but, wool is quite good at providing a wide comfort range just from a material standpoint.

This may not be the lightest option when compared to an ultra-light quilt but, I usually sleep with at least a silk layer inside a quilt or sleeping bag anyway. Also, the long-johns won't run away from you in the middle of the night! :)

i always bring long johns too. I just don't find it very cozy to lay out with nothing over me. This whole attempt is about coziness. There are lots of ways i can slept comfortable in 60*+, but i want to be cozy and happy. Like a fat little elf.

-Tim