Silk sleeping bag?

[Brad Groves]

Hi! I've been engrossed in all the MYOG threads this week. Inspirational stuff. In one of the 41 pages, Bill had a quilt that was at least partly silk. Out of sheer (sorry, pun intended) curiosity, and a nagging desire to make a completely natural bag, is silk downproof? From the posts I've read, it's plenty light. It works for baffling material… How about for a shell? Thanks.

[Richard Levenberg]

I do UL bike touring and sometimes I have to go to bed sweaty. About two years ago I sewed my self up a silk sack to protect the bag from my smelly self. I also never carry any other shoes other than cycling shoes so my feet get sort of grungy. I made a foot box in the sack to hold my feet but let them breath a little. Since I do warm weather touring I mostly find the 20+ down sleeping bag unnecessary. What I do is use that for a pillow until it gets colder then slip my silk wrapped body inside the bag for later in the night. Ive already been given the go ahead to make a quilt which I might do this winter.

I got undyed silk from an asian shop for pretty cheap. I think the silk was not the lightest because after explaining what I wanted to do they thought the lightest wouldn't stand up well. I'll weigh it and post again after it dries (just got back from a particularly hot and sweaty tour). Not only did I sew a foot box, but I sewed the bottom extra long and left about a foot unsewed at the front, I bundle all my clothes or my bag under the long bottom for a pillow and the open seam makes it easy to get into and very adjustable in terms of how much covers me. I sleep VERY warm and dont like much covering me.

I will say whats difficult about it is that it doesn't drape well. When I throw it into the tent (that's our slightly heavy luxury) it stays all wadded up and its only when I get in that it un-wads.

Oh and I don't think it would hold down well at all.

Update: 189 gms

[Brad Groves]

I've seen a few posts simply as "bump," which I take to mean "Hello, is anyone out there?" And in that light, Bump.

Reading my original post, I could see how someone would think I'm a nincompoop (sp?) for roughly equating baffling material with shell material. No worries. I am well aware of their differences. I have found down comforers online with 700FP and 60% down shells (other 40% of fabric was, ugh…cotton). So what of it? Is there a silk with a dense enough weave? Could it be callenderized? I'm pretty sure I read about some early down bags being made with parachute silk; it might've been Early Winters?

Thanks for the feedback!

[Mark Hurd]

Brad,
Silk will work for the rest of the bag, too. I think Bill F. has used 5 mm or 8 mm silk (mm= momme not millimeters. I'm a little rusty but if I recall you can multiply the momme number by .128 and get oz./sq yd.) Anyway, I found the 5mm Habutai silk to leak down a little so you may want to go to a slightly heavier wt. I'm sure the Bill F. has much better info than this but you will have to dig to find it. Hope that helps a little.
-Mark

[Brad Groves]

Mark, thanks a bunch. That's exactly what I needed (and wanted) to hear. Off to check ThaiSilks to see what's available. But don't let this stop the rest of you from commenting!

Later- Checked out silks, and apparently the different weaves to choose from would be chiffon, taffeta, or habotai/china silk. Seems that the taffetas available are heavier, but I'd think they'd be slicker? And chiffon, chiffon reminds me of lemon pies, but I guess it has the best drape. The Habotai silk seems to be the lightest, I think? 8mm. Any more feedback from you, Mark, or from Bill F. would be greatly appreciated! Which fabric do I use?!

[Mark Hurd]

Brad,

Habotai is what I've used. Chiffon is sheer and not a tight enough weave for down IMHO. Taffeta might also work, but is usually stiffer than the habotai silk.

-Mark

[Brad Groves]

All right! The habotai's even on sale right now! Thanks for your help, Mark.

[Jan Rezac]

I have some experience with silk too. I've made a quilt with synthetic insulation, momentum shell outside and silk lining inside. I'm using it for a year now and I'm happy with it.

I used very thin 5 mm silk from an art supplies store. It looks quite fragile, but it holds well, I haven't had any problem yet.

I haven't tried it, but I think such a thin fabric wouldn't be downproof at all. It weights about 24 g/m^2, the momentum is 36. Such a small weight difference may not justify an experiment with down. You can possibly find heavier silk, but it will be … heavier than the momentum.

Another reason why not to use silk is that it is too breathable – you will loose warm air through the whole surface of the bag. It is the reason why I used momentum for the outer shell.

One more thing you should be aware of is that the silk is not as slippery as lightweight nylons. It depends on what you prefer – move inside the bag or move with it.

Finally, it is not so easy to work with the lightweight silk. For such a simple pattern as a quilt, it is acceptable, but I've made two balaclavas from the same materials and working with the silk was really tedious.

[Brad Groves]

Hi, Jan-

Thanks for your thoughtful remarks. I debated about the silk knowing that it would be clingier, but if for no other reason than the philosophical/ecological reasons, I really want to use all natural materials. I just ordered the silk last night (well, ok, about 2 AM), but got 8mm, which, if Mark's conversion is right (and it seems right), then the 8mm silk weighs about an ounce per yard. I bought 4.5mm silk to use for the baffling only.

I was thinking about some method of callenderizing the silk. First thought was to just use a really hot iron. Then I thought really hot iron followed immediately with a run through my pasta maker, but realized I'd have to cut the silk into strips. Then things escalated–and I realized that the best method available to little ol' me was to go find a road crew and have them run a steam roller over my silk yardage a few times. I figure that if there's any asphalt residue, it'll just act as some bizarre DWR…

[Roger Caffin]

Hi Brad

You can't calenderize silk – it's a natural fibre. You can only do this to the synthetics which melt.

8 mm is going to leak slightly, but mainly the pin feathers rather than the real down clusters. I use it for sleeping bag liners and silk pygamas.

Cheers

[Brad Groves]

Roger, thanks. If I used 12mm silk, it'd come out to about 1.5oz/yd. This project isn't exactly a gram-cracker; would the 12mm be more downproof?

[Roger Caffin]

12 mm silk? Dunno – it would depend on the weave of the silk.

Caution: a silk sleeping bag may last only a few years, after which the silk will start to weaken and rip. We have to replace our silk liners every few years. I would seriously the use of silk here.

12 mm silk at 1.5 oz/yd is getting significantly heavier than Quantum or Momentum. Reality check: wouldn't the bag makers have already thought about using silk if it could work?

Cheers

[Brad Groves]

I don't understand why silk would have durability problems. I mean, most of my experience has been with some of my boxers and a shirt or two. I have several silk long underwear bottoms/tops that I've sweated up pretty heavily for years. All of those are probably a decade old and in great shape. So what gives?

Roger, I suppose a reality check is in order. Regarding manufacturers, though, I'd think they'd be using cuben by now, too. Merino just started coming back a few years ago, perhaps the front of a natural fiber wave. I have heard that silk blends, at least, are being/have been considered for some green design thing for manufacturers through Backpacker. I don't think I have some breakthrough idea here. Just an interest.

What is the difference between my silk underwear lasting for years, but would make a silk sleeping bag disintegrate? Thanks!

[Roger Caffin]

> I don't understand why silk would have durability problems.
Good question. Remember that the silkworm only has to make something which will last until the Pupae hatch out – a few months. Wool has to last the sheep for several years, but no longer. Natural fibres do bio-degrade. Synthetics are engineered to last a LOT longer, and don't bio-degrade.

I think another part of the problem is that 8 mm silk is rather light. Even though we treat our silk liners carefully, they do start to rip after a few years, usually at the seam near the top end. I suspect that your briefs are made of a much heavier fabric than this. Heavier => stronger. And maybe your briefs are not subject to the same tension as you see in a sleeping bag wall when you thrash around at night.

> Green Design
Sorry to be so cynical, but in my view most of this is just a marketing ploy. I spent 27 years in textile research in Australia with wool, and there is no way I would use it for any extreme sport. A LOT of R&D money was spent trying to get it to match the performance of good synthetics, with zero success among athletes who field-tested the ideas. I've tried it extensively in the field too, in the past.

For fashion and comfort at home cotton, wool and silk are great, but compared to modern synthetics they are weak (especially when wet) and wool takes for ever to dry.

I know I cop a bit of flack over my avatar :-) Those pants are Lycra ski-racing pants. I have a matching Lycra ski top. I was wearing them while out ski-touring, and it started to storm – with rain. I got wet. That is not a good idea in the snow! We kept going in the storm – partly to keep warm. When the rain stopped my Lycra started to dry out. It was effectively dry in 15 minutes.
Bottom line: there are many differences between natural fibres and synthetics, and performance athletes don't use natural fibres in their clothing – except maybe thick wool socks where the felting action is useful. But many do wear wool clothing at home or on parade.

However, this is just my experience and opinion, and everyone is free to make their own judgements about what suits them. That's what the Forums chat is about: sharing experiences.

Cheers

[Brad Groves]

As always, thoughtful comments Roger. Maybe natural fibers should be a different thread, although it sounds like you've found no place for them in your outdoor wardrobe. I do a decent bit of stuff "out there," and my personal experience has been that I'd rather wear my merino layers than my synthetic ones under just about any conditions. To me, it just seems like the wool actually does what the synthetics claim to do. For me, far better temperature regulation has been the best feature. Odor resistance better, though still not quite perfect…

As for this bag, the silk already shipped, and I've got 27 ounces of thru-hiker down sitting next to me (I have a vest in the works, too). I'll cogitate upon life another day or two before I start sewing, but I think I'll probably sew it up in silk anyway, and if the thing disintegrates in a few years, I'll just pull the down and put it in a new bag.

Thanks again!

[Brad Groves]

Hi, all-
Just an update on this project. I sewed up a tiny pillow of the 8mm Habotai silk w/the 800FP Thru-Hiker down, and it's just not gonna work. I lost more down out of that tiny pillow in a day than I did in 15 years with my WM Antelope (I just kept crushing the "pillow" in my hands). Realizing that plastics melt and natural fibers don't, I figured it wouldn't hurt to try scorching a silk sample with my iron to see if it affected down-proofness in any way. After making the second pillow, At first I thought it did help. Then it became obvious that there really wasn't any difference. After crushing/"stuffing" the pillows in my hands ten or twenty times, I'd inevitably find 3 to 8 little bits of dandelion puff coming out of the pillow.

Bottom line, I'm pretty disappointed. Any further progress on this bag would have to involve a lot of talk with textiles experts and perhaps manufacturers. I'm sure that there's some way to make silk downproof, but I don't know how or what weave/density/etc that would be.

So I'm looking at Momentum or Cuben now. Cuben strikes my fancy, but we'll have to see. Sigh. There's gotta be a way to make a natural fiber bag, somehow…

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