I've been wanting to make a down sleeping bag (no quilt for me) for some time now (this forum has been very informative). Lack of funds is one reason I haven't made it yet, but I also have some questions that I would like an answer to before I order material.

I want my sleeping bag to be lightweight, so I'm looking at some of the lighter materials. M50/55 is way too expensive for me. From what I've read M90 is a good downproof fabric for an acceptable weight. I was wondering though if there aren't any other 0.9 oz nylons out there that can do the job and may be cheaper? DIY gearsupply/Backwoods Daydreamer used to have some very cheap 0.9 oz nylon, but they don't sell that anymore.

Does anyone know how owfinc tafetta (http://www.owfinc.com/Fabrics/NylonWoven/taffeta.asp) compares to M90? This is currently the only other source for 0.9 oz downproof fabric besides Thru-Hiker, but there have to be more.

Looking at my neo-air and similar mats with reflective materials also got me thinking. Would it be possible to use reflective nylon? I might be able to get by with less down that way and maybe even save some weight. Does anyone have experience with this? I wonder if breathability might become an issue if I use a reflective outer shell with a normal inner shell. What do you think?

Thanks in advance.

Mark

Reflective nylon wouldn't be breathable. Your vapor would pass through your liner and get stuck in your down. This would result in a loss of loft at minimum. Soggy down at worst or over a few nights. It may be good for a VB sleep system, but then again it probably would not feature the best weight:warmth when considering expense versus cuben.

Go with the OWFInc. 0.9 if you want that fabric at a lower price. It's "very similar" to M90. Kinda like how Trader Joe's has "very similar" products to quality brands but at a better price and with a smile. OWare has it too.

Keep in mind that the 0.9oz./yd.^2 is about 1.05oz./yd.^2 finished.

OWare has a calendared 1.1 DWR ripstop for $3 or $4.50 depending on roll width. Those prices are before Dave's quantity discounts of which you'll hit the maximum assuming you're going to order 5 yards. Quantity discounts are nice. So are pleasant attitudes.

I was curious about the cheap 1.1 and emailed Dave at OWare. He replied:

"The fabric is 1.1 oz finished weight (per yard squared). It is a DWR fabric like the Quarktex, but not as hot calendared and made of a heavier 30 denier thread. The Quarktex is a 20 denier thread.

The properties of the two fabrics would be similar with the Quarktex being slighly[sic] lighter, more wind and water repellant."

Looks like the frugal choice especially if you are going to be using the quilt in a bivy or a shelter where wind and potential spray are not as big issues.

Edited by deGuerre on 09/06/2011 13:26:24 MDT.

Mark,
Long ago, Backpacker mag tested bags with reflective liners and concluded that the reflective material must go next to the inner to have any effect.

This may be, as Pilate says, because putting it next to the outer will trap perspiration vapor in the insulation. That also means that by putting it next to the inner, you would be opting for a vapor barrier bag liner, loved by Warmlite fans, but hated by others. Warmer, but steamy.

Or it may be, as BP found, that the liners, even when perforated to pass moisture, don't work unless next to the inner. I'm not even sure they work at all - they were in vogue only for a short time (Yakworks Yaksac), then dropped by most manufacturers.

You can have a breathable reflective liner just by perforating it. Since you wouldn't want to perforate your inner, though, you'd have to add the weight of the liner, not worth it IMO. Would rather add more insulaton, instead. The lightest flexible (non-crackly) reflective material I've seen is the polyethylene-like Heat Sheets, that could be perforated with a meat tenderizer or whatever. The Heat Sheets is around 1 oz/sq/yd. You can get some pretty good additional R value out of Down, PrimaLoft or LiteLoft for an extra 1 oz/sq/yd.

Or you could look into reflective fabric that is vapor permeable. Be careful.
For example, Insultex claimed at one point that it would pass vapor one way (?), but now seems to have given up that claim. But a vapor permeable reflective coating is theoretically possible, so maybe you can find some out there. But looking for only 20-30 denier fabric with it would make it that much harder to find. Although Warmlite sells their fabrics, I'm pretty sure their reflective material is vapor proof, as they use it on VBL bags.

Best of luck.

Thanks. You confirmed what I already suspected. No reflective layer for me.

Pricing of comparable 0.9 oz fabric as of the time of this post:
owfinc.com $10.10/yd (bulk $7.88/yd 20 yd minimuim) colors: black or royal
bivysack.com $14/yd , $11/yd for 3+ yds, $10.50 for 10+ yds colors: black
thru-hiker.com $9.95/yd. colors: black, royal, gray green, slate gray, evergreen, red, coyote, yellow

community reviews of above companies at backpacking light:
owfinc.com (no reviews yet)

bivysack.com (oware): http://www.backpackinglight.com/cgi-bin/backpackinglight/reviews/display_reviews?forum_thread_id=5038&cat=1%20%2D%20COMPANIES%20%28Customer%20Service%29&cid=67

thru-hiker.com : http://www.backpackinglight.com/cgi-bin/backpackinglight/reviews/display_reviews?forum_thread_id=5039&cat=1%20%2D%20COMPANIES%20%28Customer%20Service%29&cid=67

Down bag beta: 1.1 oz downproof and 700fp down will work quite well for a prototype or even a finished product if you're on a budget. Down items tend to bulge between baffles which reduces the dimensions of your item by about 10%. Quilt patterns are more forgiving than sleeping bag patterns because they are open on the bottom; you can validate your bag pattern with an old bedsheet sewn to shape and slept in at home on your bed for a few nights to get the sizing where you want it. #3 coil works in the short run on a bag, but it's difficult to replace a baffled zipper when it fails (and it will eventually)-- #3 vislon tooth or #5 coil is a better choice. Differential cut is hard to pull off but makes a big difference on bags rated to under 32*F.

Paul - aren't you "Ayce" creator of thru-hiker? That's a great site.

Usually thru-hiker.com is more expensive but has better stuff, interesting that M90 is the same price as owfinc.com.

I've ordered a little from thru-hiker and a lot from owfinc and have had good experiences with both.

I've started to experiment with #3 zippers to save weight. It sounds like in your experience they fail after a while. Is this true?

Are coil or toothed zippers better?

I've used #5 zippers a lot and haven't had a problem. Except two way seperating zippers start becoming difficult to start.

Good stuff. DWR is a must IMO.

I bought 25 yards of 1oz ripstop camo for hammocks for $2 per yard, but its not DWR and I dont think it would be downproof. Good for double layer hammocks though.

Hi Jerry- thank you for the kind words. I've read your posts here for many years, and admire your generosity with your time and experience.
AYCE was a trail name I picked up during my first thru-hike in '94 that stands for All You Can Eat. At the time I had just finished a stint in the Peace Corps and frugal was the name of the game, so town stops with AYCE buffets were a real draw.

RE zippers: Like so much lightweight gear, the individual use patterns and preferences trump absolutes concerning which is "best" so take this with a grain of salt. There is almost always a price to be paid when you move to something lighter, and #3 coil is no exception.
That said,I use #3 coil on almost everything because it is the lightest and reasonably durable. They do fail, but for someone who made the item it isn't all that big a deal to replace the zipper. An exception here would be baffled zippers which are difficult to replace, or for gear where a failure on a trip would be a major hassle.
I use #3 vislon tooth on daily use apparel where weight isn't an issue, and on the baffled zippers of my down bags/apparel. I have never had a #3 vislon tooth zipper fail even on items used regularly for many years.

Troy, check out McNett RevivX, available as a wash-in or spray (no affiliation). Quite effective, not expensive.

Thank you, Paul, for the tip about the zippers. Hadn't thought about the relative merits of coil and vislon tooth in a sleeping bag.

Some #3 Vislon tooth was sold to me by Warmlite with the advice that it would be better than coil for a tent fly zipper, in that it would survive icing up better.

Weighed the Vislon, and it is .17 oz per running foot (not counting sliders), compared to .1-.12 oz for the coil. With a difference of .05 oz. per foot for the Vislon, that is a weight penalty of around .3 oz for a 6 foot zipper. Sounds like it would be worth it.

I hadn't given that much thought about the (dis)advantages of different types of zipper yet, so this is very usefull information. The tip about a bag being 10% shorter when filled will also come in handy. I knew it would become shorter when filled, but how much was somewhat of a mystery to me.