Cuben Fiber / PrimaLoft One - Sleeping Bag

I made this Cuben Fiber / PrimaLoft Sleeping Bag in January 2007. It was one of four different sleeping bags I made to test or compare shell material and different types and brands of insulation.

I am posting this now "not" to feature the Cuben Fiber, but to show one way to go about making your own sleeping bag.

I don't really start with a paper pattern. I make one or more full size sleeping bags out of $1 a yard material until I like the fit. At first these prototype bags are not much more than something that look like a pillow case. When I am happy with the fit of the bag I add any extra items such as a hood or neck yoke then make sort of a paper pattern. I use a wide stitch so I can rip the thread out and reuse the material. Each bag is made to fit me snug. I also don't use a zipper but I do make the opening a bit larger so I can get in and out easy.

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The following was written and posted to BPL.com on 01/22/07.
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Cuben / PrimaLoft One - Sleeping Bag

Something happened this past week to cause me to re-look at some of the gear I planned to use on my up-coming hike. We had (for San Antonio) some very cold weather (down to 26 degrees) complete with a bad ice storm. On the good side it gave me a chance to try out some of my new MYOG stuff in the coldest weather so far this winter.

I was warm enough, but laying in my Bivy while it was raining ice pellets on my small Cuben tarp, gave me some time to re-think some of my gear.

Also last Saturday I received a VaprThrm NTS Shirt, VaprThrm NTS Pants and a new pair of VaprThrm Insulated Socks that I had ordered from RBH Designs.com. Over the last couple of days I have had a chance to wear the VB shirt and pants. I wanted to see at what "High" temperature they become to warm or cause to much sweat for ME to continue wearing them. Both the pants and shirt have the extra venting options. I have been surprised so far at the results. The temperatures for the 2 test have been 40 degrees and a light rain and 56 degrees and more or less clear. MY results might surprise you. The results of wearing the RBH VB shirt and pants are one of the big reasons I am re-thinking my winter gear list.

Back to the Sleeping Bag. I used Cuben fiber for the liner of a new Down quilt I had made. It uses Pertex Quantum for the outer shell. The combination of these two materials has worked well. Using Cuben for both the outer shell and the inter liner was next on my list.

For my first of several Cuben Sleeping Bags I will use two layers of PrimaLoft One (pre-quilted) 1.8 ounce per sq yard insulation. The clo for PrimaLoft One is 0.84 and using two layer will give me a total clo of about 2.54.

I started by making several sleeping bag prototypes until I had one that I liked. This is my final prototype.

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Next I made a full size "card stock paper"pattern.
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With a full size "card stock paper" pattern cutting both the Cuben fiber and the insulation was easy. I expect to start sewing on Tuesday.
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This picture shows how I overlapped the quilt seams.
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I think I can say I am finished with my Cuben - PrimaLoft One / Sleeping Bag.
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The bag is made out of all Cuben Fiber. The bag in its present size is 19.08 ounces. I say present size since when making it I added some extra length to it. When I made my last prototype I lost some of its length. The non-insulated insert for the bottom is tapered and when I sewed it to the rest of the bag the taper pulled in the sides and made it shorter. I added 10 inches to the length just to make sure it wasn't short. The current length is 89 inches. I will decide how long I want it but I am thinking about 80 inches. When I do this I think the weight will go down to 18 ounces or less.

The bag uses two layers of PrimaLoft One (Clo of 0.84) 1.8 ounce per sq yard pre-quilted insulation in the main bag. This gives me a total Clo of 3.02. I made a small hood for the bag that uses 3 layers of the same insulation. I also made a neck yoke and used 4 layers of insulation in it. I have elastic in both the hood and the opening of the bag. The bag is made to slide into. The circumference of the top part of the bag will open to 64 inches. The foot end (if cut at 80") will be 38 inches. The insulation is stabilized to the inter piece of Cuben so the shell has no seam lines to leak.

Yoke
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Hood and Non-Insulated Bottom
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Finished - Sleeping Bag after trying it out.
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"Edited" Rolled up for packing.
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Detail of Neck Yoke and Hood. The Neck Yoke is 4 layers (Clo of 6.04) and the Hood is 3 layers (Clo of 4.53) of PrimaLoft One - 1.8 ounce per sq yard pre-quilted.
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Gardenville, nice work! I've never seen Cuben fiber up close but I remember when you made that bag and wondered how it's performed since? Does the cloth breath? Any condensation issues?

Thanks Dryer for you comments and questions.

1. Does the cloth breath? No, Cuben does not breath, but you can build in ways to vent your Cuben items.

2. Any condensation issues? Almost no, I slept in the bag a number of times with nothing on to see what it would be like. The only condensation was just a very little dampness on my feet and that evaporated very fast when I got out of the bag. It was about like you might expect if you had a VB liner inside your sleeping bag. I have used it on my bed at temperatures up to about 65 degrees to see how it would react at a higher temperature with about the same results. The Cuben bag seem to work best for me if I am wearing silk weight capilene underwear or something about that light. As with any VB item I want to be just on the cool side and I have no problem with condensation. I keep my house heat set at 60 F and when it gets a bit cool the Cuben Bag is the first thing I grab to sleep in. I just don't close it up tight. I made the "slide-in" opening larger to make getting in and out easy and I use that as a vent of sorts to keep from getting to warm.

I have been happy enough with the all Cuben Sleeping Bag that I am planning another version of it that should weigh at or under 16 ounces. The new Cuben bag would not have an insulated hood or yoke. I expect to use an insulation in the 2.5 to 2.6 ounce per square yard range so it will work down to something under 40 degrees "F". The bag would be used as a Spring time or early Fall sleeping bag.

Bill, nice work on the bag, i also recall when you made this.

I wonder if you enlarged the hood part a bit if you could slip an inflated, quart or gallon, ziplock bag under it, but still inside the bag itself for use as a pillow support?

Nice bag...But isn't it crisp and noisy?

Is that a WHOLE roll of cuben you have on your working table? <img src="/forums/images/graemlins/tongue.gif" alt="" /> <img src="/forums/images/graemlins/tongue.gif" alt="" />...

What? You did'nt hear? Bill won the Mega Millions Lottery and bought a roll of Cuben Fiber with the proceeds <img src="/forums/images/graemlins/grin.gif" alt="" />...ok, he had enough change left for some thread <img src="/forums/images/graemlins/smirk.gif" alt="" />

Hi frenchi,

Thanks for you nice comment.

If you want an idea of what Cuben sounds take a piece of old time wax paper and crumple it up. Then smooth it out. Then crumple it up again and do that a few times. Once you have done that 4 or 5 times it will make about the same sound as Cuben.

The roll of Cuben you are asking about is just a big shipping tube with some Cuben rolled up on it. I store it that way and don't remember how much is on the tube. I do keep track of what is left on the tube on the front edge of the end piece. If you buy Cuben Fiber direct from Cuben Tech you have to buy it in 9 yard lengths. That piece may have started out as 9 or 18 yards.

I don't think Cuben Fiber is very loud and not as loud as new silnylon. Yes, I know silnylon also gets softer sounding with a little use.


Earthling,

Thanks for your nice comment also.

I just stuff what ever cloths I am not wearing in my bag liner and use that as a pillow.

Also, you need to stop spreading rumors like this. It was three Mega lotteries.

I know some folks think Cuben Fiber costs a lot but what I make with it is a lot cheaper than if I was buying that item ready made.

Nice bag. The pictures look EXACTLY like the ones on BPL <img src="/forums/images/graemlins/grin.gif" alt="" />.

Thanks for your Clo numbers. They were what I would have asked you, but you beat me to it. <img src="/forums/images/graemlins/wink.gif" alt="" />

How was the ice storm? Was it worse than last year? Last year they closed 1-10 from SA all the way to Kerville. I also had 1-2 inches of solid ice on top of my car. I had to break it off with a hammer. Something that is not expected in south Texas.

The pictures are the same I believe. I think I have a picture of hale hitting my tarp with the bag under it someplace. I could not get in the bag fast enough for the timer on my camera to get me in the bag.

Clo numbers: Clo numbers give me (us) a starting point for how low a temperature a synthetic insulation might be good for. Remember it is a guide such as inches of loft for Down is a guide.

The ice storm here last year (winter 2006-2007) was a bad one. My power was off almost 24 hours. I know some parts of the US have had it much worst but for this part of Texas 24 hours is bad enough. My house got down to about 45 degrees but I just put on some of my home made insulated gear and got out a down quilt that I had made.

This winter season has been very mild compared to last winter season. The little bad weather we have had might better have been called a bit of hale.

Bill, I mentioned the pillow idea from seeing the head of the bag. It appears to have enough room under it for some stuffing <img src="/forums/images/graemlins/smirk.gif" alt="" /> to make a firmer pillow should one be desired.

San Antonio has some wicked cold some years <img src="/forums/images/graemlins/crazy.gif" alt="" /> I recall a few years back being there when the grocery store got blown down <img src="/forums/images/graemlins/shocked.gif" alt="" /> with shppers inside <img src="/forums/images/graemlins/shocked.gif" alt="" /> Not exactly my kind of Blue Light special, but, hey, you get what you can on sale <img src="/forums/images/graemlins/smirk.gif" alt="" />

What exactly are the better properties of Cuben vs silnylon Bill if you care to extoll them?