Goretex and Dryloft is useful under very limited conditions. First I know of no bag that is seam sealed. So water can leak in at the seams. Second, Goretex will tend to let water vapor go from a high humidity/high temperature place to a low humidity/low temperature place. If you perspire, or the bag gets wet, and it is raining outside, no humidity will get out of the bag. Water vapor will tend to condense on the inside of the Goretex outer cover, because it is very cold relative to the inside of the bag. If it is cold, the water will freeze somewhere inside the bag. It is very down-proof, and it does stop wind very well however. If water does get inside a Goretex sleeping bag, it is difficult to remove. The best bet is to turn the bag inside-out, and wait for the water to evaporate.
Most sleeping bags are made of highly compressible materials. This is great because you can pack up the bag in little space. Unfortunately when you lie down inside the bag, your weight compresses the highly compressible material, leaving very little space between you and the ground. There are two problems with this. The first is it isn't very comfortable. The second is there is very little insulation between you and the cold ground. One may wonder why bags have any insulation on the bottom because of this. Perhaps the designer thought that people are weightless? It boggles my mind. Some winter bags put 60% of the insulation on the top, and 40% on the bottom. So only 40% of the insulation goes to waste. Some bag makers have different amounts on the top and bottom, and say you can reverse the top and bottom depending on the temperature. A few years ago Marmot sold a pack which had insulation on the top and had a built in pad on the bottom. It was a very clever idea, so they stopped doing it.
The common solution to this problem is a sleeping bag pad. Pads are made of a variety of materials, but basically there is foam which is cheap and hard to compress and very robust, and there is air mattresses (which have foam inside) which are expensive and easy to compress, and much less robust. You are supposed to put the sleeping bag on top of the pad and sleep. In my experience the biggest problem is I tend to roll around a bit during the night, and I usually roll off the pad. Another problem is that the pad is typically one inch thick, which is much less insulation that a sleeping bad. So if it is really cold outside, you will need a pad thicker than one inch. Some hardy rock climbers sleep on their rope. This is great as you are already carrying the rope. It isn't very comfortable however. Another solution is to pile up clothing and the like and sleep on it. In an emergency, you can pile up debris like pine needles. In the snow or rocky terrain, there is no debris, so you will need some other solution.
I would ignore the new synthetics. At best they are as compressible as 550 down, cheaper, and don't last as long. Some people say they are warm when wet. They do not loose their loft when wet as much as down does, but they loose virtually all of their insulation ability (as does down). It is not clear if they dry faster than down, but might appear to, since they loft more when wet. I wore out the synthetic bag in about 50 nights of use (they loft went down by over 50%). I wore out a cheap down bag in about 200 nights of use, over a 10 years period by blowing out several seams. The down bag still had roughly 70% of its loft left.
In my opinion, the best bag is made by Stephenson Warmlite Equipment Inc. in Gilford, NH. I have one. It is completely unlike any bag you have seen.
Let me describe it. There are two tops, a thick one, and a thin one. They can be used together or separately. The thin one is good down to about 25F. The thick one is good down to about 0F. Both are good down to between -45F and -80F.
There are three zippers. One on each side and one for the feet. There are two separate tracks for zippers. The thick top has two tracks of zippers. The thin top has one track, and Stephenson says to use the inner track for it. I prefer using the outer zipper since it provides more insulation around the perimeter, though less insulation around the head, as it makes less of a hood on the outer zipper track. A friend had one made with an extended inner zipper on the bottom as well as an extended zipper on the thin top. This makes a nice hood with the thin top. I wish Stephenson would make all their bags like this. If you use both tops, the thin top goes on the outside, using the outer tracks, and the thick one goes on the inside, using the inner tracks.
The bottom has a (removable) built in down-air-mattress (DAM), or a 2 inch thick piece of open cell foam. I have both. The DAM is very light, compressible, and warm. In a conventional bag, the insulation on the bottom is compressed by body weight, and next-to-useless. The bottom insulation also adds weight, bulk and cost. With the DAM, you get useful insulation. With a conventional bag, you can roll around in it, which makes the bag roll around. With an integrated mattress, the top stays on the top. The North Face (TNF) had a slip for a thermarest in some of their bags several years ago.
Rolling around on down turns it into little pieces of expensive string. It damages the down severely. It is also extra weight to carry, as the compressed down makes poor insulation.
The Stephenson bag has a built in vapor barrier liner (VBL). This keeps your insensible sweat from soaking the insulation of the bag. It also keeps you much warmer, because you don't sweat. I was wondering how well this worked, and so I asked a friend of mine. He said 'good for below freezing, uncomfortable otherwise.' I decided to make a VBL out of Stephenson fabric to test the idea. Their fabric is called 'fuzzy stuff'. It is a knit nylon laminated to a plastic film. I made the VBL and placed it inside one of my normal sleeping bags. It worked very well. No comfort problem, except that it would get twisted up as I rolled over. Also when I overheated, it was difficult to cool off in a controllable manner, as it was sewn on all sides except the top. I was warmer, the insulation was dry. So I bought a Stephenson bag.
One advantage of the Stephenson bag is that you notice overheating, and correct it by adjusting the bag. In a normal bag, you don't notice it much, and the insulation gets wet, heavy, and you loose more water.
The bag is available with several options. Any color, or colors you want, any girth (with 5 inch quantization). Any length. They charge by girth, length, and other options. Stephenson uses the best down available. Unweighted it has a loft over 1000 ci/oz. Weighted it is 825 ci/oz (as I recall). The down quality varies a bit, depending on their batch, so they fill the bag by loft, rather than by weight. The bag is made with 1.1 oz ripstop nylon, and sewn with nylon thread. Nylon thread is the best stuff around for sewing nylon fabric. They have a catalog for $1, and a video tape for $10. There are two versions of the tape, the naturalist version, and the censored version.
I have been cold in normal bags that were rated for very low temperatures. I have never been cold in the Stephenson bag. I used to soak bags insulation with my sweat. The Stephenson bag has stayed dry. I use it about 30 times a year.
Now the bad news. It is expensive. Mine was $685. That was for a 70 inch girth bag, 6 feet long. But they do last a long time. I have a friend that uses his more than I do, and he has two bags and two tents from Stephenson that are over 35 years old, going strong.
Weight: 70 inch girth bag, 6'9" long thin top 21 oz, thick top 34 oz, bottom with down air mattress (DAM) 60 oz. add 7 oz for the vap-r-soft inside of the tops, so the total weight is 127 oz, which is 7 lbs 10 oz.
The bag also fits in a stuff sack 10 inches diameter, 24 inch long. This is with both tops. With only one top, it is more compressible. You can compress it a bit, but Stephenson says for maximum down life, roll the bag, then put it in the sack. This will equalize the compression of the down. The amount of space is less than a winter bag and pad. The bag is also very roomy inside. Much more than any other bag that I have used.
This is a bit bulky, buy not as bulky as a conventional sleeping bag and a very comfortable pad. The only pad that I have used that comes close to the comfort is the Thermarest Camp Rest Deluxe. The DAM is much lighter and compresses better than the Camp Rest Deluxe. It is bulkier than a good conventional down bag, and a thin pad such as the Thermarest UltraLight. I would rather have a good nights sleep, and a thick, warm, comfortable pad. Since I backpack alot in the desert, the Stephenson bag weighs less than a conventional setup plus one liter of water, which I save in using the vapor barrier liner in the bag.
I have now used the bag under varying conditions for 3 years. I have use it over 100 times, including 2 weeks straight in Fairbanks in March. It was -17 at night. I was warm with both tops. I did put a pile sweater under my butt under the bag, as there was less insulating space, since my weight was concentrated there. I have also used it in conditions as warm as 60F. It works well under all temperature ranges that I have used it. Overall the bag has performed well, but I had a few problems. The Velcro on the collar had begun to unravel. The stitching holding it on is fine, but the Velcro itself has begun unraveling. One of baffle stitches on the thin top has begun unraveling. I sent the bag back, and these were repaired at no charge.
On the other hand, there is what I consider a more serious problem. The vap-r-soft is 1 layer of porous nylon, and several layers of aluminized polyethylene and nylon mesh. This was an option that some felt was more comfortable than the aluminized non-porous nylon. I got this option, since I had not seen a bag beforehand, and I decided to try it out. In several places on both of my tops, the aluminized polyethylene has ripped along the baffle seams. This is evident by more moisture on the outside of the bag (as the polyethylene is the vapor barrier), and by seeing much more light transmitted through the bag where the aluminizing isn't blocking the light. In one spot, the vap-r-soft appears to be ripping at the sine wave stitching used to hold the various layers together.
I got my hands on some var-r-soft material from Stephenson, and I pulled on it in various directions to see how strong it is. I now believe that the base material is plenty strong, but that the baffle seams stitching weakened it in my bag enough to fail at the baffle seams. Or perhaps the particular batch of var-r-soft material I have is substandard.
I returned the bag to be repaired with this problem as well as the two above problems. Jack examined the bag and said that only a large diagonal force could cause the film to break, such as a washing machine. I told him that I had treated the bag well, and had not washed it, nor subjected it to large diagonal forces. He did not want to repair or replace the tops. We discussed the possibility of covering the inside with the normal aluminized coated nylon. He did not want to do this even though he would be charging me for this. We had agreed to this by phone before I sent the bag in, but once it was there, they decided it would be a bad idea, and were supposed to contact me to discuss it. They never called, nor wrote to me. After 1 month, I called and found out they were waiting to hear from me about this. Jack said they only sold the vap-r-soft to deal with people that were leery of the coated fabric, and that it was less durable than the coated fabric, as well as heavier and more expensive. I did not know this beforehand. Jack did say that the aluminized coating wears off of the coated fabric.
A friend got a Stephenson bag very similar to mine after seeing mine. He now has a rip like mine at the top of both of his tops. I believe it is only a matter of time until he has more rips like I do. He believes that his rips are a manufacturing problem, specific to the top of the bag. The baffle stitching looks different on his bag, and on my bag, as the stitches are visible on my bag, but not on his bag. I am not sure if we have a defective batch of vap-r-soft (the bags were purchased over a year apart), or if it is a poor design, or poor sewing. I do know that the vapor barrier properties have been compromised, and that the bag is much moister in the morning, which is undesirable, because I like to wake up, and roll up the bag, and hike without having to wait for the bag to dry. I question the long term life of my tops. I cannot recommend the vap-r-soft material at this time. A friend got the coated nylon after using my bag for 2 nights, and says he is very happy with it.
I am dismayed that Jack is uninterested in fixing my bag. He does not consider it to be a significant problem, though I do. He says that only distilled water from insensible sweat will go through the bag, and this will not harm the down. I don't want any water going through my down. If vapor barrier is so important for sleeping bags, as he and I believe, then why should he be satisfied with my bag with its compromised vapor barrier? I have only used the thick top for 10-15 nights. For it to have developed 3 or 4 significant internal rips, I can only consider it to be defective. His catalog states "We'll fix any defects in construction as best we can at any time, but "cosmetic" flaws aren't considered defects after 30 days!". Perhaps he considers this a cosmetic flaw, or perhaps he considers it not to be a defect in construction. Perhaps I have abused my bag, or he believes that I did. I feel that I should be given the benefit of the doubt. Jack said that large diagonal loads could rip the aluminized layers of the vap-r-soft, but after playing with the vap-r-soft, I think that the rest of the bag would really be damaged severely before that stuff lets go. Needless to say, I subjected my bag to no large diagonal loads. I am also dismayed by their general customer relations, since they did not contact me, as they were supposed to. I sent my address, home phone, and work phone. I also ordered two spare pole segments for my tents, one arrived broken, and the other one was improperly bent. They are sending out another two pole segments, and apologized, saying they must of grabbed one from the defective pile. I have had better dealings with many backpacking companies including The North Face, Sierra Designs, Marmot, Kelty, Montbell, REI, Patagonia, and Black Diamond.
Some people have asked me what happened to my sleeping bag. I ended up buying another Warmlite sleeping bag on ebay. It had the simple coated nylon interior, which works very well. I decided I really wanted my bag to work properly. I contacted Warmlite, and told them I wanted the uncoated nylon interior tops replaced with silicone coated nylon material. They told me this would cost roughly $100 (I don't remember the exact amount). I sent in my tops. They cut the uncoated nylon away, and sewed in silicone coated nylon. This way, the bags vapor barrier is intact. Of course, when the uncoated nylon layer was removed, the damage to the vap-r-soft material must of been clearly visible. It would have been ideal if they had admitted it was defective and not charged me, but I did agree to pay for the repair.
I store my two bags unrolled. I also store the down-air-mattress inflated, as it has down inside of it, and down is happiest when uncompressed. I noticed that the new sleeping bag down-air-mattress stayed fully inflated, but my older down-air-mattress was losing air. I thought the valve might be leaking, and I send it in for repair. It turned out the valve was old but worked fine. The problem was all of the seams where the baffles were sewn were leaking. They charged me about $30 or $50 (I don't remember the exact amount) to update the valve and seal all of the seams. This is a major amount of work, as there are seams roughly every 5 inches all along the down-air-mattress. They did a good job, and the mattress no longer leaks. I have a friend with a similar aged sleeping bag that also needed the procedure done to deal with leaks. I suspect that the older mattresses weren't made very well sealed.
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