I recently found a "used" but mint condition military surplus four-part sleep system. It comes with the green "patrol" bag, the black "intermediate" bag, and the woodland camo Gore-Tex bivvy bag, with a black stuff sack for the lot. I've seen them for anywhere up to $200, so I was pretty happy to get it for $75 delivered.

I've read that if you store synthetic sleeping bags compressed for long periods that the insulation will lose its value. First, is this true? Second, what constitutes "long periods"? I bought this bag primarily to keep in my car during winter months.

It does compress to the point of damage after a few days. I use a bag twice as bîg, It shouldn't compress it too much.

Yes, if you store a sleeping bag compressed, the fibres will lose their loft (ability to expand back to their original shape and create those insulating air pockets). How long is long, well that is a hard question to answer... Depends on the materials, if it continuously compressed or not, how tight it was compressed, etc.

Due to this effect I do not use sleeping bags in any stored kits. It's far to waste full to keep my expensive sleeping bag compressed all the time. For longer periods of storage I would suggest wool or fleece blankets.

Full compression of a bag is not a good practice, which is why many high end bags come with a loose storage sack, as well as a stuff sack, employed when the bag is actually out on a backpack. However, I must say that I stuffed down bags for quite a few years into a fairly compressed storage mode, and never noticed a big difference.

It is always good practice to unstuff the bag well before you will use it, give it a shake or two, and let it expand to its fullest before you jump in.

I use synthetic bags, and generally store them in not very large stuff bags (though not fully compressed). Like hikermor, I have not noticed any significant loss of loft. One does need to open them up a bit before bedtime to let them fluff up, before crawling in.

While it is no doubt better to store them loosely, I think the alleged loss of loft from storing sleeping bags compressed is rather exaggerated, at least with regards to modern synthetic materials.

Hate to say it depends, but it does. Some synthetics and lots of down bags do not reexpand well after long storage compressed. Like hikermor, I have seen some good down bags that come out OK in a few hours. The old GI vacuum packed down bags (for seat pack survival kits) were pretty much worthless when opened (don't ask me how I know, just say I was glad to have an excellent parka that night). I have also had problems with lots of synthetic bags that would not expand well after months to years of compression. The newer Wiggys bags (like yours should be Chaosmagnet) have stayed vacuum packed for several years and came back to 90% within a few hours of opening. Check out the Wiggy's website wiggys.com for more information. (The usual disclamer here, just a very satisfied customer, several times). This is one reason they are the only bags I will use in a stored kit. If practical, I still do not compress the stuffsack if I can help it. In cold climates (not here >-() I carry one in my car in the sack supplied, but I do not compress it.

Respectfully,

Jerry

I agree on the exaggeration with the supposed compression effects of modern synthetic sleeping bags. I have one bag in particular that is only used in the cooler fall months and after being stored moderately stuffed all year,it decompresses quite well.

On the other hand, I have old synthetic winter bag, about 23 years old that is rated to -30C. Nowadays, that bag rarely gets used and does not decompress very well on its own. However 15-20 minutes in a cool clothes dryer, springs it back to its normal loftiness.

I would buy a Wiggy's bag if I could afford it. What I needed was something that would work in a wide range of temperatures and be small enough for my already overstuffed trunk, and $75 was about the maximum I could afford for that.

My camping is with my small children, so it's car camping and not when very cold. The sleeping bags we use for that are accordingly light. The new sleeping bag is intended to put the finishing touches on my "stuck in a snowbank for three days" kit, which is about the worst survivable thing I think is worth planning for when I'm road-tripping. It's meant as a major improvement over the Heatsheets Emergency Bivvy.

Geezer binge alert!

Back in the mid 50s, when I was discovering the outdoors, one of the best high end innovators was Gerry's (Colorado). They mentioned among other things in their catalog that they packed down items for the military, particularly SAC flight crews. I believe they depicted a vacuum packed sleeping bag, put up in the same container that usually contained canned ham.

Is this anything like the item you used, JF?

Synthetics lose loft after the first compressions. After that, they stay pretty stable at the slightly less efficient thickness.

What really kills synthetic bags is drying on hot. They can shrink several inches in length and loft.