The basic questions are always; how warm do you need the bag and how small and light does it need to be? Just like layering with clothing you can build a system for you sleeping bag. I like a light liner that can be used as an ultra light summer bag when it never gets below 50 degrees. Then a zero to 20-degree bag that makes a good spring and fall bag. When you put the two together you get a bag good to below zero. When I go winter camping I also bring a vapor barrier liner that takes up no space but can add a 10 – 20 degrees to your system in the bitter cold of winter. It is basically a bag of waterproof nylon you sleep in with high wicking clothing on. It prevents you losing any heat by evaporation and keeps all the frost out of your bags insulation. I only thing about using a vapor barrier is getting out of it is a bummer in the morning…. lots of smelling steam...especially after a couple of days of continuous use.

I am a big down guy; it works great, is very compressible, and lasts and lasts. But you have to take care of it. Synthetic bags are tough as nails, are better in wet environments, are easy to wash and care for and are cheaper. Also you better invest in a good sleeping pad if you buy a down bag because all the fill compresses under you and you have little insulation or padding from the bag itself. So basically I would simply recommend a down bags for a mature backpacker who want the small size and weight and knows how to care for it. Synthetic bags are great for kids, scouts, folks that are tough on their stuff, folks in wet climates or want to toss everything in the washer.

All right you can buy a synthetic sleeping bag for under 50 bucks or for hundreds…what's the deal? You can sew some insulation between a couple pieces of nylon or cotton for next to nothing. A rectangular shaped, sewn through sleeping bags are cheap, will work fine but roll up to be the size of a small Toyota. The next type is where they sew half of the fill to the top cover and half of the fill to the liner and stagger the stitch lines so there are no cold spots in the bag….better but still pretty big. Most synthetic sleeping bags that cost over 100 bucks, shingle the fill. Sewing it in the bag like house shingles, overlapping the fill and eliminating any cold spots. This is the lightest and most efficient use of the fill, but is costs much more to construct. Some types of synthetic fill are better at certain things. Polarguard is a continuously spun fiber which makes it almost impossible to tear (they keep hollowing it out in different ways to give more surface area which makes it lighter and warmer, hence 3-d, etc…) Polarguard is tough stuff, does not need to be attached inside the bag much to keep it from tearing. Hollofil is patterned after Caribou hair (which is also hollow) and works great and has a softer feel to it but it is shorter fibers and can be ripped much easier. You will find Hollofil insulation is in bags that are offset stitched to have it sewn to the inner and outer layer for strength. Then there are lots of fills that are more waterproof, or that are completely free floating like in the Wiggy’s bags. Hey that is what the forum is for…send me a question and I will let you know what I think.

Basically, if you buy down you want to get a good bag. I love Western Mountaineering bags. They are expensive but worth every dime (and it will take a few dimes to buy one). You will have it for years. Most of what makes a down bag great is what you don’t see. There are little dividers sewn into the bag to keep the down from shifting. The material that is used for these dividers needs to be quality because if they tear the down will start shifting and you will get big cold spots and you can’t really repair these torn baffles. The quality of the down is important but don’t get confused about the top end down 650+ down is all great. Great down and a poorly constructed bag will give you a poor bag. Spend the money…go-ahead get the Western Mountaineering bag…but get it through me…”buy or die”….