Down or Synthetic?

Fill Type - 
Down or Synthetic?  The first choice you will have to make when choosing a sleeping bag is whether you want the fill to be down or synthetic.  Both of these fills have distinct pros and cons that you need to evaluate when you decide to buy a sleeping bag.

Down has the following going for it:

• Long Lived - it remains effective long beyond the lifetime of any synthetic
• Compressible - down can be compressed down much smaller than synthetic fills
• Warm and Light - Offers the most insulating ability for the weight.

Down also has the following drawbacks:

• Expensive - It is more expensive than synthetic fills, but don't forget about longevity.  Down will far outlast any synthetic fill and will usually pay off in the long run.
• Moisture - If down gets wet, it will lose almost all of its insulating ability and will take a long time to dry.  This is probably the major factor that keeps people from buying a down bag, particularly in the south where we have such humid conditions.

Synthetic Fill is made up of extruded polymers or tiny plastic threads.  In most cases, the threads are really a single. continuous thread.  The filaments are usually hollow to increase their insulating ability and are arranged in baffles which may or may not be overlapped for additional warmth.

Synthetic Fill offers the following advantages:

• Cost - It's less expensive than down, but keep in mind that it is also shorter lived as well.
• Non-allergenic - Some of us are allergic to down, so this can offer an alternative.
• Warm when Wet -  This is possibly its largest advantage over down, and what often tips the scales to someone purchasing a synthetic bag over a down one.  Synthetics also dry quickly compared to down as well. 

Synthetic's silver lining is not without a cloud, however:

• Bulky - Synthetic fills don't compress as well as down does and so are bulkier to carry.
• Heavy - They're also heavier than down for the same amount of insulating ability
• Degradation - Synthetic filaments degrade much quicker than down clusters. 

There are several different types of synthetic fill available, the most popular of which being Polarguard.  You may see other bags offering other fills such as Quallofill or Hollofil.  These are older fills and give less insulation and more weight than the newer fills.  These should only be purchased on the tightest of budgets.  A short description of Polarguard fill types is below.

• Polarguard HV - the HV stands for High Void Triangular shape of the filament's hollow core.  This fill is the generation before Polarguard 3D and is a little heavier.
• Polarguard 3D - Until recently, this is the closest thing to down in the synthetic world right now.  It offers a finer filament, more compressibility, and a softer feel than HV. 
• Polarguard Delta - At the time of this writing, Polarguard Delta is licensed exclusively to The North Face, but expect it to show up in products from other manufacturers as time goes on.  This newest member of the Polarguard family has a larger fiber, a larger air space within the fiber, and thinner walls, resulting in a 10% increase in thermal efficiency over Polarguard 3D.  Will wonders never cease?