Sleeping bag fill - Down or Synthetic?

One of the main components of a sleeping bag, in fact, the main component of a sleeping bag is how it is insulated. You need to know that it is going to do it’s job and keep you adequately warm through the night. So should you choose down or synthetic insulation for your sleeping bag?

What are the differences between down or synthetic insulation?

Down insulation, as I’m sure you know, comes from birds. The best down tends to be from eider duck or geese. White goose down tends to be the most popular down for sleeping bag fill as it gives a good warmth performance for a reasonable price. Down insulation is categorised by the ‘fill power’, this unit is a measurement of the loft, (the fluffiness, ie the amount of space a certain weight of down occupies). The higher the fill power the lighter the sleeping bag for the same warmth rating. This fill power is rated in cubic inches per ounce, so a fill power of 400-450 would be a medium quality bag, ideal for those who may get too hot in a sleeping bag, 500-550 would be good quality and adequate for most people camping out in the UK, ,while a 750+ would be a excellent quality and very warm indeed, perfect for colder excursions.

Are weight and space an issue?

 Down insulation is very light weight and can pack down and compress into a tight space, making it more travel efficient as a down sleeping bag will use less space in a pack, rucksack or duffel bag. With the proper care and attention a down sleeping bag can last a lifetime and maintains the same level of warmth from day one. Down features natural wicking properties, allowing any body moisture to evaporate away from your body for further comfort. Down insulation is the preferred choice for backpackers adventuring in dry climates. On the negative side, down becomes useless if it gets wet and takes a long time to dry. So if your bag gets wet in the night don’t count on leaving it to dry out in the sun at camp while you go on a day hike, chances are it’ll still be wet that night. Down is also difficult to clean as many products can damage it. So as long as you can get your sleeping bag dry cleaned and guarantee it will stay dry on a trip then down insulation is definitely the winning choice. (Having said that, some of the more advanced and expensive bags have treated the down to make it more waterproof so do keep a look out for that).

Synthetic insulation. Essentially, synthetic insulation is a polyester threading that has been shaped and moulded to mimic the lofty clusters of down. The biggest benefit of a synthetic insulated sleeping bag is that it isn’t affected by damp in the same way as real down. A synthetic fill is, at the least, resistant to moisture, while many will actually shed water rather than absorbing it. Synthetic materials will also dry much quicker than a natural insulation making them more convenient in this sense, if your sleeping bag is wet while you’re attempting to pack up camp you can simply lay it in the sun for a while and come back to pack it once everything else is done and it will be dry. Should your sleeping bag get a bit smelly from being damp you can easily machine wash and dry a synthetic sleeping bag with no worries that it will damage its insulation. It is far easier to care for than real down.

Synthetic insulation sleeping bags come in all sorts of varieties that are made up of different blends of fibres and materials and technologies, these include Primaloft®, Polarguard® and Thermolite®.

Lets take a quick look at these, although they all do pretty much the same job:

Primaloft®, one of the highest performing insulations in terms of warmth, water resistance, compressibility and softness.

Polarguard®, good thermal efficiency, doesn't absorb moisture and is breathable, fast drying and long term durability.

Thermolite®, here we have warmth and comfort without weight and great wicking properties.

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Unfortunately, synthetic insulation is not as durable over the years as a down sleeping bag. And generally speaking synthetic fill sleeping bags are heavier to pack than down for the same warmth factor.

Sleeping bag shape - Mummy or Caravan?

Sleeping bags come basically in two different shapes, the caravan and the mummy. The caravan style is like the sleeping bags you’d sleep in as a kid, the long rectangular shaped bags with a zip that runs down the side and across the bottom. These are definitely the most comfortable out of the two shapes as they leave you with plenty of room to move your arms and legs around while you sleep, on average a person will move around forty times in a single night. You can also unzip them to spread them out like a blanket. Rectangles are definitely the best shape for a good sleep, you wouldn’t ever find a mummy shaped bed. But there is no way you’d be warm enough in a caravan bag in low temperatures unless it was packed with so much insulation that you’d have an easier job to take your actual bed.

The more space you allow inside the bag the bulkier and heavier it becomes to carry with you. This is why sleeping bags have been adapted to create the mummy shape. Years ago, Arctic explorers realised that if they cut away the excess of the rectangular sleeping bag, keeping it to the shape of their body, not only would they reduce the pack size and weight but they gained an increased level of warmth. By giving the sleeping bag a closer fit you reduce the amount of space for air to flow through and suck out that precious warmth. Some brands, such as Mountain Equipment have gone a step further and added a foot box with added insulation to their sleeping bag so you can comfortably sleep with your feet in their natural upright position.

Sleeping bags are, without a doubt, an essential piece of equipment and it’s important to make sure that you get the right one for you type of adventures. v-tex fashion provide both Down and Synthetic sleeping bags in a variety of shapes and sizes.