Down Vs. Synthetic

Posted by Ettienne Montzka-Caceres on

When it comes to insulation, down – the fluffy under-feathers from ducks and geese – is the best. Right? Well, actually the best answer is, ‘it depends’. Down is a truly outstanding insulator. Its ability to trap your body heat and keep you warm is virtually unparalleled. (Wool can also muscle in on this debate, but we’ll save that for later.) But down isn’t exactly super useful when it’s wet. In fact, your down jacket looks more like a drowning cat than a gracefully gliding duck when exposed to damp conditions. It’s also a lot more expensive and requires more than just your average dose of TLC to keep it in tip-top form.

So what are the alternatives? Well, there’s that other natural insulator, wool, that we mentioned above. But due to the cost and weight wool is rarely used as a jacket or sleeping bag filler. So instead human beings have tried to recreate down’s amazing air-trapping abilities without any of its drawbacks.

For us at Fjällräven that translates into G-Loft Supreme, developed by Goldeck Textil in Austria. Made from 10% recycled – remember this figure – and 90% super-thin polyester fibres it offers outstanding warming capabilities, even when wet. The fibres work in a similar way to down. They cluster naturally so innately trap air. In this way, they work in a similar way to down feathers. So what makes them different?

Remember that 10% recycled figure? Well, it’s the recycled fibres, which are marginally more rigid than the natural fibres, that ensure G-Loft Supreme has an in-built bounciness. “It’s like memory foam. The molecular structure of G-Loft Supreme means the fibres automatically recover their original shape, even with repeated wear and washing,” says Daniel Holmgren, senior product developer at Fjällräven. Furthermore, unlike down G-Loft Supreme is really quick drying and keeps you warm even when it’s wet. We’ve also managed to get it pretty compressible too, although down still has the edge.

So that’s the science part. But how does this help you make an informed decision? Let us break it down for you.

Down pros:

  • Extremely warm while being exceptionally light (high warmth-to-weight ratio)

  • Very compressible

  • Long lasting

Down cons:

  • When it’s wet it’s virtually useless

  • Takes ages to dry

  • Requires a lot of TLC to wash

  • Expensive

Synthetic (G-Loft Supreme) pros:

  • Warm even when wet

  • Quick drying

  • Easy to take care of and wash

  • Cheaper than down

Synthetic (G-Loft Supreme) cons:

  • It’s pretty bulky and less warm (lower warmth-to-weight ratio than down)

  • Needs replacing sooner than down

So first ask yourself what are kind of activities and adventures are you going to be using the jacket or sleeping bag for? And what is the climate like?

We suggest down for:

  • Very cold but dry situations like ski touring in northern Scandinavia or Canada

  • As a reinforcement layer for evenings around a campfire

  • Winter camping

We suggest synthetic insulation such as G-Loft Supreme for:

  • Cold but active situations like down-hill skiing in the Alps or US

  • Cold, damp winter days in the city or countryside walks

  • Autumn and spring camping

Or do as Daniel does: “If I’m heading up to the top of a mountain in the winter, I will probably wear a thinner synthetically insulated jacket under a shell jacket, and then take a down jacket in my pack that I can pull on if it gets really cold. There are very few jackets that are perfect in all situations.”

 Expedition Down Lite Vest M

Down vest in classic Fjällräven style, a robust reinforcement garment for cold days.


Keb Touring Down Jacket W


Light, pliant down jacket for extra warmth on winter treks.

Text: Sarah Benton

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