Down or Synthetic. Which Insulation to Choose? A Quick Guide

Deciding between a down or synthetic fill for a garment or sleeping bag can be confusing. Although we have previously dealt with the subject, we compiled a series of questions and answers to help you make the right choice.

Down or synthetic insulation for the cold? Photo Rab

What are the common features of these fills?

Both down and synthetic fiber function in the same way. They are both lightweight and have a hollow core that traps air which is warmed by body heat. This creates a layer of warm air that provides thermal comfort in cold situations.

The materials are also highly compressible so that the garment or sleeping bag takes up little space in your pack.

What qualities of insulation are there?

The different qualities of down are fairly easy to understand, but synthetic fibers are more confusing. The quality of the down is indicated by the Fill Power (FP, capacity to expand) and it usually ranges between 600 and 800 cuin, although some are 900 and even 1000 cuin.

With synthetic fiber, the data is offered in clo units by weight and surface that usually range between 0.7 and 1.3 clo/oz/yd2(you can read about it in this article) but not all manufacturers offer the same data and the large number of fiber manufacturers; Primaloft, Thinsulate and Thermoball, etc. make comparison difficult.

Which is warmer?

Although we have seen great advances in recent years, a synthetic alternative to feather down, able to offer the same weight efficiency / expansion capacity, has yet to be seen. The compression capacity of the feather is also significantly higher.

Comparing the same, fully expanded fill weight, in a dry climate, feather down offers greater warmth.

Which is more durable?

Down insulation does not retain a stable structure, so it has to be stitched into compartments, (baffles), to avoid it accumulating in one place and generating cold spots. For the same reason, if the outer fabric is slightly damaged the down has a high tendency to escape.

Synthetic fiber retains a stable structure regardless of the position of the garment or friction caused by use.

Which works best in wet conditions?

Down is hydrophilic, so it absorbs water very easily and this causes it to lump together and it is unable to expand and trap warm air. To solve this issue, more and more down garments feature water-repellent treatments.

Synthetic fibers have the advantage of remaining warm even when wet because polyester is a very hydrophobic material. In wet weather conditions or if perspiration is an issue, synthetic fibers will work better.

Which works better with a backpack or harness?

The compression capacity of down means it packs small and light in your pack, but this means it is also easily compressed by other gear, such as a backpack or harness, which inhibit its ability to expand.

Synthetic fiber is able to withstand the pressure caused by these items and the insulation structure is not affected allowing it to maintain its insulating properties.

To improve insulation efficiency, some technical down jackets are designed with mapping technology, which uses synthetic insulation in the areas prone to pressure such as shoulders, waist and back and down for the other areas.

If a down garment is regularly worn with items that compress the down, synthetic insulation will be a better choice as it provides greater thermal efficiency.

Which one is more environmentally friendly?

Down is obtained from the chest and belly of geese or ducks. European regulations ban live plucking of down. Some brands, however, use down obtained from outside Europe, where live plucking is permitted, but these brands are not sold at Barrabes. You can read this article if you are interested in finding out about sustainability mountain equipment certification.

Synthetic fiber is obtained from polyester, which often comes from recycled materials. In the manufacturing process of certain fills, they even manage to reduce the emission of CO2 into the atmosphere, eliminating the need for industrial ovens for the thermal bonding process.

Which is easier to maintain?

The animal origin of down along with moisture absorption and its susceptibility to deterioration mean these garments require a certain amount of care, which consists of methodical washing, rinsing and, above all, drying.

With synthetic fiber garments and bags, it is usually enough to use just a delicate cycle on the washing machine to keep your equipment in good condition.

To Summarize

Down fill insulation is preferable if your priority is weight and thermal insulation performance.
Synthetic fiber insulation is a preferable choice if, in addition to insulation, you need a durable and easy-care garment, which is efficient when compressed, maintains warmth capacity in humid conditions and is of non-animal origin.