THE LOWDOWN ON… DOWN

What is it?

Like posh duvets, some insulated jackets contain duck or goose down. Young birds are coated in these fine, fluffy feathers, which later form an insulating layer between the skin and oily contour feathers of adult birds. Its function is the same in a jacket. Stuffed into baffles made from a shell fabric, down filaments form tiny air pockets, which trap body heat. Aside from being an excellent insulator, down is also very springy. After being compressed for short periods, a shake restores its ‘loft’.

What is fill power?

The quantity of down used in a jacket (measured in grams) is usually listed in a jacket’s specs. But more doesn’t necessarily mean warmer. The other metric to look for is fill power. This tells you how fluffy the down is and thus how well it insulates. The number listed (typically between 400 and 800) is the space one ounce of down will occupy in cubic inches. Pricier, higher loft down, with a higher warmth-to-weight ratio is separated from poorer quality feathers in an air chamber during processing. Let’s suppose a jacket contains 200g of 800 fill power down. It should be puffier, and so warmer, than a jacket with an equal quantity of lower quality feathers.

The ethical question

There are various alternatives to down. Most are man-made (usually spun from raw or recycled polyester) and mimic its springy, filament structure. Often they’re cheaper, and the best synthetics (like Primaloft Thermoplume) can match the lofting power of the lower quality real stuff. Weight-for-weight, down remains the warmest option however. How then can you be sure it comes from a high welfare source? Reputable brands strive to ensure the down they use can be traced to poultry that have not been subjected to any unnecessary harm, or cruel practices such as live-plucking. The industry benchmark is the Responsible Down Standard.

All RDS-certified brands are listed at: responsibledown.org

More insulated jackets overleaf…