What is Down?

Down jackets hanging in store

Outdoor adventurers have a long history of using down insulation – in men’s and women’s jackets, sleeping bags, gloves and hats. Thanks to the little bits that occasionally wiggle out of these warm garments, most people know that down insulation is made of feathers. But what is down – really – and why is it so great? Let us explain.

What is down made of?

While everyone knows that feathers come from birds, it is less commonly understood that all feathers are not created equally. Birds have modified their feathers for all kinds of uses. Think about the different needs of, say, a flightless ostrich, a soaring eagle and a swimming penguin. Depending on how highly modified they are, feathers can have very different appearances.

When you find a feather on the trail or in your yard, you’ve likely found a tail or a flight feather. Hidden and protected under layers of these strong, stiff, waterproof feathers are soft, fluffy feathers meant not for flying but for insulation. These are down feathers. They have soft filaments that radiate from a central point, forming tiny puffballs usually referred to as clusters. The biggest clusters of down are found on the underside of adult ducks and geese.

Down cluster on a dark background

Some people say that goose down is the ultimate in quality. In truth, that accolade goes to a duck. Eider sea ducks, which live along the cold, harsh coasts of North America, Europe and Siberia, produce the highest quality and most expensive down in the world. Generally speaking, though, goose down is better than duck down.

Why Use Down

Down clusters trap air very effectively, which makes down one of the best insulating substances known. The clusters can be compacted without damage, allowing down to be compressed. Being literally a collection of feathers, down is also lightweight. That makes down ideal for backpacking gear:  men’s and women’s jackets, hats, gloves, sleeping bags and other applications for which we want packable, lightweight warmth.

The well-known weakness of down is that it loses its insulating qualities when it gets wet. Wet down is essentially a lump of soggy feathers.

Synthetic Insulation

Gear companies have long sought a synthetic substitute which can insulate and compress as well as down but resist the debilitating effects of water. After years of trying, there are now numerous synthetic insulations on the market for men’s and women’s jackets as well as sleeping bags but none truly match down. Alternatively, some manufacturers turned to protecting down insulation with a layer of waterproof fabric on the exterior of the bag or jacket.

A GamE Changer?

Waterproof protective layers and synthetic insulation are commonly available and effective, but many people felt that using down insulation in wet conditions was an unacceptable risk. A recent ground-breaking development may change that: water resistant down.

Water-resistant down is created by applying a hydrophobic polymer to each individual fiber of every down feather. There are several varieties of water resistant down on the market and they differ in the specifics of their promises, but the take-home message is the same: hydrophobic down resists the insidious effects of rain and humidity longer than untreated down.

Manufacturers are clear on one point: while treated down resists water longer, it is not impervious. If hydrophobic down gets wet enough, it will fail. However, in the event of getting waterlogged, another selling point of treated down is that is recovers (i.e., dries) faster than untreated down.

So while this innovative development is good news, you still have to take proper care of your down.

Down Metrics

Down is usually rated by ‘fill power’. This is an arcane industry measurement which has made its way from the engineering lab to our everyday vocabulary. The fill power expresses the area, in cubic inches, that an ounce of feathers will cover. An ounce of 600-fill down covers 600 cubic inches while an ounce of 800-fill will cover 800 cubic inches.

Understanding this odd measuring method will help you pick the right down gear to suit adventures. Higher fill means higher quality, so less feathers are required to achieve a level of warmth. Imagine two 30 degree sleeping bags, one with 600-fill down and the other with 800-fill insulation. They keep you equally warm but the 800-fill bag, due to less material, will be lighter and more compressible. Because of the superior down, the 800-fill bag will be more expensive than the 600-fill bag.

While an ultralight backpacker might choose the highest fill power to get the lightest and most compressible jacket or sleeping bag, a car camper could get the same warmth from lower-fill gear and save a little money.

Duck and goose feathers top out around 900-fill. While this seems to serve birds well enough, science has created higher fills by mixing in synthetic substances or processes to increase the insulating capabilities of natural down. So you may see higher fill numbers on some companies’ products.

A Word About Ethics

There are ethical considerations when considering down.

Luxurious eider down is respectfully gathered by hand from the nests of these wild birds. That intensive labor and limited supply contributes to its cost. Most commercial down, however, is procured from ducks as a by-product of the food industry. Duck down is more common than goose down in the marketplace because, worldwide, duck meat is more popular.

While trade groups report that the majority of down comes from deceased ducks after they are processed as food, the cruel practice of plucking feathers from live birds has been discovered in several manufacturers’ supply chains. In response, companies have developed policies in hopes of preventing this.

Many companies utilize only down that has been RDS (Responsible Down Standard) certified. Down industry groups likewise pledge to trade in only cruelty-free down. Some companies have gone another step and refuse to source even food by-product down.

The Takeaway

Down, for its weight, is one of the best insulating materials known. It has kept birds warm in some of the coldest places on Earth, but recent developments may push the capabilities of down even further.

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