How to Clean a Down Sleeping Bag Without Ruining It

The soak takes 15 to 30 minutes. The dry takes two to four hours, checked by hand every 20 to 30 minutes. A down bag is one of the most expensive things most backpackers own, and a top-loading washer with household detergent can leave it clumped and flat in one cycle.

This applies to any down fill, from the 550-fill in a Kelty Cosmic 20 to the 850+ fill in a Western Mountaineering bag.

Wash as rarely as you can. When you do, use a down-specific wash in a front-loader, or any washer with no central agitator, on a gentle cycle with an extra rinse. Then dry on low heat with two or three clean tennis balls or wool dryer balls for two to four hours, breaking up clumps by hand as you go, until no damp clump remains.

Skip it if only the collar and hood are grimy; spot-clean those instead.

Every wash stresses the down and the stitching, so treat a full wash as a once-a-season-or-less job. A liner and airing the bag out after each trip stretch the time between washes.

Spot-clean the usual problems: a grimy collar and hood from skin oils, a muddy footbox, a food stain. Pull the shell away from the down, dab the spot with warm water and a little down wash on a cloth, then rinse the shell without soaking the fill. Save the full wash for when the whole bag smells, feels greasy, or has lost loft.

Down carries natural oils that keep each plume springy. Household detergents are made to strip oils, and they strip these too, leaving the down brittle and prone to clumping. Fragrances and brighteners can leave residue in the fill.

Fabric softener coats the plumes and mats them together. Use a wash made for down, sold at most outdoor shops. The same applies to water-resistant treated down, such as the Nikwax Hydrophobic Down in the Therm-a-Rest Vesper: follow the maker's care label.

Do not use a top-loader with a central agitator; it can tear the baffles, the fabric walls that hold the down in place. If that is all you have, use a laundromat front-loader. In a front-loader: zip the bag closed, loosen the drawcords, use a gentle cycle in cold or warm water, a capful of down wash, and an extra rinse.

Hand washing in a bathtub gives the most control. Run a few inches of lukewarm water, add the down wash, lay the bag flat and press the water through it. Soak 15 to 30 minutes, drain, and press the water out; do not wring or twist. Refill with clean water and repeat until the water runs clear.

Never lift a soaked bag by one end. Wet down is heavy enough to tear the baffles. Gather the bag into a bundle and support it from underneath.

A washed down bag comes out as a flat, clumped mass. A long tumble on low heat restores it. High heat can damage the shell fabric and melt zips and trims, so do not turn it up.

Add two or three clean tennis balls or wool dryer balls. They knock the wet clumps apart as the bag turns. Every 20 to 30 minutes, take the bag out, pull clumps apart by hand, and check nothing is too hot. It is done when it is completely dry with no damp or cold spot anywhere. Moisture left inside can mildew, so if in doubt, run it longer.

Do not store a bag in its stuff sack. Long compression wears down the loft. Keep it loose in a large mesh or cotton storage sack, or hang it in a dry closet out of the sun.

If a bag has lost loft over years of use, a proper wash often brings it back by removing body oils. A low-heat tumble with dryer balls, without washing, can also fluff a tired bag before a trip. A bag that has lost loft has lost warmth, whatever its rating says.

Can I use a regular washing machine? Only a front-loader or another machine with no central agitator, on gentle, with down wash.

Do I need dryer balls? They help a lot. Without them, the down is more likely to dry in dense lumps that do not fully re-loft.