How to Wash an Underquilt

By topquilt.com · Updated Oct 21, 2026 · 7 min read

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Underquilts get dirtier than you'd think. They don't touch your skin, but they hang in dust, pollen, campfire smoke and sap, and they get packed alongside muddy gear. Over time that grime and body oil working through the hammock fabric can reduce loft. The good news: knowing how to wash an underquilt is mostly the same as washing any quilt, with a few underquilt-specific steps around the suspension and the extra length.

This guide focuses on those underquilt differences. For the full background on down care, read how to wash a down quilt and how to dry a down quilt; for synthetic insulation, see washing synthetic quilts.

When to wash an underquilt

Underquilts need washing less often than top quilts. Wash yours when:

• Loft has dropped and shaking or a short low-heat tumble doesn't bring it back.
• It smells, from smoke, mildew or general use.
• It's visibly dirty, stained with sap or mud.
• You're putting it into long-term storage after a heavy season.

Every wash causes a little wear, so don't wash on a schedule. Spot-clean small stains with a damp cloth and a bit of tech wash instead. Using an underquilt protector helps keep the shell clean between washes.

What you need

• Down cleaner for down quilts: Nikwax Down Wash Direct or Granger's Down Wash.
• Technical wash for synthetic quilts: a gentle tech wash such as Nikwax Tech Wash.
• Dryer balls or clean tennis balls: wool dryer balls help break up clumps.
• A large front-loading washer and dryer, at home or at a laundromat.
• A mesh laundry bag or zip bag for removed cords and hardware.
• Optional: a large basket for carrying the wet quilt, which is heavy and fragile.

Step 1: Prep the underquilt and suspension

This is the step that sets washing an underquilt apart from other quilts. Underquilts have shock cord, cord locks, static lines and sometimes small carabiners. In a washer, these can wrap around the quilt, knot themselves, scratch the drum or snag the delicate shell.

1. Remove detachable suspension. If the main suspension lines unclip or untie, take them off. Note or photograph how they were rigged so you can restore your setup. Put the hardware in a mesh bag.
2. Handle the end-channel shock cord. If the cord in the end channels can be pulled out easily, many owners remove it to wash and rethread it afterward. If it's sewn in or fiddly, cinch the ends loosely and tie the cord tails together so nothing dangles.
3. Secure side pull-outs. Tuck or tie any side cords so they can't wrap around the quilt.
4. Empty and inspect. Shake out debris, check for holes and patch them first with a gear repair patch so down can't escape. See how to repair a quilt.

Step 2: Wash the underquilt

Machine washing (front-loader only)

1. Clean the detergent drawer and run a quick rinse cycle if the machine has had regular detergent in it.
2. Place the underquilt in the drum by itself.
3. Add the recommended amount of down wash (or tech wash for synthetic).
4. Choose a gentle or delicate cycle with warm or cool water per the quilt maker's care label.
5. Run an extra rinse cycle to remove all soap. Leftover cleaner can reduce loft.
6. Spin on a low-to-medium setting to remove water without stressing baffles.

Avoid top-loaders with a central agitator. The agitator can twist the quilt hard enough to tear baffles. If your home machine is small, a laundromat's large front-loader is the better choice.

Hand washing in a bathtub

1. Fill a tub with lukewarm water and mix in the cleaner.
2. Submerge the quilt and press out the air.
3. Gently knead and press for a few minutes, then let it soak according to the cleaner's directions.
4. Drain, then press water out with your hands. Refill with clean water and rinse, repeating until no suds appear.
5. Press out as much water as possible. Don't wring or twist.
6. Lift the whole quilt with support from underneath; a waterlogged down quilt is heavy, and lifting by one end can tear baffles.

Step 3: Dry a long underquilt fully

Drying takes the most time and causes the most problems. Full-length underquilts are long and, for winter models, very lofty, so they need a big drum to tumble freely.

1. Use a large dryer. A commercial front-load dryer at a laundromat is ideal. If the quilt is packed tightly into a small drum, it won't dry evenly.
2. Set low heat. High heat can melt thin nylon shells and damage synthetic insulation.
3. Add dryer balls. Two or three wool dryer balls or clean tennis balls help break up down clumps.
4. Check every 20-30 minutes. Pull the quilt out, break up clumps by hand and turn it end-to-end so the ends dry too. Underquilt ends can stay damp, as the cinched channels hold water.
5. Keep going. Down underquilts often need several hours. It's only done when there are no clumps anywhere and the quilt feels evenly lofty.

Synthetic underquilts dry faster but still need low heat. For the full process, see how to dry a down quilt.

Step 4: Restore loft and reassemble

After drying, give the quilt a good shake and let it loft for a few hours. If it still looks thin in places, a few more minutes in the dryer with dryer balls usually helps; see restore quilt loft if problems persist.

Then rethread the end-channel shock cord, reattach the suspension lines and hardware in your original setup, and check fit on your hammock. Use how to hang an underquilt to dial everything back in.

Down vs synthetic underquilts: what changes

The washing process is broadly the same for both insulation types, but a few details differ:

Synthetic underquilts like APEX-filled models tolerate damp better, but they're more vulnerable to heat. Don't be tempted to speed drying with a hotter setting. If you're unsure what your quilt is filled with, check the care label or the maker's site; our down vs synthetic underquilts guide explains how the two compare in use.

Restoring water resistance

Many underquilt shells have a DWR (durable water repellent) finish that helps shed light moisture. Repeated washing can reduce it. If water no longer beads on the outer shell, you can refresh it with a spray-on DWR treatment applied to the outer shell only, following the product's instructions. Some down washes are designed to be gentle on DWR; check the label.

Avoid treating the inner shell, which faces the hammock; the goal is breathability on the inside and light water resistance on the outside. If you hang in wet, windy places often, an underquilt protector does more to keep the quilt dry than any DWR treatment.

Underquilt washing mistakes to avoid

Storing your underquilt after washing

Never store an underquilt compressed in its stuff sack. Keep it loose in a large cotton or mesh storage sack, or hang it in a closet. Make sure it's completely dry first. Our how to store a quilt guide covers the details, and a well-stored underquilt keeps its loft for many seasons.

If you're considering replacing an older underquilt rather than reviving it, see our picks for the best underquilts.