Care

Most cotton-filled duvets can be washed at home. The limits are the size of the drum and the hours it takes to dry the middle.

What size machine does it need?

For a queen or king, a washer above 4.5 cubic feet, ideally a front-loader or an impeller top-loader of 5.0 cubic feet or more.

Washers above 4.5 cubic feet fit a king-size comforter in Consumer Reports testing. If you have to push the comforter in to make it fit, the machine is too small (Wayfair). A central agitator can damage the stitching that keeps fill spread out (Truuce), so a laundromat front-loader is the safer choice if yours has one.

How do you dry it all the way through?

Low heat, dryer balls and several cycles, taking it out every 30 to 40 minutes to shake the fill back into place.

Cotton holds water deep in the batting. By our arithmetic, a 300 GSM full/queen insert at 88 by 92 inches (Delara on Amazon) holds about 3.5 lb of cotton before the shell. Keep going until the middle feels as warm and light as the edges, then let it air on a rack if you are unsure. The washing guide has the full routine.

What water temperature should you use?

Follow the label. Hot water kills dust mites, but a cold wash still removes most of the allergen.

In a 1992 laboratory study, water at 55°C (131°F) or hotter killed all the mites, and a cold wash cut allergen by more than 90% while leaving most mites alive (McDonald and Tovey, 1992). A cover you can wash hot and often does most of that work, and the insert can then go in far less. Our insert guide compares what cotton-fill sellers print about care.