For washing and drying
A mild washing powder: We like Nikwax Down Wash Direct for feathered bags and for synthetic fillings we use Nikwax Tech Wash.
A large enough bathtub or washing machine without a central agitator: The safest way to wash a down bag is by hand in a bathtub. You can, however, use a front loading washer, but don’t use a top loader because its agitator could tear the bag’s seams. If you’re dealing with a two-person sleeping bag that doesn’t open in two pieces, you may have to go to a laundromat to use an extra-large machine.
A large enough dryer: Again, if you have an extra-large bag or extra-small machine, you may need to go to a laundromat to use a dryer there.
A handful of clean tennis balls: Isn’t tennis for you? You can also use balls to dry wool.
To keep your bag clean
A sleeping bag liner: It is a good idea to have a thin bag-shaped lining, often made of silk, for the inside of the bag. We like Sea to Summit’s Silk Stretch Mummy Liner; it is lightweight, absorbs moisture and is easy to carry.
A mattress: It is helpful to have a lightweight foam pad between the bag and the ground (or tent floor). For RVs, we recommend the 3-inch thick Therm-a-Rest LuxuryMap, which is as comfortable as any similar pad and easier to inflate, deflate, roll and store. For backpackers, we recommend the Therm-a-Rest NeoAir XLite – it’s light, warm and comfortable and can hold up to the size of a 1 liter Nalgene bottle. (It is also available in a smaller, slightly warmer women’s version, ideal for smaller sized people who tend to sleep colder.)
A clothesline: If you don’t have a clothesline, a folding drying rack will work too, or even the back of a chair or shower curtain rod.
A damp cloth: It is a good idea to have a cloth that you can dampen to clean the bag if necessary.
Lots of oversized storage: Many sleeping bags come with a small bag (for carrying the bag) and a larger bag; we refer to the latter here.
