Feather-filled cushions are ideal for people who prioritize softness in a sofa. Feathers are the cheaper option; companies usually use duck or chicken feathers as filling. Down comes from the plush underbellies of geese. Expect to pay more for a sofa with down-filled cushions. Feathers won't dry properly if they get wet, but waterproof covers add some protection from spills. Cushions are wrapped in feather-proof casings to prevent feathers from slipping out. One-hundred-percent down can get lumpy over time unless the down is sewn into individual pockets or baffles. For something firmer, opt for cushions with a foam core and an outer layer of feathers or down.