Slipcover
Every year at Mount Vernon in late spring, slaves and servants aired the house, washed bedsteads, and put covers - or cases, as they were known - on the upholstered furniture. Such cases would have protected the expensive upholstery from increased dust and exposure to sunlight in the summer months. This dimity chair cover entered Mount Vernon's collection with one of the scallop-shell chair cushions worked by Martha Washington. Whether the cushion and cover would have been used together, and where in the house they would have been placed, is the subject of ongoing research.
See also W-1533/A.