If you are referring to the entire cushion, you would not want to wash them because the foam would absorb water and become mildewed or moldy.
If you are referring to the cushion cover only, the reason is probably because the covers were not made to be removable.
- Furniture cushions can be either removable (you can pick them up) or non-removable (permanently attached to the furniture.)
- Back cushions may or may not have zippers, depending on style and price.
- Removable seat cushions typically do have zippers. Non-professionals assume that the purpose of those zippers is to allow the covers to be replaced.
Actually, the zippers used in a large percentage of mass produced seating are not large enough to make cover removal easy or practical for non-professionals.
In low and mid-priced seating, the primary purpose of the zipper is to make the cushions easy to “stuff” in the factory (insert the cushion core into the cover.)
- This stuffing is done using huge hydraulic machinery with mechanical fingers that can expertly stuff a cushion in just a few seconds.
- Smaller companies that stuff cushions by hand use larger zippers. The hand stuffing process takes several minutes, even for a trained professional. Amateurs can spend an hour trying to stuff a cushion and still not get it looking just right.
- In order to make a cushion cover that can be easily removed and replaced by an unskilled consumer, the zippers have to extend all the way across the back and part way up the sides. Few companies spend the extra money to do this.
Extended zippers are only one requirement for a cushion that has easily removable (and replaceable) covers.
- Mass produced cushions usually consist of a foam (or spring) core with a polyester wrap glued to outer surface.
- This polyester wrap (and the foam) tend to stick to the covers, making removal and replacement difficult, even with extended zippers.
- Cushions that are designed to be easily removable and replaceable by consumers also need a woven fabric covering around the cushion core and polyester fiber wrap.
- This fabric jacket is smoother than the foam and fiber. It allows the cover to slide off and on without sticking.
- The fabric jacket adds cost to a part of the furniture that cannot be seen, has only a minimal effect on comfort and that most customers will never even think about.
- As a result, furniture manufacturers selling in a competitive price environment do not spend money to ensure easy removal of cushion covers.
Cushions made with covers that are easily removable and replaceable can be found on better quality furniture — but not always.
Ease of cleaning, repair or replacement is rarely a primary consideration for furniture designers at any price level.
