Plumping Up.
Is an essential part of feather cushions to keep your furniture looking good, in most cases this has to be done daily or the cushions will look flat and limp.

A good plump up in the covering fabric will revive the cushions back to their original look and feel.

Cleaning.
Sofa cushions may need to be cleaned but, this may not be possible as they could be too large and dense for home washers. Professional dry cleaning is recommended or light dabbing with a sponge.

Pillows and scatters are small enough for home washers. Wash on a gentle cycle with a minimum amount of detergent. During the dry cycle periodically fluff them up to loosen the feathers.
Several cycles may be required to thoroughly dry them, if they are not dried properly the feather will remain damp. Within days they will begin to rot and smell, then their will be no alternative but to destroy the cushion.

Important Note :
Do not let the new cushion stretch the fabric at the ends of the zip runner (fig 2).
The sewing to stop the zip running off the slider can easily break and the zip will run off, or even break the zip slider, in most cases they are only plastic.