Couch cushion covers that have shrunk dramatically are not going to return to their original size. However, fabrics that have shrunk slightly or lost their original shape stand a chance of being prodded back into a usable size. To prevent shrinking in the first place, it is important to follow fabric care directions. Knowing the fabric content and how fabrics should be washed can help when trying to second guess possible cleaning solutions.
Identify Fabric Content
Before attempting a cushion cover unshrink process, know what the fabric content is. Contact the manufacturer to identify the content if the fabric treatment label is missing. Synthetics, like polyester, nylon and acrylic, are designed for easy care and generally do not shrink. Cotton and wool, unless treated, will shrink and may continue to shrink even if re-stretched. Blends that include cotton and wool can also shrink, but are generally easier to pull back into shape when placing them on the cushion. Items marked for dry cleaning may have several reasons for this label. They may shrink if soaked in water; they may have a finish or treatment that is damaged by water; or the dye may not be colorfast. Older fabrics may have completely lost their finishes, or may be untreated and may shrink unexpectedly.
Stretching the Fabric
A shrunk wool (or wool blend) cushion cover can be re-stretched when still wet. Soak the couch cushion cover in a mixture of cold water and fabric softener for several hours. Remove and lay flat to dry. Obtaining the exact original shape is always difficult, but a light hand stretching may help. Gently pull opposite corners and edges at the same time and work all the way around the cushion cover. Do this periodically while the cover is drying. Do not rub or agitate the wool (while soaking or while drying) because this causes the shrinking effect to begin all over again. Extreme temperature changes can also cause wool to shrink—putting the cold washed wool into a hot dryer, for example—so do not attempt to dry with a heat source.
Relaxing the Fabric
There are several ways to relax the fabric allowing the fibers to loosen and be stretched. Using a wrinkle releaser on a damp couch cover will relax the fabric giving it a little more length. There are a number of these products being sold—the makers of Downy and Febreeze each have one. A homemade wrinkle releaser can also work. Use a ¼ cup of fabric softener in a spray bottle and fill the bottle with water. Lay the cover flat and spray, tugging the opposite corners and edges simultaneously while it is damp. An eco-friendly alternative uses one part vinegar to three parts water, spray across the fabric and stretch.
An Old Solution
Revisit an old idea for items that are shrunk by several inches or less. Pants stretchers are used to obtain a wrinkle free pant with a uniform crease. They also work to reduce shrinkage in the pant fabric and have been popular at various points in time to stretch jeans. They are made with steel tubing that is formed into the shape of the pant. The device is slipped into the pant legs. The fabric is then stretched by attaching the waist band and the bottom hem to the stretcher. Create a similar device using metal or wood in the final shape needed for the cushion. When the fabric is damp, pull it on to the device to stretch the fabric. Warning: this process may tear more delicate fabrics or distort the couch cover fabrics further and should be used as a last ditch effort.