If your new sofa cover doesn't match your home's decor, or if an old one looks worn and stained, consider dyeing it. While dyeing fabric may seem difficult, it's simple to dye fabrics any shade of the rainbow using a washing machine. Most natural fabrics, such as wool blends or cotton, absorb the new colour evenly.
Adjust the settings on your washing machine so that you use warm water, the least amount of water possible and the longest time setting. Remove the cover from the sofa.
Mix your soda ash, non-iodised salt and dye in a container with a plastic spoon, combining them with a little water to make a slurry. Turn the washing machine on so that it fills with water and starts agitating.
Add the dye while the water is agitating and allow the water and dye to mix for a couple minutes. Add the cover to washing machine.
Agitate the washing machine for a couple minutes and then stop it for a few minutes, allowing the cover to soak up all the dye. Set the cycle back to the beginning to prevent the water from draining. Repeat this for 30 minutes to an hour, depending on how dark you want your fabric.
Select a rinse cycle with cool water. Add professional textile detergent and wash the couch cover again in hot water, which will remove the excess dye. Allow it to air dry completely before putting it on your sofa.
Professional detergents are best for freshly dyed fabrics and are available at craft shops or high-end supermarkets.