Greying and yellowing are two problems affecting fabric and upholstery. Usually, a build-up of dust and other debris around the area causes the discolouration. Dyes from the clothing of people sitting on the furniture, as well as residue from cleaning products such as soap or bleach, may also cause the fabric to appear yellow. Cleaning the yellow upholstery may help bring back the original colour of the piece for a brighter and newer appearance.
One of the most common ways to clean yellowed fabric is with a colour whitener or a colour brightener. Use a colour whitener only on upholstery that's white, as it will whiten any spot it touches. If you use the product on a dark piece of furniture, it may severely lighten any area you place the whitener. Colour brighteners are more effective on white fabrics. If your upholstery is a different colour, try using a colour wash or white wash product. This removes the yellowing on the fabric, without damaging the colours of the piece. Always test the product on a small section before using it. Place a small amount on the back or bottom of the upholstery that is out of view.
One possible cause of yellowing is a build-up of soap or bleach. If bleach was ever used to clean the upholstery before, then a colour remover is the most effective. This product removes any leftover traces of the bleach, by breaking down the components of the bleach and won't damage the original colour or pattern of the upholstery. It works on both coloured and white fabrics. Once you apply the product, you need to rinse it off with fresh water and let dry. You may need to repeat the process to remove all traces of the yellowing.
Soaking the yellowed material in a vinegar solution may help clean it. Combine one gallon of hot water, with one teaspoon of white vinegar and 1/8 cup of bleach. Wear rubber gloves when cleaning the fabric to protect your skin and only use it in an area with adequate ventilation. Use a scrub brush to apply the solution to the fabric and rub it deep into the fabric. Let the mixture sit for 30 minutes and then use cool water, to remove the solution. This should take away any traces of the yellowing in the upholstery.