How to Whiten Yellowed White Clothes

Even if you follow all the rules on keeping white clothes white, they can still become yellowed over time. Yellowing quite often occurs on clothes that are stored improperly and react with the cardboard box or wooden shelves. So what to do?
The first step for washable clothes is to mix a solution of warm water and oxygen-based bleach (Oxibleach, Zonrox Color Safe Bleach). Submerge your white garments and allow them to soak for a day. Cover it with plastic and sealed. It is much effective if you will let it sit under the sun.
Then wash as usual, adding 1/2 cup distilled white vinegar to the rinse water.
If possible, dry the clothing outside in the sun. The ultraviolet rays of sunlight will help to whiten the clothes.
Chlorine bleach can be used on cotton fabrics. However, the overuse of chlorine bleach can actually cause clothes to yellow. Only use chlorine bleach if you are familiar with how to use it properly.