Yellowing

Sometimes white and light-colored garments develop a dingy, yellow appearance. The leading cause of yellowing comes from body oils, especially on polyester. Other culprits are soap residue (particularly on ironed linens), and leaving clothes in dark areas for long periods of time. There are several methods of counteracting this problem. Wash the clothes in the hottest water the fabric can tolerate, and use extra detergent. An old but effective method is to hang yellowed clothing and linens in bright sunlight. Before hanging in the sun, you can apply fresh lemon juice to the garment, and lightly sprinkle with salt.
Caution: Take care to avoid using chlorine bleach on bleach-sensitive fabrics such as spandex, silk and wool, as this can yellow them. If the care label says to dry out of direct sunlight, the garment can be yellowed by exposure to sunlight.