Keep white cotton shirts white by washing white clothes separately and by refraining from overloading the washer. Separating white clothes and washing them on their own prevents color transfer from other fabrics, and allowing enough space in the washer for detergent to do its work ensures that the soil is washed away from clothing during the rinse cycle. Address any graying or yellowing in cotton shirts promptly to restore whiteness.
Treat stains on white cotton shirts as soon as they are noticed, in order to prevent them from setting. About.com Laundry section advises consumers not to overuse chlorine bleach, because it can cause yellowing in white cottons. Instead, choose an oxygen-based bleach to remove stains and keep white cotton shirts white. Because drying a white shirt with a stain can cause the stain to become permanent, avoid drying white shirts that are stained until the stain is completely removed.
About.com Laundry suggests to dry white fabrics outside on a clothesline in the sun. The ultraviolet rays of the sun are helpful in brightening and whitening cotton clothing. When white clothes become dingy looking or take on a gray, unpleasant tint, use a color remover to brighten them. This drying technique brings back the stark whiteness to the fabric.