If in doubt, wash it with cold or cold water. For light use and dirt, your standard detergent will work well. If you're dealing with particularly worn white garments, add a clothing enhancer or use a stain removing detergent instead. After the wash cycle is finished, check if the clothes are still stained.
Use hot water or the hottest water recommended for the fabric to help remove body grease and dirt that can dull the material. Wash on a normal or heavy-duty program, depending on the severity of stains or discoloration. White clothes should be washed with a detergent designed to lighten whites. Keep it away from chlorine bleach and fabric softener.
Always check the label and wash the garment at the recommended temperature. For an extra touch of freshness, add distilled white vinegar to the final rinse. Allow white garments to dry in sunlight. Whether it's sweat or deodorant residue, not pretreating these types of stains can create a disaster for your white shirt.
Follow these instructions carefully to keep your white clothes white or eliminate discoloration from white clothing. For bright whites that are soft, clean, and sparkling after washing, use distilled white vinegar in the final rinse. The best way to preserve whiteness is to wash white garments together in the hottest water that the fabric tolerates (water that is at least 120 degrees is most effective in removing dirt). Bleach can and will remove those brighteners from the fabric, leaving the whites dirty and dull, especially if your best white shirt has polyester or some other synthetic content.
Which, in the case of whites that have turned a little yellow, is exactly what you want, because blue and yellow are facing each other on the color perception wheel, so adding a bluish agent to something yellow will make it look bright white to the eye. Of course, it's easier to prevent whites from fading, but it's possible to put yellow and gray clothing back into white. White clothing can be made with many different fibers and is treated with brighteners to ensure that it looks vibrant and white. Washing white clothes separately will prevent color bleeding and transfer of colored clothing, leaving white fabric with a dull appearance.
When making white fabrics, they are often treated with optical brighteners, which are chemicals that increase whiteness. As the owner of two sets of linen, huge fluffy towels and about 12 white t-shirts that have seen better days, I am also interested in any advice that will help me reverse the damage that misuse, the passage of time and my wrong washing habits have caused.