To get clothes really white, use hot water and detergent for whitening, bleach or natural home remedies. White clothes should only be washed with other whites to prevent color transfer. Treat stains ahead of time. Bluing agents and Borax also brighten whites.
The old fashioned method of washing white clothes still works for cottons and linen. Add equal amounts of laundry soap and baking soda to a big enamel or stainless steel pot then fill with cold water. Put clothes in the water, heat to boiling and let boil for thirty minutes. Drying in the sun also works to bleach out white clothing. Bleach whitens clothes, though over-use can yellow fabrics over time. Oxygen based bleaches such as OxiClean are less likely to yellow fabrics.
Natural home treatments for whitening clothes include baking soda, aspirin, vinegar and lemons. Clothes can be soaked in a solution of 1 cup of baking soda dissolved in a gallon of fresh water. Alternatively, clothes can soak in a hot water bath with five aspirin tablets dissolved inside. A paste of aspirin and water also works to lighten yellow stains, such as sweat or old food stains. Alternatively, add 1 cup of vinegar during the rinse cycle. For dingy clothes, boil lemon slices in a pot of water and soak cottons or linens until the water cools.