Quick answer: To whiten clothes, soak washable whites in hot water with powdered oxygen bleach overnight, then rewash. For yellow sweat stains, pretreat first and use 3% hydrogen peroxide or an oxygen bleach soak, but never dry peroxide-treated items in direct sun.
If you want to know how to whiten clothes, the best approach is usually not chlorine bleach. For most washable whites, we use hot water, powdered oxygen bleach, and time. For yellow underarm stains, hydrogen peroxide can help restore brightness, but it should be air-dried in the shade or indoors, never in direct sun.
For cotton tees, sheets, pillowcases, and many other washable whites, the most effective method is an overnight soak.
Oxygen bleach works slowly, so patience matters. Heat helps it work better, which is why warm or hot water is important when the fabric allows it.
Yellowing at the underarms and collar usually needs a little extra help before the soak.
Important: Do not dry hydrogen peroxide-treated garments in direct sunlight. UV light can react badly with peroxide and work against your results.
This approach is ideal for white cotton clothing, sheets, pillowcases, and other washable items with dullness or yellowing. For silk, wool, embellished pieces, or garments labeled dry clean only, professional cleaning is the safer choice.
If the item is washable, start with an oxygen bleach soak. If the yellowing is from sweat, pretreat first and use hydrogen peroxide or an overnight soak for the best chance of restoring brightness.
Or ask about any laundry or garment care question