Pre-treat with a hydrogen peroxide and baking soda paste

Mix equal parts hydrogen peroxide (3%), baking soda, and water into a spreadable paste, apply it to the yellowed areas, and let it sit before washing. This combination lifts most sweat stains in one treatment.

Steps

1. Mix the paste: Combine roughly 1 tbsp each of 3% hydrogen peroxide, baking soda, and water in a small bowl. Adjust to form a thick, spreadable consistency.
2. Apply to stains: Spread the paste generously over the yellowed areas and gently scrub it into the fabric with an old toothbrush.
3. Let it sit: Leave the paste on the stain for 30-60 minutes.
4. Wash normally: Machine wash in warm water (check the care label first).
5. Check before drying: Inspect the stain before putting the shirt in the dryer. Heat sets stains, so repeat the treatment if needed.

Why It Works

Hydrogen peroxide is a mild bleaching agent that breaks down the organic compounds in sweat stains. Baking soda provides gentle abrasion and helps deodorize the fabric.

Tips

• Test first on an inside seam if the shirt is colored, since peroxide can lighten some dyes
• Works best on cotton and cotton-blend fabrics
• Do not use on silk, wool, or delicate fabrics