Sweat stain gets harder to shift the longer it sits. For yellowing, oxygen bleach and vinegar beat chlorine bleach.
That yellow underarm mark is not sweat alone: it is the aluminium in antiperspirant reacting with proteins in sweat, which is why an ordinary wash does nothing. Chlorine bleach can actually darken it. Oxygen bleach plus vinegar is the standard approach, and set-in marks need several rounds.
Method by fabric
White cotton
What you need
- Oxygen bleach
- Vinegar
- Baking soda
- Soft toothbrush
Steps
- 1Pour a 1:1 vinegar and water mix on the stain and leave thirty minutes.
- 2Sprinkle baking soda to form a paste and work it in with a soft toothbrush.
- 3Soak two hours in lukewarm water with oxygen bleach.
- 4Wash below 40ยฐC.
- 5Repeat the whole process before drying if it is lighter but still there.
Cotton and blends
What you need
- Vinegar
- Mild detergent
- Lukewarm water
Steps
- 1Soak thirty minutes in one part vinegar to two parts water.
- 2Apply mild detergent and knead it gently.
- 3Rinse lukewarm and wash.
- 4Dry in the shade.
Caution
Test first โ vinegar can lift colour from dark fabrics.
Synthetics
What you need
- Oxygen bleach
- Lukewarm water
Steps
- 1Soak an hour in water below 40ยฐC with oxygen bleach.
- 2Knead gently and rinse.
- 3Wash cool and dry in the shade.
Caution
Technical sportswear coatings are damaged by heat and strong detergents.
Never do this
- Chlorine bleach โ it can deepen the yellow
- Hot washes โ they set the mark
- Dressing immediately after applying antiperspirant โ let it dry first