To get sweat stains out of a hat, make a paste of baking soda and a little water (or mild detergent), work it into the stained sweatband with a soft toothbrush, let it sit 15 to 30 minutes, then hand wash the hat in cold water and air dry it. Fresh stains usually lift in one round; old yellow lines may take two or three.
Below: what actually causes the stain, which fix to use for which hat, and how to stop it from coming back.
Why hats get sweat stains
The yellow or white line on a sweatband isn't just water. It's sweat salts plus skin oil, sunscreen, and hair product, and it builds up every time you wear the hat. Salt leaves white crust lines on dark hats; oil and protein leave yellow-brown rings on light ones. The longer it sits, the harder it sets, which is why a quick rinse after a sweaty day beats a big scrub a month later.
Which method to use
| Stain | Try first | If it's stubborn |
|---|---|---|
| Fresh, light ring | Mild detergent and a toothbrush, then hand wash | Baking soda paste |
| Yellow sweat line on a light hat | Baking soda paste, 30 min | Repeat; on hats whose label allows it, an oxygen-based stain remover soak |
| White salt crust on a dark hat | Cool water rinse and detergent scrub | A splash of white vinegar in the rinse water |
| Makeup or sunscreen on the band | A drop of dish soap worked in first | Repeat before washing |
Always do a quick color test first: press a damp white cloth against a hidden spot. If color comes off, spot clean only.
Step by step: removing sweat stains from a cap
- Mix a paste of baking soda and just enough water to make it spreadable. A few drops of mild detergent help with oily stains.
- Work it into the sweatband with a soft toothbrush. Short strokes, not hard ones; you're lifting the stain, not sanding the fabric.
- Let it sit 15 to 30 minutes.
- Hand wash the whole hat in cold water with a few drops of mild detergent, about 30 minutes of soaking. Full steps are in how to wash a hat.
- Rinse well, press out the water (don't wring), and air dry crown-up. Don't put it in the dryer.
- Check it dry. Sweat lines often look gone when wet and reappear as the hat dries. Repeat if needed.
How to clean sweat out of a MONGO hat
The method above works for MONGO hats, with the care label as the rule: hand wash cold, mild detergent, no bleach, no washing machine or dryer, air dry crown-up. That means no chlorine bleach and no "bleach" products on the band. A baking soda paste and a toothbrush are fine. If you sweat hard in your hat, the perforated side panels on the XL Performance Snapback help it dry out faster between wears.
How to prevent sweat stains
Getting stains out is work. Not getting them is easier.
- Use a sweatband liner. Disposable or washable adhesive liners stick inside the band and catch sweat and oil before the hat does. Swap them every few wears.
- Rotate your hats. Wearing the same cap every day means it never fully dries. Two or three in rotation each get a day off to air out.
- Air it out after every sweaty wear. Crown-up, not balled up in a gym bag. See how to store hats.
- Rinse the band after a hard sweat. Thirty seconds of cool water and a wipe stops salt from building up.
- Let sunscreen and hair product soak in before you put your hat on.
- Wear a hat that fits. A hat that's too tight presses the band hard into your forehead, so more sweat and oil soak in along one line, and it can give you a headache too (here's why). If you're wearing a snapback on the last notch, measure your head. At 23.6 in (60 cm) or more, MONGO hats in sizes 7½ to 8½ will sit right instead of squeezing.
What not to do
- Don't use chlorine bleach on colored hats, or on any hat whose label says no bleach.
- Don't use hot water. It can set protein stains and shrink some fabrics.
- Don't scrub with a stiff brush. It fuzzes the fabric and makes the stain look worse.
- Don't dry with heat. Read can you put a hat in the dryer before you're tempted.
For white hats specifically, see how to clean a white hat.
FAQ
How do you get sweat stains out of a hat?
Work a paste of baking soda and a little water into the sweatband with a soft toothbrush, let it sit 15 to 30 minutes, then hand wash the hat in cold water with mild detergent and air dry it crown-up. Repeat for old stains.
Can old yellow sweat stains come out of a hat?
Often, but it may take two or three rounds. Old stains have set in, so let the paste sit longer and check the hat after it's fully dry, since stains can look gone while wet.
Does vinegar remove sweat stains from hats?
A splash of white vinegar in the rinse water can help with white salt lines on dark hats. Do a color test on a hidden spot first.
Can I use bleach on a sweaty hat?
Not on colored hats, and not on any hat whose label says no bleach, including MONGO hats. Baking soda and mild detergent are safer.
How do I stop my hat from getting sweat stains?
Use an adhesive sweatband liner, rotate between two or three hats, let your hat air out crown-up after sweaty wears, rinse the band after a hard sweat, and wear a hat that fits rather than one that presses into your forehead.