To remove particularly tough sweat stains, like those that plague the underarms of shirts and dresses, you'll use some of the same active ingredients as mentioned previously, but you'll increase their strength. This can make the treatments more harsh, but also more effective.
Before you start pouring on the product, though, you need to figure out whether the stain is in fact a sweaty one. In the underarm area, you could be looking instead at an antiperspirant stain, which requires a different treatment (see How to Remove Grease Stains and Save Your Clothing). Basically, if it's yellowish and stiff, it's probably sweat; if it's white or clear and greasy, it's probably antiperspirant.
If you determine the underarm stain is sweat, give one of these pre-wash, extra-strength remedies a shot:
- Vinegar -- Just pour it, full-strength, right on the stain and let sit for about 30 minutes.
- Hydrogen peroxide -- Same instructions as vinegar. And remember, do not use hydrogen peroxide on a colored item.
- Ammonia -- Apply it, full-strength, directly on the stain and gently rub it in. You don't need to let it sit before washing.
- Baking soda paste -- Start with full-strength baking soda, and apply just enough water to create a paste. Work it into the stain using a toothbrush, and then let it dry for a couple of hours before washing.
- Aspirin -- Dissolve two to three tablets in a half cup of water, apply it to the stain, and let it sit for several hours before washing.
Since you can throw some fairly heavy-duty cleaners at a sturdy fabric, you've got a good chance of getting the sweat stain out of a basic cotton shirt or dress. But what about when the stain is on something more delicate? This takes a considerably gentler approach.