Scientists May Have Found a Gentle, Chemical-Free Way to Remove Sweat Stains

Nasty pit stains on white shirts are unsightly, and bleach has long been the go-to way to remove them. Now, a study published in the journal ACS Sustainable Chemistry & Engineering reveals a new contender: blue light.

1. Blue Light Is a Powerful Stain Remover

Blue Light Is a Powerful Stain Remover

To understand the stain-fighting effects of blue light, it helps to know how fabric stain removers work in general. According to Popular Science, these solutions perform their magic through oxidation. A stain gives off a specific color because of how the substance’s molecules reflect light. When you add an oxidizer—such as bleach or hydrogen peroxide—into the equation, the substance’s molecules get broken down so much that they can no longer reflect or absorb light. As a result, the stain seems to disappear. The downside is that these bleaching materials often require other chemicals, solvents, and heat to remove clothing stains, which can harm delicate fabrics. Additionally, these agents aren’t environmentally friendly.

Chemists in Japan found a possible alternative to chemical stain removers in blue light. For their study, the researchers shined high-intensity blue light on three common stain culprits: squalene, an organic compound found in skin and sweat; and beta-carotene and lycopene, which are natural pigments found in certain plants. These substances were placed in vials and exposed to the blue light for three hours. With the help of the surrounding oxygen to broke down chemical bonds, every sample lost its color.

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Next the researchers applied the squalene to pieces of cotton fabric and heated them to simulate aged stains. They then treated the sample with a hydrogen peroxide solution, blue LED light, or UV light for 10 minutes at a time. The blue light turned out to be the most effective at removing the stain. The method even lightened squalene stains on silk and polyester without damaging the materials, and effectively lightened other stains, including orange juice and tomato juice. The chemists still want to do additional testing on blue light stain removal before further developing the method for the public.

Until then, there are a few steps you can take to prevent yellow pit stains. They are caused by aluminum chloride, a common ingredient in deodorant, interacting with your sweat. If you’re looking to avoid pit stains on your beloved white shirts, you can opt for an aluminum-free deodorant instead. Another option is to use an enzyme-boosted laundry detergent after the fact—the cleaner may break down the stain’s proteins and save your shirts.