Quick answers:
Yellow sweat stains can be challenging to remove, but it is possible with the right techniques and products. Some quick tips:
- Treat the stains as soon as possible – the longer they set, the harder they’ll be to remove
- Pre-treat with an enzymatic cleaner or diluted hydrogen peroxide before washing
- Wash in hot water using an oxygen-based bleach or detergent with enzymes
- For really stubborn stains, try soaking in an oxyclean solution before washing
- Increase washing machine agitation by using extra rinse cycles or washing fewer items at once
- Air dry in direct sunlight, as the UV rays help to further break down the stain compounds
- Repeat treatments as needed for particularly difficult stains
With some determination, it is possible to get those unsightly yellow pit stains out of your clothes and linens. The key is using the right products and techniques consistently over time.
What causes yellow sweat stains?
Yellow sweat stains are the result of a chemical reaction between sweat, body oils, and dead skin cells. Here’s a closer look at the key culprits:
Sweat
Sweat itself is initially odorless and colorless. But as it mixes with bacteria on your skin, it can take on an unpleasant smell and yellowish tinge. The primary ingredient in sweat is water, but it also contains:
- Salt – comprised of sodium, potassium, and chloride
- Urea – a compound found in urine
- Amino acids
- Sugars and carbohydrates
- Ammonia
When this sweat soaks into clothing and dries, the salt, urea, and acids can remain behind, leaving a yellowish residue.
Body oils
Apocrine glands in the armpits and groin secrete oily substances along with sweat. These oils contain certain pheromones and proteins. When this oily sweat accumulates on clothing and mixes with dirt and dead skin cells, yellow staining develops.
Dead skin cells
Your skin is constantly shedding dead skin cells. These cells contain keratin, a tough, insoluble protein. When keratin is mixed with sweat and body oils, it bonds strongly to fabric fibers and causes yellowing.
Deodorant ingredients
The aluminum and zirconium compounds found in many deodorants and antiperspirants can react with sweat and oils. This creates a waxy, stubborn substance that leads to yellow discoloration.
How Do Sweat Stains Turn Yellow?
Now that we know what’s in sweat, let’s look at the chemical reactions that cause this unsightly yellowing effect:
Oxidation
When sweat-soaked clothing is exposed to air, the amino acids, proteins, lipids, and urea undergo an oxidation reaction. This is the same process that causes iron to rust. Oxidation turns these compounds yellowish or orangey-brown.
Alkalinity
Fresh sweat is slightly acidic with a pH between 4-6.5. But as it evaporates and reacts with the alkaline components in body oils and dead skin cells, the pH rises. This more alkaline environment speeds up oxidation and causes browning.
Polymerization
Some of the organic compounds in sweat undergo a chemical reaction called polymerization when exposed to air. They bind together into longer, more complex and colorful molecules. This polymerization contributes to more stubborn staining over time.
Dye transfer
The aluminum salts in deodorant can react with pigments found in colored clothing. This transfers some of the dye molecules onto the armpit areas of shirts and blouses, adding to the yellow discoloration.
Heat
Warm temperatures accelerate chemical reactions. So leaving sweat-stained items balled up in a hot hamper or drying them using heat speeds up oxidation, polymerization, and dye transfer – resulting in more set-in yellow pit stains.
Home Remedies for Yellow Sweat Stains
Now that you know how those stains develop, let’s look at some homemade solutions for tackling them:
Lemon juice
The natural acidity in lemon juice helps to break down the bonds of stubborn sweat stains. Try soaking the fabric in a mixture of lemon juice and water before washing. For extra stain-fighting power, sit the garment in direct sunlight after soaking.
White vinegar
Like lemon juice, white vinegar contains acetic acid that works to dissolve sweat residue. Fill a spray bottle with equal parts vinegar and water and spritz it directly on old stains. Let it soak in for an hour before washing.
Hydrogen peroxide
Hydrogen peroxide is an effective bleaching agent that can help restore discolored areas and boost your detergent’s cleaning power. Pretreat stains by dabbing on diluted 3% hydrogen peroxide before washing. Check labels first, as hydrogen peroxide may discolor some fabrics.
Baking soda
Baking soda is mildly alkaline, which helps it neutralize acidic sweat stains. Make a paste by mixing baking soda with just enough water to form a spreadable consistency. Rub this paste thoroughly into stains and let sit before washing.
Borax
Like baking soda, borax raises the pH of laundry water to help remove acidic grime. For a one-two punch, make a paste with equal parts borax and lemon juice. Apply to sweat stains and let it work for 30-60 minutes before washing.
Meat tenderizer
The enzymes found in unseasoned meat tenderizer help break down the proteins in sweat stains. Make a solution by dissolving 1 tablespoon of meat tenderizer in 2 cups of warm water. Soak white clothes in this solution before washing.
Aspirin paste
Crush up 5-6 uncoated aspirin tablets and mix with just enough hot water to form a paste. Spread this mix on sweat stains and allow it to dry completely before washing. The aspirin’s salicylic acid tackles discoloration.
Salt
For a more abrasive scrub, dampen sweat stains and cover generously with table salt. Use your fingers to rub the salt firmly into the fabric, then rinse and launder as usual. The salt works as a mild bleach and stain remover.
Cleaning Products for Sweat Stains
In addition to home remedies, there are some commercial cleaning products that work wonders on yellowed sweat stains:
Oxygen bleach
An oxygen bleach powder, like OxiClean, uses the stain-fighting power of hydrogen peroxide without the risks of chlorine bleach. Make a concentrated paste and apply it directly on set-in stains before washing.
Enzymatic cleaners
Enzyme-based pre-treatments break down organic matter using compounds like protease and amylase. Spray or rub an enzymatic cleaner like Biz, Persil ProClean or Shout Advanced directly on old sweat stains.
Antiperspirant deodorants
Rubbing an old-school antiperspirant containing aluminum chloride, like Certain Dri, into stains helps block sweat and prevent further yellow discoloration. Rinse thoroughly after 10 minutes.
Color-safe bleach
An oxygen-based, chlorine-free bleach like Clorox 2 or OxiClean Versatile Stain Remover can penetrate stubborn sweat stains on white and colorfast laundry. Use separately before washing.
Laundry detergent booster
Detergent boosters and stain remover sticks contain active enzymes and oxifiers to get out grime. Add a booster like Tide Kick or Shout Color Catcher with your regular detergent cycle.
Bar soap
For quick pre-treatment, simply rub a bar of soap like Zote, Fels-Naptha or Grandma’s Lye Soap directly on stains. The soap helps lift discoloration so detergent can remove it more effectively.
Tips for Washing Away Sweat Stains
Proper laundry techniques are key to actually washing away yellowed sweat stains after pre-treating. Here are some top tips:
- Wash stains ASAP – the longer they sit, the harder they’ll be to remove
- Wash in the hottest water safe for the fabric
- Use heavy-duty detergent with stain-fighting enzymes and bleaches
- Pretreat stains with a laundry booster or paste mixture
- Soak clothes in an enzymatic cleaner or oxygen bleach solution if stains are heavy
- Add white vinegar to the wash cycle – the acid helps dissolve residue
- Use extra rinse cycles to remove all traces of detergent and pre-treatment
- Air dry in direct sunlight rather than the dryer – the UV rays further disinfect and deodorize
- Wash whites separately from colors to avoid dye transfer
- Was just a few items at once for better agitation
With repeated washing using these tips, even the most stubborn yellow sweat stains can eventually be removed.
Preventing Future Sweat Stains
Prevention is the best medicine when it comes to sweat stains. Here are some proactive steps you can take:
- Wear undershirts to absorb sweat rather than your outer layers
- Change out of sweaty clothes soon after exercising
- Use an clinical-strength antiperspirant/deodorant
- Wash clothes after just 1 or 2 wears if you sweat heavily
- Turn garments inside out when washing to maximize cleaning
- Avoid leaving sweaty clothes balled up in the hamper
- Change and wash dirty sheets at least once a week
- Limit use of lotions and oils on areas that contact clothing
- Wear breathable, natural fabrics when possible
Making these habits part of your routine can go a long way towards keeping fresh and stain-free.
When to Call in a Professional
For badly stained and discolored clothing or linens, a professional cleaner may be your best bet. They have access to powerful chemical solvents and tools like steamers and ultrasonic cleaners.
Here are some signs it’s time to seek professional laundry services:
- Stains have turned a dingy brown/orange shade and won’t lift with home treatments
- Odor remains even after thorough washing
- Specialty care items like silk, linen or wool
- Heavily soiled upholstery or furniture
- Bleaching has damaged the fabric or made holes
Reputable professional cleaners have experience lifting challenging stains without harming fabrics. For heavily soiled and discolored items, the steep cost of pro services can be worth it.
The Bottom Line
While yellowed sweat stains can be vexing, don’t give up hope. With consistent effort using the right combination of commercial cleaners, home remedies, proper laundry techniques and preventive habits, you can keep your clothing and linens fresh. Stick with it and those unsightly pits stains will eventually meet their match.
