Why do my white t shirts turn yellow under the arms?

Quick Answers

There are a few common reasons why white t-shirts can turn yellow under the arms:

  • Sweat – The acids and salts in sweat can cause yellowing.
  • Deodorant or antiperspirant – Aluminum and other ingredients can react with sweat and fabrics.
  • Improper laundry – Not enough detergent, insufficient rinsing, or drying at high heat can set stains.
  • Old age – Over time, the fibers in white fabrics break down and become yellowed.

The yellowing is often most pronounced in the underarm area because of the concentration of sweat glands releasing perspiration containing discoloring compounds. Proper laundering and underarm care can help prevent or remove the yellow stains.

What causes yellow stains on white t-shirts under the arms?

There are a few key culprits that can cause white t-shirt armpits to turn yellow:

Sweat

Sweat contains salts, amino acids, proteins, and lactic acid that can react with the fibers in white fabric, leading to yellowing over time. The underarm area has a high concentration of sweat glands, releasing more of these discoloring compounds compared to other parts of the shirt.

The apocrine glands under the arms produce a thicker, milkier sweat that contains higher levels of proteins and acids. These are more likely to leave stains compared to the sweat from eccrine glands found over most of the body. The acidic pH of sweat also promotes yellowing.

Deodorants and Antiperspirants

The aluminum and other active ingredients in many underarm hygiene products can react with sweat and fabrics. This causes yellow pit stains on white shirts.

Aluminum salts cause yellow discoloration by reacting with sweat to form aluminum hydroxide. This builds up on fabric fibers under the arms.

Deodorant staining is made worse if too much product is applied. The sticky solid particles cling to fabric and excess amounts allow more chemical reactions. Spray, gel, and wipe-on deodorants minimize staining compared to dense solid stick versions.

Laundry Detergents

If white t-shirts are not properly pre-treated and laundered, existing sweat and deodorant stains can set and become permanent yellow pit stains.

Using too little laundry detergent can mean soil, body oils, and discoloring compounds are not fully removed. A sufficient amount of an effective detergent helps lift stains and prevent yellowing.

Insufficient rinsing can also leave behind residual soapy detergent or soils that oxidize into yellow stains. Whiter whites are achieved by rinsing thoroughly after washing.

Heat Drying

The high heat of automatic and tumble clothes drying can set and intensify yellow underarm stains. The heat causes sweat residues and deodorant ingredients to further react with fabric. Air drying outside in the sun can also worsen yellowing.

Lower temperature machine drying or hang drying inside avoids this intensifying effect on white shirt yellowing. However, heat can also help remove some staining during the washing stage, so moderate heat is optimal for laundering.

Aging and Wear

Over time, the cumulative build-up of sweat, body oil, and deodorant ingredients will cause permanent discoloration on white fabric. The fibers actually degrade and yellow with regular use and as t-shirts age.

No matter how thoroughly you pre-treat or launder the garment, the yellowing will continue to increase due to this aging effect. The more times the t-shirt is worn and washed, the more pronounced this natural yellowing will become.

How to Prevent and Remove Yellow Stains on White Shirts

Here are some tips to help prevent and remove yellow discoloration and stains on white t-shirt armpits:

Wash Regularly

Launder white shirts after every 1 to 2 wears to prevent sweat and deodorant residue from setting into stubborn stains. Wash heavily worn white tees after just a single wearing. Use a laundry pre-treatment spray or gel on any visible stains before washing.

Use a Laundry Booster or Bleach Alternative

An oxygenated bleach alternative or laundry booster can help whiten clothing and remove set-in stains without the harshness of chlorine bleach. Look for options containing sodium percarbonate or sodium perborate. Add to the wash cycle according to package directions. These help lift discoloration on white fabric.

Check Deodorant Ingredients

Choose an underarm deodorant without hydrogen peroxide, which can cause yellowing. Also avoid aluminum-based antiperspirants. Opt for titanium dioxide, potassium alum, or aluminum-free mineral salt deodorants that are less likely to stain. Apply sparingly to further reduce any fabric reaction.

Turn Garment Inside Out

Turn white tees inside out before washing to place the stained underarm area in full contact with the detergent. This allows for better cleaning action on the affected area during the wash cycle.

Air Dry

Always air dry white t-shirts instead of machine drying to avoid heat setting any stains. Hang dry fully or lay flat to dry. Avoid direct sun exposure which could also intensify yellowing.

Use a Stain Remover Gel

Gently rub a laundry stain remover gel stick into yellow pit stains before washing. Look for ones with enzymes or hydrogen peroxide to break down stubborn discoloration on white fabric. Check the care label and test first on an inconspicuous area.

Method Details
Wash regularly Launder after every 1-2 wears to prevent set-in stains
Use laundry booster Oxygen bleaches help whiten and remove discoloration
Check deodorant ingredients Avoid aluminum and hydrogen peroxide formulas
Turn garment inside out Places stained underarms in full contact with detergent
Air dry Avoid heat setting stains by line or flat drying
Use stain remover gel Gel with enzymes targets set-in yellow stains

How to Whiten Yellowed Armpits on White Shirts

If you are already dealing with yellow underarm stains on white t-shirts, here are some ways to help whiten and remove the discoloration:

Bleach Soak

Make a diluted bleach bath by mixing 1 part bleach with 10 parts cool water. Soak the t-shirt for up to 30 minutes before washing normally. Check frequently to avoid over-bleaching. This can damage or ruin white cotton and linen fibers.

Baking Soda Paste

Make a thick paste of baking soda and water. Gently scrub it into the yellow stains using an old toothbrush or cotton swab. Let sit for an hour before rinsing and washing. Baking soda also helps deodorize as it lifts staining.

White Vinegar Rinse

Fill your washing machine rinse cycle with white vinegar or add 1/2 cup vinegar during an extra rinse. The acidic vinegar dissolves alkaline sweat and deodorant residues responsible for yellowing on white clothes.

Lemon Juice and Sunshine

Hand wash shirts in warm water with lemon juice, which acts as a natural bleaching agent. Hang in direct sunlight, as the sun’s UV rays also help whiten fabric. The combination of lemon acid and sunlight lifts discoloration.

Non-Chlorine Bleach

An oxygenated powder bleach alternative is less harsh but still effective on white shirt yellow stains. Add it to the wash cycle for a stronger bleaching effect than detergent alone. Look for types with sodium percarbonate.

Hydrogen Peroxide

Use a 3% hydrogen peroxide solution. Apply it directly to the yellowed area and let sit for 60 minutes before washing. Hydrogen peroxide provides gentle bleaching for white fabrics.

Home Remedies to Whiten White T-Shirt Armpits

If you want to avoid harsh bleach on yellow pit stains, there are some homemade and natural remedies you can try:

Borax Soak

Add 1⁄2 cup Borax powder to a basin of warm water. Soak shirts for 30 minutes to an hour before washing as normal. The mineral compounds in borax help lift staining and whiten fabrics.

White Vinegar Spray

Make a 50/50 mixture of white vinegar and water in a spray bottle. Lightly spray yellow underarm areas of the shirt until damp. Let sit for an hour before washing. The acetic acid in vinegar removes stain-causing residue.

Lemon Juice and Salt

Cut a lemon in half and dip the cut side in salt. Use it to gently rub the yellowed fabric. The citric acid acts as a bleaching agent and the salt provides an abrasive scrub. Rinse and wash as usual afterwards.

Grapefruit Juice

Soak the shirt in pure grapefruit juice for 2-3 hours before washing. The natural acids in grapefruit help break down yellow staining. This works best on minor discoloration.

Talcum Powder

Make a paste of talcum powder and water. Rub it into the stained underarms and let dry completely. The powder absorbs discoloring sweat and oil residue. Rinse the paste out and launder the shirt.

When to Discard a White T-Shirt with Yellow Stains

If a white tee develops stubborn yellowing that you cannot remove with whitening methods, here are some signs it may be time to retire that shirt:

  • Stains cover a large area, not just confined to the underarms
  • Shirt has thinning, threadbare fabric from repeated bleaching
  • Discoloration is affecting collar, sides or all over, not just the armpits
  • Yellowing has a brownish, dingy tone rather than just pale yellow
  • Odor persists even after washing and repeat stain removal attempts
  • You have owned the white t-shirt for many years of regular use

Natural aging and the cumulative buildup of sweat, body oils and deodorant chemicals over time will take a permanent toll on white cotton shirts. If the stains or wearing are extensive, discard the tee to keep your wardrobe looking fresh.

When to Toss Based on Extent of Yellowing

Yellow Stain Extent Time to Toss?
Small concentrated stains only under arms No, try stain removal techniques
Large yellow stains covering most of underarm area Yes, staining is too extensive
Yellowed collar or side seams, not just underarms Yes, overall shirt is yellowing
Dingy yellow-brown tone across fabric Yes, aging has permanently yellowed shirt

How to Prevent Future Yellow Stains When Buying New White Tees

When shopping for crisp white t-shirts, keep these tips in mind:

Choose Thicker, High Quality Materials

A medium to heavy weight cotton or cotton-poly blend will show stains less than a thin, lightweight knit. Pima, Peruvian or Egyptian cottons are luxurious options. Blends with polyester, modal or spandex will also resist yellowing.

Avoid Silk & Linen

Natural fabrics like silk and linen absorb sweat and will yellow more over time. Stick to cotton, synthetic or blended knits for white t-shirts.

Get an Oversized Fit

An oversized, looser cut allows more air circulation under the arms and puts less body oil and sweat directly onto the fabric. This reduces staining and yellowing compared to a fitted tee.

Select an Off-White Shade

Opt for an ivory, pearl or heathered pale grey rather than pure bright white. These shades hide yellow discoloration better over time. Darker armpits won’t stand out as much.

Apply Stain Resistant Spray

Treat new white tees with a stain resistant spray designed for clothing. This provides a barrier to protect the fabric from sweat and oils. Reapply it periodically.

Wear an Undershirt

Layering a snug tank or sleeveless undershirt under your white tee will absorb sweat rather than it reaching the outer shirt. Change just the underlayer to keep outer shirts fresher.

The Takeaway on Yellow Stains on White T-Shirts

To summarize why white t-shirt armpits turn yellow and how to stop it:

  • Sweat, deodorant chemicals, laundering, and aging all contribute to yellow discoloration under arms
  • Wash regularly and use laundry boosters to avoid set-in stains
  • Bleaching, stain pre-treatments, and natural acids can remove yellow stains
  • Buy thicker, oversized white tees in off-white shades to prevent future pit stains
  • Discard shirts with excessive yellowing that cannot be reversed

With diligent laundering and underarm care, your white tees can stay looking freshly bright. But some yellowing over time is inevitable. Embrace the lived-in, vintage look of a softened white t-shirt or replace it when those pesky pit stains become too pronounced.

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