Let's Talk About Yellow Pit Stains—And How to Clean 'Em

Most people sweat. Some more than others. During the summer especially, or in hotter climates, or while exercising, grocery shopping, and in stressful work meetings. Sometimes, you just sweat! Sweat is natural, and it has its own benefits, but armpit sweat also has some drawbacks. Namely: PIT STAINS. Paired with your natural deodorant, armpit sweat becomes a perfect storm—and ruiner of white baby tees and dress shirts. It happens to the best of us. But our Dirty Chemists are back at it, and they’re here with some solutions for you. Here’s how to clean up armpit sweat, laundry malodors and their accompanying stains.

Some Facts:

1. Underarm sweat is generated from the Apocrine Sweat Gland, which is made of a pocket of secretory tubules and an excretory duct that opens into a hair follicle. (OK!)

2. Apocrine sweat glands are inactive until puberty.

3. The sweat from the apocrine gland is a milky, oily fluid with proteins, lipids, carbohydrates, and steroids.  This milky, oily fluid is odorless before microorganisms find it as a food.

4. The sweat from the apocrine gland appears on the skin surface, and mixes with sebum, which comes from the sebaceous glands that open into the same hair follicle.

5. Sebum secreted by the sebaceous gland is primarily composed of triglycerides, wax esters, squalene, and free fatty acids.

6. Unlike sweat from the other body parts which secrete continuously, the apocrine and sebaceous glands underarm secrete in periodic spurts, with the amount and composition varying due to age, sex steroid levels, physical health and emotional conditions.

7. The body odors are mainly from the skin microorganisms’ actions on the excretions from apocrine glands (3) and sebaceous glands (5). The microorganisms take the proteins, lipids and sebum as food and drop out unsaturated short chain fatty acids that generate strong and unpleasant smells.

8. The microorganisms on male and female skins are different, so the resulting short chain fatty acids and related malodors are different for male and female armpits. This causes male armpits to give off of a rancid/cheese-like smell (Caproic acid), whereas female armpits give off a more fruity/onion-like smell (Ethanethiol).

9. The body odors generated by the excretions from underarm skin glands and microorganisms may carry unique genetic communications for sexual attractivity and family identifications.

Non-sweat contributions to pit stains.

11. Deodorants. These have typical ingredients including plant-based triglycerides (emollients), fragrances (masking odors), hydrocarbons (film former to seal the skin pores to slow down the sweat), and inorganic or organic water absorbers (to absorb sweat).

12. Antiperspirants. In addition to those typical ingredients used in deodorants, the active ingredients are aluminum and zirconium salts, which slow down or delay the excretions from the under-arm skin glands.

13. Underarm disinfectants and anti-inflammatory agents. The active disinfecting ingredients include triclosan and alkyl benzoate. Vitamins and other antioxidants are also used for anti-inflammatory effects against the infections caused by the bacteria within the underarm skin pores.

Armpit stains are..

A very complex mixture of:

a) The excretions from underarm skin glands
b) The body care ingredients applied to the underarm

Why are armpit stains so tough to remove?

These stains contain proteins, triglycerides, free fatty acids, hydrocarbons, carbohydrates, squalene, bacteria, bioactive steroids and hormones, and small unsaturated fatty acids that release malodors, and deodorants, antiperspirants and disinfectants. There is a lot going on there. They may interact with each other and get oxidized over time.

What are some effective cleaning solutions?

Enzymes: specifically designed to target the proteins, and triglycerides (oils and fats), carbohydrates, and phospholipids from the underarm skin gland sweat and sebum. Our Bio Laundry Detergents include a proprietary 5-in-1 blend of advanced enzymes to target the most complex stains. 

Oxygen booster: kills and removes bacteria and malodors, helps break down and remove steroids, cholesterol, squalene and organic metallic compounds showing yellow and brownish colors. We recently launched our Bio Enzyme Laundry Booster which includes an innovative new enzyme specifically designed to target "biological" stains, like sweat, blood, and sebum.