Can I use the baking soda and hydrogen peroxide paste I use on cotton?

Skip peroxide on dyed polyester and stretch panels. It lightens color and can weaken elastane. On poly, baking soda plus dish soap, then a vinegar soak and enzyme wash, is enough for the yellow salts.

Will fabric softener get the sweat smell out of athletic shirts?

No. Softener and dryer sheets coat polyester and trap odor inside the knit. Wash without them and air-dry. If the pits still smell after one wash, repeat the vinegar soak before you use heat.

Guide

How to Remove Sweat Stains from Polyester Clothing

Turn the garment inside out, work a baking soda and dish-soap paste into the yellow pits (skip hydrogen peroxide on dyed polyester), soak in warm water with distilled white vinegar, then wash on warm with enzyme detergent and air-dry.

Polyester clothing Sweat stain

Context

Conditions that change the method

Color-sensitive — Hydrogen peroxide and chlorine bleach fade dyed polyester and weaken elastane. Keep the paste to baking soda and dish soap.
Delicate surface — Skip high-heat wash and dryer cycles. Heat sets yellow salts and odor in the fibers.

Do not mix vinegar with bleach, and do not use chlorine on yellow pits

Vinegar mixed with chlorine bleach releases irritating gas. Chlorine also turns sweat rings darker on polyester. If cleaner gets in your eyes or on skin, or you feel unsure or uncomfortable, rinse with cool water and get medical advice.

What you need

Baking soda
Dish soap
Distilled white vinegar
Liquid enzyme laundry detergent
A basin and warm water

Turn the shirt or jersey inside out so the underarm seams and deodorant crust face you.
Mix baking soda with a little dish soap and water into a thick paste. Do not add hydrogen peroxide — that is the cotton method and it lightens dyed poly.
Work the paste into the yellow, stiff pits with your fingertips for about a minute.
Soak the garment 30 minutes in warm water with 1/2 cup of distilled white vinegar.
Wash on a warm, gentle cycle with enzyme laundry detergent. Do not add fabric softener.
Air-dry. Check the pits and the smell before you use a dryer; leftover odor plus heat bakes it in.

What to avoid

Chlorine bleach on yellow underarm rings — it darkens them.
The cotton peroxide paste on colored polyester or stretch panels.
Fabric softener and dryer sheets; they coat the knit and trap odor.
A hot dryer while the pits still smell sour.

Products

What to use

Related guides

FAQ

Questions people ask

Can I use the baking soda and hydrogen peroxide paste I use on cotton?: Skip peroxide on dyed polyester and stretch panels. It lightens color and can weaken elastane. On poly, baking soda plus dish soap, then a vinegar soak and enzyme wash, is enough for the yellow salts.
Will fabric softener get the sweat smell out of athletic shirts?: No. Softener and dryer sheets coat polyester and trap odor inside the knit. Wash without them and air-dry. If the pits still smell after one wash, repeat the vinegar soak before you use heat.

Sources

Stain Removal Guide for Fabrics and Clothing — American Cleaning Institute
Learn About the Safer Choice Label — U.S. Environmental Protection Agency