Pit stains are either armpit sweat and salt residue or sweat mixed with deodorant aluminium.

To remove:

- soak stain at least 10 minutes with undiluted distilled white vinegar, then wash with biological detergent.
- apply a paste of 3:1 ratio baking soda and water to the stain and rub it in with a brush, then wash as normal
- add 1/2 cup of baking soda with regular detergent to whiten, freshen, and soften fabrics.