Vinegar in the Wash

How can vinegar be a fabric softener?  It is basic high-school chemistry.  To review, what is the pH scale and what are acids and bases?  From the Chemistry Department at Elmhurst University   The pH scale measures how acidic or basic a substance is. The pH scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic.  Acids and bases neutralize each other.

What is soap?  Soap and bleach are bases, fabric softener and vinegar are acids. Rough fabric is from the residual build of soap, to neutralize this buildup you need an acid, both softeners and vinegar alter the pH of the water to act as an acid and remove the residual soap; either works great. pH of Downy is a 5, vinegar is a 4, neutral is 7. How you dispense is largely dependent on the pH of your tap water. On my front loader, a Kenmore HE3, essentially a Whirlpool Duet, after the wash there is a clean-water rinse, then the bleach cycle, then a final rinse. In the last rinse the fabric softener is dispensed. You can verify this yourself, during a cycle there is servo motor that moves a water director to shoot into the various dispenser compartments, pull the dispenser drawer during a fill cycle and see where the water is shooting from. According to Whirlpool, they wash-rinse-bleach-rinse because bleach is more effective in cold water and if it is not mixed with detergent. To mitigate the concern of acid remaining, I use the bleach cycle instead of the fabric softener dispenser. Using the bleach cycle to dispense the vinegar or fabric softener, you get two benefits; the washer -and- the fabric finish with a clean water rinse removing any latent soap/softener residue. For whites with bleach I put the vinegar in the fabric softener dispenser, the machine is designed for it anyway.

Know the pH of your tap water to most effectively clean your clothes, pick up some litmus paper. In San Diego the city adjusts the pH to slightly over 7, as do most municipalities, they do this is to prevent corrosion in metal pipes including copper, think Flint MI. If your water is acidic (below 7), use more soap, or an additive like Borax, to raise the pH of the water to clean better, then use less softener; flip if your water is an alkaline.

Bottom line: both vinegar and fabric softener are acids.