pH of Common Homemade Rinses

Science-y Hair Blog © 2011 by  Wendy M.S. is licensed under CC BY-NC-ND 4.0 

This post relates to a recent post about pH and your hair. It's best to stay between pH 4.5 and 7 under most circumstances.
Outside these limits of pH 4.5 and 7, hair is far more vulnerable to damage because it may swell rapidly and take the acid or base (alkali) into the hair, beneath the cuticle and this may damage proteins. It certainly removes some oils.

Homemade rinses are a fun, simple way to solve hair problems or try out ideas.
But acids and bases on hair can be damaging. The more resilient your hair (the lower the porosity), the less damaging a homemade rinse can be - but then again exposure to the wrong pH is one cause of hair damage. Most hair can withstand a slightly too-low or too-high pH for brief exposures. But if your hair is bleached, damaged, or otherwise especially vulnerable - even brief exposures to pH extremes can have lasting effects.

SAFETY NOTICE: Acid powders or crystals are eye, skin and respiratory irritants. Remove contact lenses, do not create dust, wash your hands immediately after using. If powders get in your eyes, rinse immediately with saline solution (tap water is okay, but uncomfortable). Keep acidic rinses or (alkaline solutions) away from your eyes, and away from children and pets.

The treatments:

Citric acid: Excellent rinse for helping reduce chlorine odor after swimming and to reduce hard water problems with hair.

• 1/8 teaspoon (0.6 ml) citric acid in 1 cup (230 ml) water = pH 3 
• 1/16 teaspoon (0.3 ml) citric acid in 1 cup (230 ml) water = pH 3.1 
• Stick with the lower amount of 1/16 teaspoon (0.3 ml) citric acid in 1 cup (230 ml) water or 1/16th to 1/8 (0.3 to 0.6 ml) teaspoon per 1 1/2 to 2 cups (350 to 475 ml) of water unless it does not give you the desired result. 

Even when you reduce the amount of acid by half the pH stays low. The 1/16th teaspoon has less free "acid" to react with your hair - it's less active - but the pH is still low and it's still quite reactive. 

©Science-y Hair Blog 2013

Ascorbic acid (Vitamin C): 

• 1/8 teaspoon (0.6 ml) ascorbic acid in 1 cup (230 ml) water = pH 3.6
• 1/16 teaspoon (0.3 ml) ascorbic acid in 1 cup (230 ml) water = pH 3.8
• Better to use 1/16th teaspoon (0.3 ml)  in 1 to 1 1/2 cups (230 to 350 ml), or 1/8 teaspoon (0.6 ml) in 2 cups (475 ml).

Acetic acid (vinegar): Vinegar can dissolve calcium carbonate - so vinegar rinses may help remove hard water deposits from your hair if hard water makes your hair rough and unruly. But getting enough vinegar to actually do that without going too low in pH may be difficult. 

• 1 tablespoon (15 ml) in 1 cup (230 ml) water = pH ~3.3 
• 1 teaspoon (5 ml) in 1 cup water (230 ml) = pH 3.7
• 1/4 teaspoon (1.25 ml) in 1 cup water (230 ml) = pH 4.5

Baking soda: Sometimes used to clean hair. When used as a laundry additive, it "softens" or at least alkalinizes hard water. Dirt and oil resist being washed away more by hard water than softened water.

• 1 tablespoon baking soda in 1 cup warm water = pH 8 

Bar soap: Well-cured bar soap lather is what I tested - that's a very old bar of real soap, lathered up in my hands.

• pH ~8 (too high)

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While short-term exposures to pH below 4 and above 7 may not be a problem for healthy hair, repeated or prolonged exposure is likely to cause damage to hair that cannot be reversed. Get some pH strips and test the pH of your homemade solutions!

This post has been updated as of March, 2015 using a more accurate pH meter.