Thursday, August 15, 2013

pH of Common Homemade Rinses

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.

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)
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. 


  1. I am so grateful for this information! I started going no poo because the detergents in the shampoos were irritating my skin; it really had nothing to do with my hair. As I was trying baking soda, soap, vinegar rinses, etc., and reading all the crazy stuff that's out there on the web regarding no poo alternatives, I kept thinking that I was shooting in the dark. I had no idea what I was doing to my hair over the longer term, and my suspicion that I was on the road to ruin was probably true. This post of yours was my introduction to a more scientific, pragmatic way to take care of my skin without sacrificing my hair. I've gone back to shampoo, but well-diluted as discussed in another of your blogs ,and my skin so far is ok. Thank you so much for sharing your knowledge in this very very informative blog! I love reading your entries and seeing how they evolve over time!

  2. Dear WS, thank you so much for lots and lots useful information about hair.
    There are so much to learn about every part of our body. Still in the going into organic journey, but somehow i think the environment i am living is just not possible to go full on organic.

    Anyways, every since I went no poo (before, now i use shampoo), my scalp becomes very very dry. Even i do oiling before shampoo, as soon as my scalp dries, i can see flakes on it already. I was just wondering if there are anything i can put on scalp other than oil, like moisturizer for face, but for scalp?

    I found that vinegar rinse can help prevent hair odor as well, thanks for the tips.

    1. Hello Ell,
      It sounds like your scalp became irritated when you went "no-poo." I don't know whether by "no-poo" you mean you used baking soda to wash your scalp and hair or you mean you used conditioner to wash your scalp. The same term is used for both.
      Either way, when the scalp becomes irritated and inflamed, the skin breaks down. Skin has several layers of defense against the environment and when that defense breaks down, the skin becomes dry (or oily), flaky, feels tight or itchy or stings. There is a good visual aid in this post to show you what has happened:
      You may need to use a medicated shampoo or medicated treatment for a while to help your scalp along in the healing process. I have a long list of those in the tab (top of the page) labeled "Products for Itchy, Flaky or Bumpy Scalps."
      There are some moisturizers you can use on your scalp. Some will work as a "rinse" for your hair too, but others you'd want to apply with a cotton ball so your hair doesn't end up looking odd. For some scalps, aloe is a good moisturizer. I would want to use aloe vera juice (Lily of the Desert, for example) with as few preservatives as possible and dilute it with water at least 50:50, maybe more like 1 part aloe, 3 parts water. That might be a good rinse for hair or a spray. Witch hazel (not the kind with alcohol) can be a good moisturizer (humectant).
      You can make a scalp-soothing rinse with calendula flowers (make like a tea, but steep for 30 minutes).

      You may need to change shampoos, too. Some shampoos have irritating ingredients and will cause flaking. There are tips on the "Itchy Scalp" product page for choosing shampoos.

      Any of the usual medicated treatments for dandruff can be helpful. Ketoconazole, pyrithione zinc and salicylic acid all work in various ways to help create a condition in which the scalp can heal more quickly so it isn't so dry and flaky.
      Good luck! I hope your scalp feels better soon.

  3. Is there any harm in applying rinses like citric acid with a spray bottle beforehand, and letting it set in/dry before getting into the shower...?

    1. I'm not sure what the reason for doing this would be, so I'm not sure I'm answering the right question. Once a liquid is dry, it ceases to have a pH level - pH is something only liquids can have. You need those free H+ and OH molecules and that happens in solutions only.
      In order to be careful about not damaging hair, it's probably best to time the use of the rinse when your hair is already wet, leave it on for a fixed amount of time and then rinse it off or squeeze-dry to remove excess. If you saturate dry hair with a liquid with a rather high or rather low pH, there is no water on the hair to buffer the pH of the rinse and it will be forced to stay in the liquid until it dries naturally. If that were pH 9 or pH 3, one might have some unpleasant side effects from long-time exposure.

  4. Hi WS. Thank you for your long message to my comment. I have finally given up on being "organic" because i think the environment, the water that I am living is not for organic. I have been using medicated shampoo mainly and diluted shampoo as a change sometime. I released I need to watch more often to keep the dry flakes at bay (once in every 2 days).
    Anyways, think you for the articles, they are amazing!! Not all organic stuff is good for my skin, I have to find the one that suits it.

    Wish you all the best!

  5. So something like Black soap and Paypaya soup have too high of a PH for the skin?
    Can you tell me if the PH of Witch hazel and Braggs ACV? I normally do 1 tbl of ACV and 2 TBL of witchhazel but i dont know if this is the right PH .

    1. Hello Kai,
      Any soap made with sodium hydroxide or potassium hydroxide and oils will have a pH that is higher than is ideal for skin. If your skin is healthy - that may not be a problem. But it can be irritating for sensitive or dry skin. For hair, soap is outside the pH range at which hair is most resilient to damage - but lower porosity hair tends to be less affected by soap than porous hair.
      I don't know the pH of witch hazel - it would depend on the product. Bragg's vinegar is 5% acidity, so the pH should be the same as the ACV I tested when used in the dilutions in the vinegar section - I started at 1 tablespoon per cup of distilled water. If you're using vinegar at 1 part vinegar, 2 parts witch hazel, that's probably a pH of 3.

  6. Hi,just want to clarify. For the acv ratio don't you mean 1/4tsp to 1/2 cup of water?

    1. For the pH reading, I used 1/4 teaspoon in 1 cup water.

  7. Hi WS. What should be the ph of a daily moisturizing spray or spritz? And do you have a recipe?

    1. The pH should be between 4.5 and 6. But the pH won't be an issue once the sprits is dry. Only solutions have pH values. I don't have a specific recipe, but distilled water is a great base, conditioner tends to mix well with water, and humectants like aloe vera or glycerin are good.

  8. Thank you for sharing your wealth of information. After reading several of your blogs I decided to do a pH test on the products I currently have been trying to use. To my surprise, my shampoo I recently purchased & starting using the pH is way too high. I first tried it & my hair felt great but then th second time it made my hair very dry. I am honestly frustrated as I am not sure what to do with my hair. I was doing a method about a year ago & I think it messed up my hair. My scalp is irritated & itches quite often every time before & after a wash. My hair is currently damaged by a few factors 1) very hard water from where I was living & 2) the method I was using that I found on YouTube. I use to have very thick hair & very moisturized now my hair is thin, limp, dry, breaking and not very elastic. I have tried so many products but nothing appears to work except the things I make at home & kinky curly custard & knot today. I seem to have frizzy hair at th roots that appears to be a different texture than from mid shaft to tip. I honestly don't know what to do & need help. Do you have a suggestion as to what I may be able to do to get my hair back on track? Thanks in advance for your assistance.

    1. Hello MsNaturaltruth,
      I'm sorry you're having such a hard time with your scalp and hair. It sounds like you have an underlying scalp condition - I know that's stating the obvious. But it would help to know whether you're having a reaction to products (contact dermatitis) or whether the things you used caused a flare-up of something like eczema or atopic dermatitis. Sometimes those 2 go together.
      The first priority is to get your scalp healthy. Seeing a dermatologist would be ideal. If that's not possible or you want to rule out some inexpensive options first, you might try one of the medicated treatments you can buy over the counter for the itching. Click the tab for "Products for Itchy, Bumpy of Flaky Scalps" at the top of the blog and you'll find a list of medicated products. Read reviews for the products, ask family members their experiences - try to narrow the field a bit.

      Irritated and itchy scalps and increased hair loss go together, so that issue needs to be dealt with.
      If it helps to go back to whatever you used to use before you experienced these problems - that's a good start. Sometimes once our scalps become irritated, even old, tried-and-true products can cause irritation.

      Kinky Curly Custard and Knot Today are good products. I don't know what else you're using or what you've tried or what you make at home. If hair is losing elasticity, hard water can be a problem if you have that. And good ingredients for improving elasticity are panthenol (humectant), honey (humectant) or hydrolyzed proteins (also humectants) in conditioners or styling products. Protein isn't right for everybody. For preventing dehydration - oil pre-wash treatments with hair-penetrating oils (avocado, olive, sunflower, coconut, babassu).

      Oil on the scalp might be something to avoid when you have itchy scalp. For some of us, oils on the scalp over-feed the yeasts on our scalps, or create irritation and cause more itching. I hope that helps! W