What is the Best pH for Your Hair?

woman checking the pH level of her hair care product

The concept of pH was introduced by the Danish chemist S. P. L. Sørensen at the Carlsberg Laboratory in 1909, according to the Science History Institute, and revised to the modern pH scale in 1924. In chemistry, these letters denote the potential of hydrogen or power of hydrogen and is a scale used to specify a water-like solution’s acidity or basicity. Basicity is the number of hydrogen atoms replaceable by a particular acid-base.

Understanding pH Numbers

The numbers on the pH scale range from zero to 14, and within that scale, zero to six represents the acidic side, seven denotes neutrality, and eight through 14 represents the alkaline end. It isn’t easy to understand what pH levels equate to in simple terms. These values vary slightly depending on their resource. Here are examples of everyday items, and the alkaline or acid number each one represents on the spectrum:

  • 0 – Battery acid
  • 1.0 – Hydrochloric acid/stomach lining
  • 2.0 – Lemon juice, lime juice, vinegar, gastric acid
  • 3.0 – Grapefruit juice, orange juice, colas, kiwi fruit
  • 4.0 – Tomato juice, acid rain, beer
  • 5.0 – Soft drinking water, black coffee, brown sugar, molasses, yogurt, banana
  • 6.0 – Urine, saliva, milk, salt, well water
  • 7.0 – Blood
  • 8.0 – Seawater, eggs
  • 9.0 – Baking soda, toothpaste, borax
  • 10.0 – Milk of magnesia
  • 11.0 – Ammonia Solution
  • 12.0 – Soapy water
  • 13.0 – Bleach, oven cleaner
  • 14.0 – Liquid drain cleaner, lye

Some of your client’s favorite salon services have their place on the pH scale too:

Temporary hair colors – Typically, found in the range of 7.0 to 8.0

Permanent hair colors – Permanent colors that use an oxidative process usually contain a pH range from 9.0 to as high as 11.0.

Shampoo – All shampoo pH values ranged from 3.5 to 9.0, though the ideal shampoo is 3.6 for your hair and 5.5 for your scalp.

Bleaches (oil) – Bleaches fall in the range of 8.0 to 9.0

Straighteners – Straighteners are very high in alkalinity, with their position on the pH scale anywhere from 11.0 to 14.

Acid Permanent Solution – Acid perms, gentler on the hair, contains a value of approximately 6.0 to 7.0 pH, similar to hair’s normal state.

Alkaline Permanent Solution – 8.5 to 9.5

What is the Best pH for Your Hair?

When the hair is at its peak of health, the pH ranges on the slightly acid side between 4.5 to 5.5. External chemical assailants such as bleaching, coloring, styling products, and shampoos disrupt the hair’s delicate balance. The disruption eventually causes the cuticles to lift, promoting frizz issues, breakage, and overall substandard hair health. Other external disruptors of the hair’s pH are environmental factors like air pollutants (including cigarette smoke), UV rays, humidity, and the water source utilized in your client’s daily hair care routine.

Why Is pH Important in Cosmetology?

Cosmetologists need to understand what effect pH has on the hair & scalp. This also includes knowing the pH level of the products you use on clients. When doing chemical services such as bleaching and coloring, you leave the cuticle scales exposed and in an alkaline state. A cosmetologist should contain the knowledge of the products that assist in closing the cuticles, bringing the hair back to an acid state.

Knowing The pH Terminology

Understanding chemistry, including pH talk, is vital for a cosmetologist. It is just as important to know how the right pH in a product or service improves the hair as it is to know how the wrong pH damages the hair. The first step in getting familiar with the world of pH is knowing the correct terminology.

Here are just a few terms you’ll learn when you reach the pH part of your cosmetology curriculum:

Acidic solution – an acidic solution contains a pH below 7.0 (neutral).

Alkaline solution – an alkaline solution contains a pH above 7.0 (neutral).

Alkalis (bases) – the hydroxides of a compound that neutralizes acids to form salts.

Acid – the hydrogens of a compound that neutralizes alkalis.

pH paper (litmus) – a piece of paper containing a chemical indicator that changes color based on a solution’s ion level.

Logarithm – the pH scale is logarithmic, meaning each tik mark on the scale is a tenfold increase in alkalinity or acidity. For instance, a hydrogen ion level at 4.0 is ten times greater than 5.0.

Neutral solution – a neutral solution contains equal numbers of H+ and OH- ions = 7.0.

Strong acid – a strong acid contains a high concentration of H+ ions pH 0-3.

Strong base – a strong base is an acid with a high concentration of OH- ions pH 11-14.

Disruption in The Hair’s pH Balance

When the hair is at the proper pH level, the cuticles are tightly closed, giving hair a healthy, smooth feel and a shiny appearance. Helping your client maintain their hair and scalp’s natural pH level helps their scalp’s acidic sebum fight bacteria. If this balance gets disrupted with a product that’s too high in alkalinity, the cuticles open up, causing hair issues. Using a heavy acidic product causes the cuticles to contract, making hair resistant to services like permanent coloring where the color needs to reach beneath the cuticles. When the hair repeatedly goes through changes in pH and the cuticles continuously swell and close, the hair experiences Hygral Fatigue.

Testing and Balancing the Hair’s pH

Testing the hair’s pH is simple using test paper, otherwise known as litmus strips. Litmus strips are available at beauty supply stores and change color depending on the hair’s pH scale level.

If your client’s hair is out of balance, don’t worry; bringing it back is simple; suggest a few natural at-home routines that include putting their haircare routine in check. Suggest they check labels on their favorite hair care products, from shampoos to finishing sprays. Have them avoid any product that contain a pH that is not within a range of 4.0 to 7.0. Once you bring your client’s hair back to its natural, acidic form, it is time once again to maintain the best pH with the suggestion of the right hair care products.

Don’t Forget About the Scalp’s pH

Not only the actual hair’s pH balance plays a vital role in natural overall hair health, but the scalp scale does too. The science of your client’s scalp pH is crucial to achieving the optimal outcome of salon services, from their dry to itchy scalp, hair growth, and how their hair reacts to various chemical and non-chemical products. These are the four reasons why balancing your client’s scalp’s pH matters for healthy hair growth.

Reason #1 – Protects Hair from Bacteria and Fungus

A healthy pH balance is a protective barrier that helps fight bacteria-causing fungus. The proper pH balance prevents unwanted breakage, seals the hair cuticles, maintains moisture and natural oils. Typically, the hair’s pH balance lies between 3.6 to 5.5, with the usage of fewer alkali products helps maintain acidity.

Reason #2 – Balanced pH Determines How Products Work on Your Hair

Using shampoos, conditioners, and other products on the hair affects the pH balance. Products that contain more alkali will cause the hair follicles to expand and release needed moisture. The loss of moisture stunts hair growth and causes it to become brittle, dry, and frail. It is crucial to use products that work in conjunction with each other to remove dirt and buildup without stripping vital moisture it needs to thrive. Suggest that your client avoids products that include Triethanolamine and Sodium hydroxide, high in alkali with a level over 7.0.

Reason #3 – Helps Maintain Hair’s Elasticity

pH goes hand in hand with the hair’s ability to hold moisture and maintain its sebum. Sebum is the hair’s natural conditioner and protective shield responsible for retaining moisture. Water is what gives your hair the ability to bend and not break during manipulation. When your hair loses its moisture, it becomes dry and prone to breakage. Remember to keep your client’s hair moisturized, as it is vital to their hair elasticity and natural hair growth.

Reason #4 – Reduce Risks of Breakage Due in Part to Chemical Services

The hair is susceptible to changes. Anything that throws off your client’s body pH throws off the balance that affects their hair’s ability to retain its strength and responsiveness to other hair care products. Chemical treatments such as dyes and relaxers alter your client’s hair pH and weakens protein structure, ultimately causing dry, brittle hair stunting hair growth. Stunted growth occurs when a sudden change happens to the client’s pH balance and increases alkalinity.

Final Thoughts

When deciding to perform a cosmetology service, consider your client’s hair pH balance and its behavior to services beforehand. Knowing the chemistry behind your client’s hair helps the services you provide result in their very best for the client. Life is about balance, both body and mind.

Cosmetology Program

At Minnesota School of Cosmetology, we are dedicated to helping our Cosmetology program students develop a solid foundation and a flair for style through hands-on training in basic and advanced industry techniques. You will learn how to cut, color and style hair, give manicures and pedicures, provide spa treatments and perform various skin care techniques from industry-experienced instructors in a professional salon setting.

Contact us today to learn more about becoming a cosmetologist and starting a rewarding career in the beauty industry.