Early hair relaxer products had a pH between 10 and 14, making them extremely alkaline. Most formulations fell in the range of 12 to 14, well above the threshold where permanent damage to both hair and skin begins. To put that in perspective, household bleach sits around pH 12 to 13, and drain cleaner is about 14. These early relaxers were chemically intense by any standard.
How the First Relaxers Were Made
The first hair relaxer was accidentally created in 1909 by Garrett Morgan, a tailor who was trying to reduce friction on sewing machine needles. He noticed that the chemical solution he was using also straightened the fibers of a fur cloth, and eventually tested it on hair. The key active ingredient in these early products was sodium hydroxide, commonly known as lye, mixed with water, petroleum jelly, mineral oil, and emulsifiers to form a cream. Manufacturers varied the sodium hydroxide concentration from 5% to 10%, which directly determined where the product landed on the pH scale.
At the lower end, a 5% sodium hydroxide solution produces a pH around 10. At the higher concentrations used in many early products, the pH climbed toward 13 or 14. There were no standardized safety guidelines in the early 20th century, so the exact pH depended entirely on the manufacturer’s formula and how much lye they added.
Why Such a High pH Was Needed
Hair relaxers work by breaking the chemical bonds that give curly or coiled hair its shape. The two most important bonds are disulfide bonds (strong links between protein chains) and salt bridges (weaker electrostatic connections). Research on hair fiber chemistry shows that a pH above 10 is the critical threshold where both types of bonds begin to break. Below that level, the alkali simply isn’t strong enough to penetrate the hair’s outer layer and reach the internal structure.
At pH 10, hair swells significantly and becomes more porous, allowing the chemical to penetrate deeper. Above pH 10, hydroxyl ions start permanently cleaving disulfide and peptide bonds inside the hair shaft. This is what actually straightens the hair: the internal protein structure is broken apart and then reforms in a new, straighter configuration as the hair is combed smooth during processing. The higher the pH, the faster and more completely this happens, which is why early manufacturers pushed the chemistry so far into the alkaline range. Speed and visible results mattered more than safety in those formulations.
The Damage That High pH Caused
A pH above 10 doesn’t just break bonds inside the hair. It’s corrosive to skin. Early relaxer users routinely experienced chemical burns on the scalp, ears, neck, and forehead. The same hydroxyl ions that straighten hair also dissolve the outer layers of skin tissue on contact, and the longer the product sits, the deeper the damage goes.
Even today, regulatory bodies like the Kenya Bureau of Standards set acceptable pH limits for relaxers at 11 to 13. That range is still high enough to cause burns with improper use, but it represents a narrower window than the essentially unregulated pH levels of early products. Early formulations at the top of the scale (pH 13 to 14) were especially dangerous because the pH scale is logarithmic: each whole number represents a tenfold increase in alkalinity. A product at pH 14 is ten times more alkaline than one at pH 13, and a thousand times more alkaline than one at pH 11.
No-Lye Relaxers Didn’t Lower the pH
Starting in the mid-20th century, manufacturers introduced “no-lye” relaxers using calcium hydroxide or lithium hydroxide instead of sodium hydroxide. These were marketed as gentler alternatives, and many consumers assumed they operated at a lower pH. They don’t.
A South African study that tested multiple commercial relaxers found no significant difference in pH between lye and no-lye products. Sodium hydroxide, calcium hydroxide, and lithium hydroxide relaxers all had statistically overlapping pH values. The same study found no pH difference between relaxers marketed for adults and those marketed for children, or between “regular” and “super strength” formulations. The active ingredient changed, but the alkalinity required to break hair bonds stayed the same. This makes chemical sense: regardless of which alkali generates the hydroxyl ions, the hair shaft needs the same pH environment to restructure.
The Role of Neutralizing Shampoos
Because all relaxers are strongly alkaline, every application requires a neutralizing step afterward. Early relaxers were rinsed and washed with soap that had been made with excess lye, which was not an effective neutralizer. Over time, manufacturers developed acidic neutralizing shampoos specifically designed to bring the hair’s pH back down toward its natural range of 4.5 to 5.5. This step stops the chemical reaction and closes the hair cuticle.
Skipping or rushing the neutralizing step was one of the most common causes of damage in early relaxer use. If the high-pH cream wasn’t fully removed and neutralized, it continued breaking bonds in the hair long after the intended processing time, leading to extreme brittleness, breakage, and scalp injury. Modern relaxer kits include dedicated neutralizing shampoos with pH indicators that change color to show when the hair has returned to a safe acidity level, a safeguard that simply didn’t exist in the early decades of relaxer use.