What historical chemicals were used in hair straightening?

Roots

From the earliest whisperings of human adornment, hair has held a quiet, yet profound, power. It speaks of lineage, of spirit, of self. For as long as strands have sprung from scalp, there has been a curious human inclination to alter their natural inclination, to coax them into new forms, often seeking a smoother, straighter cascade. This yearning, ancient and persistent, laid the groundwork for a chemical saga, a story etched not just in laboratories, but in salons, homes, and personal narratives across generations.

Early Alterations of Hair’s Natural State

Before the advent of complex chemical formulations, humanity turned to simpler means to reshape hair. Ancient civilizations, including those in Egypt and Rome, employed heated tools to achieve a straightened appearance. Early methods involved hot combs crafted from heated metal rods, passed through sections of hair to temporarily relax its natural pattern.

This physical manipulation, while effective for a time, did not permanently alter the hair’s inherent structure. Oils and greases often accompanied these heated implements, aiding in glide and providing a temporary sheen, yet offering no lasting chemical change.

In the late 19th and early 20th centuries, figures such as Madame C.J. Walker popularized and refined the use of the hot comb in African American communities. Her work centered on hair care and growth, and while she used hot combs with wider teeth and topical lotions, the primary mechanism of straightening remained thermal.

These early pressing methods relied on the temporary breaking of hydrogen bonds within the hair’s keratin structure, bonds that would reform once moisture was reintroduced, causing the hair to revert to its natural curl pattern. The pursuit of straightness, therefore, was a recurring effort, a constant reapplication of heat and product.

The Genesis of Chemical Intervention

The landscape of hair alteration shifted dramatically with the accidental discovery by Garrett Augustus Morgan in 1909. While seeking a solution to ease friction on sewing machine needles, he observed that a chemical lubricant he created had a surprising effect on wool fabric, causing it to straighten. His curiosity led him to test this concoction on an Airedale dog’s fur, and then on his own hair, yielding similar straightening results.

This discovery marked the true beginning of chemical hair straightening. Morgan, an African American inventor, soon established the G.A. Morgan Hair Refining Company, marketing his “hair refiner” cream primarily to Black and mixed-race individuals. His early formulas contained alkaline products, reflecting the common use of lye in soaps of that era.

This innovation represented a profound shift, offering a more lasting alteration to hair’s curl pattern than heat alone. It promised a new ease of styling, a liberation from daily thermal efforts, and a pathway to a widely accepted aesthetic.

Societal Currents and Beauty’s Shifting Sands

The introduction of chemical straighteners was not merely a scientific advancement; it arrived amidst powerful societal currents. For Black women, particularly in the early 20th century, hair texture became intertwined with perceptions of respectability, professionalism, and social acceptance. In a society that often favored Eurocentric beauty standards, straight hair was frequently seen as a prerequisite for assimilation and upward mobility. This created a compelling, sometimes overwhelming, pressure to conform.

The desire for straight hair, driven by cultural norms and perceived societal acceptance, spurred the early adoption of chemical treatments.

The market for hair straightening products grew rapidly, disproportionately targeting Black women and girls. The widespread marketing of these products, promising “manageable” hair and a path to conventional beauty, deeply embedded chemical straightening into the fabric of many communities. This historical context reveals a complex interplay of innovation, aspiration, and the sometimes-unseen pressures that shape personal choices regarding appearance.

Ritual

Moving from the deep currents of historical longing, we arrive at the very hands-on practices, the intimate moments of transformation that shaped hair. The quest for straightness, once a whispered wish, found its voice in tangible routines, in the precise mixing of compounds, and the careful application of heat. These were not mere steps; they became rituals, often laden with anticipation and a distinct aroma, each one a testament to the persistent human drive to redefine texture.

The Era of Lye’s Potent Reign

The commercial production of lye relaxers officially began in 1917, with companies like Proline leading the way. The active ingredient in these powerful formulations was Sodium Hydroxide, commonly known as lye. This strong alkali worked by a process called lanthionization, which permanently broke the disulfide bonds within the hair’s cortex layer. These bonds are responsible for the hair’s natural curl pattern, and their breakage allowed the hair to be reshaped into a straight form.

A typical lye relaxer formulation consisted of sodium hydroxide mixed with water, petroleum jelly, mineral oil, and emulsifiers to create a creamy consistency. While highly effective at straightening even the tightest curls, lye relaxers came with significant risks. The high pH level (typically 11.5 to 14) meant they were extremely caustic.

Scalp burns, irritation, and hair damage were common occurrences, leading to widespread complaints. Despite these known hazards, the allure of straight hair often outweighed the immediate discomfort and potential long-term harm.

The Emergence of “No-Lye” Formulations

In response to the growing awareness of the dangers associated with lye-based relaxers, manufacturers began seeking milder alternatives. The late 1970s and early 1980s saw the introduction of “no-lye” relaxers. These products replaced sodium hydroxide with other alkaline agents, most notably Guanidine Hydroxide. Other chemicals like Potassium Hydroxide, Lithium Hydroxide, and Calcium Hydroxide also appeared in these formulations.

While marketed as gentler, “no-lye” relaxers were not without their drawbacks. They often required mixing an activator into the formulation to initiate the chemical reaction. A significant issue with guanidine hydroxide-based products was the tendency for calcium deposits to form on the hair shaft.

This buildup could leave the hair feeling dry, brittle, and dull, necessitating the use of chelating shampoos to remove mineral residues. So, while the immediate scalp irritation might have been reduced for some, a different set of challenges for hair health presented itself.

What are the Distinct Actions of Thio-Based Straighteners?

Beyond the hydroxide-based relaxers, another family of chemicals, the thioglycolates, gained prominence, particularly with the rise of Japanese straightening or thermal reconditioning in the late 1990s and early 2000s. These “thio relaxers” primarily use Ammonium Thioglycolate (ATG). Unlike the hydroxides that disrupt the entire protein structure, ATG works by selectively weakening the hair’s cystine bonds (disulfide bonds) through a reduction process.

The process with thio-based straighteners typically involves applying the chemical solution, allowing it to soften the hair, and then meticulously straightening the hair with heated flat irons. This combination of chemical action and mechanical heat helps to reshape the hair’s internal structure. Following the heat application, a neutralizer, often hydrogen peroxide, is applied to re-form some of the bonds, setting the hair in its new, straight configuration. While offering a long-lasting straightness and frizz reduction, these treatments could still be harsh and time-consuming if not performed correctly.

The Early Days of Keratin Treatments

The early 2000s witnessed the emergence of keratin treatments, often known as Brazilian Blowouts, which promised smoother, frizz-free hair. The initial formulations of these treatments relied heavily on Formaldehyde or formaldehyde-releasing agents, such as Methylene Glycol. The mechanism involved formaldehyde forming cross-links with the keratin amino acids in the hair, and the subsequent application of a heated flat iron further enhanced this cross-linking, effectively “freezing” the hair in a straight position.

These early keratin treatments were highly effective, sometimes lasting for several months. However, the high levels of formaldehyde (ranging from 9-15% in some original compositions) released unpleasant fumes and posed significant health risks, particularly respiratory issues, for both clients and salon workers. This led to later efforts to reduce or eliminate formaldehyde from formulations, replacing it with alternatives like glyoxylic acid, though these often provided less permanent results.

Relay

Beyond the individual application, beyond the immediate transformation, lies a deeper, more intricate layer of understanding. To truly comprehend the story of hair straightening chemicals, one must peer into the molecular dances they orchestrate, and simultaneously, gaze outward at the vast societal currents that amplified their influence. This section seeks to unravel the complex interplay between chemistry, commerce, and the compelling human desire for belonging, often expressed through the very texture of one’s hair.

How Do Hair Straightening Chemicals Alter Hair Structure?

At the microscopic level, hair’s strength and shape are largely determined by its protein structure, particularly the disulfide bonds that link keratin chains. These bonds provide hair with its natural elasticity and curl. Chemical straighteners work by disrupting these strong bonds, allowing the hair to be physically re-formed into a straighter configuration. Hydroxide relaxers, such as those containing Sodium Hydroxide or Guanidine Hydroxide, achieve this through a process called lanthionization.

This involves the removal of a sulfur atom from the disulfide bond, creating a new, irreversible lanthionine bond. This permanent alteration accounts for the lasting straightening effect.

Thioglycolate-based straighteners, on the other hand, operate through a different chemical pathway. Ammonium Thioglycolate acts as a reducing agent, breaking the disulfide bonds. Once the bonds are broken, the hair is mechanically straightened with heat, and then an oxidizing agent, typically hydrogen peroxide, is applied to re-form new disulfide bonds in the hair’s new, straight shape.

This re-bonding step is what makes the straightening permanent until new growth appears. The subtle differences in these chemical actions lead to varying degrees of straightness, longevity, and potential for hair damage.

Unseen Chemicals and Health Consequences

While the primary active ingredients are well-known, many historical and even contemporary hair straightening products contained, and sometimes still contain, a cocktail of other chemicals. A significant concern revolves around Endocrine-Disrupting Chemicals (EDCs), which can interfere with the body’s hormonal balance. These include parabens, phthalates, and, notably, Formaldehyde or its releasing agents. The presence of these substances, often absorbed through the scalp, has raised serious health alarms.

The disproportionate impact of these chemicals on Black women is a deeply concerning aspect of this history. Historically, chemical hair relaxers have been heavily marketed to and widely used by Black women and girls, often starting at very young ages. This prolonged and frequent exposure has led to significant health disparities. Research from the National Institutes of Health (NIH) and Boston University’s Black Women’s Health Study provides compelling evidence of these links.

Long-term use of chemical hair straighteners has been linked to increased risks of hormone-related cancers, disproportionately affecting Black women due to historical usage patterns.

For instance, the landmark Sister Study , published in October 2022, revealed that women who frequently used chemical hair-straightening products, a majority of whom were Black women, were Two and a Half Times as Likely to Develop Uterine Cancer. Further findings from the Black Women’s Health Study indicated that Black women who used lye-based hair products at least seven times a year for 15 or more years had an approximately 30 Percent Increased Risk of Estrogen Receptor Positive Breast Cancer compared with less frequent users. Moreover, a 2023 study from Boston University suggested that Black women who used relaxers more than twice a year or for over five years had a 50% Increase in Uterine Cancer Risk. These studies highlight a concerning correlation between chemical hair straightener use and adverse health outcomes, including uterine fibroids, ovarian cancer, and early onset puberty.

The precise mechanisms by which these chemicals contribute to such health issues are still being investigated, but their endocrine-disrupting properties are a key focus. They can mimic or interfere with natural hormones in the body, potentially altering estrogen-dependent pathways and leading to the development of tumors. The ongoing litigation against manufacturers reflects the growing body of evidence and the severe consequences experienced by many individuals.

Societal Pressures and the Quest for Belonging

The prevalence of chemical hair straightening, especially among Black women, cannot be understood solely through a chemical lens; it is deeply intertwined with societal pressures and the complex quest for belonging. For generations, straight hair was presented as the standard of beauty and professionalism, particularly in Western societies. This created a powerful incentive to alter natural hair textures, often at significant personal cost.

• Assimilation ❉ Historically, straightening hair was a means for Black individuals to assimilate into dominant white cultural norms, believing it would lead to greater acceptance and opportunities.
• Professional Expectations ❉ In many professional environments, textured hair was, and sometimes still is, perceived as “unprofessional,” pushing individuals toward straightened styles for career advancement.
• Self-Perception ❉ The constant messaging from media and society could internalize a preference for straight hair, influencing self-esteem and identity development from a young age.

The narrative surrounding “good hair” versus “bad hair” has had a lasting psychological impact, contributing to a cycle of chemical use that, for many, began in childhood. The CROWN Act, enacted in some regions, represents a contemporary effort to combat discrimination based on race-based hairstyles, signaling a societal shift toward celebrating natural hair. This movement encourages a deeper understanding of hair’s diverse forms and a move away from harmful beauty ideals that once dictated the widespread use of potent chemicals.

Reflection

The journey through the history of chemical hair straightening reveals a landscape far richer and more complex than simple cosmetic preference. It is a narrative interwoven with scientific discovery, profound cultural shifts, and deeply personal experiences. From the earliest alkaline concoctions to the sophisticated formulations of today, each chemical step has left its mark, not only on hair fibers but on health, identity, and societal norms. The quest for straightness, once a silent aspiration, became a tangible ritual, often performed with a hopeful heart, yet sometimes yielding unforeseen consequences.

Understanding this past allows us to stand in a more informed present, where choices about hair care can be made with a clearer view of both chemistry and context. It prompts us to honor the inherent beauty of all textures and to champion a future where personal expression through hair is unburdened by historical pressures or hidden risks.

References

• Department of Toxic Substances Control. Chemicals in Hair Straightening Products Background Document. 2021.
• Wikipedia. Relaxer. Accessed May 23, 2025.
• Martines, Buffy. Hair Relaxers and Health ❉ Unveiling the Hidden Risks of Chemical Hair Straighteners. Accessed May 23, 2025.
• Drugwatch.com. Health Impacts of Chemical Hair Relaxers. Accessed May 23, 2025.
• Mcdowell, Ronisha. The History of Chemical Relaxers. Prezi. Accessed May 23, 2025.
• Synonym. The History Behind Hair Relaxers. Accessed May 23, 2025.
• The Impact of Hair Relaxer Lawsuits ❉ Unveiling the History and Harmful Chemicals. Accessed May 23, 2025.
• Stay Current Florida. Relaxer Theory. Accessed May 23, 2025.
• Vitale Pro. The Evolution of Hair Relaxers ❉ What’s New in 2024? Accessed May 23, 2025.
• Biopulent. The Evolution of Hair Straightening ❉ From Chemical Solutions to Nanoplasty. Accessed May 23, 2025.
• The Evolution of Hair Straightening Techniques. Accessed May 23, 2025.
• The Commonwealth Times. The oppressive roots of hair relaxer. 2011.
• FullyVital. Formaldehyde ❉ Unveiling The Science Behind Hair Growth. 2023.
• Kera Mane. The Evolution of Safer Keratin Treatment Ingredients ❉ Advancements for. 2024.
• Hair fashion trends and formaldehyde health risks. Accessed May 23, 2025.
• Why are chemical hair straighteners and relaxers primarily marketed to Black women? Accessed May 23, 2025.
• Chemical/Straightening and Other Hair Product Usage during Childhood, Adolescence, and Adulthood among African-American Women ❉ Potential Implications for Health. Accessed May 23, 2025.
• Straight to the Point ❉ What Do We Know So Far on Hair Straightening? PubMed Central. 2021.
• WFAA. Damage Control ❉ The studies that sounded the alarm on chemical hair relaxers. YouTube. 2025.
• PBS News. 25-year-long study of Black women links frequent use of lye-based hair relaxers to a higher risk of breast cancer. 2021.
• Keratin treatment history. Accessed May 23, 2025.
• BR KERATIN. The history of the origin of Brazilian keratin. 2022.
• ResearchGate. “I Remember My First Relaxer” ❉ Black Women Voicing Psychologically Engrained Practices of Chemical Hair Straightening. 2024.
• Eric Fisher Academy. The History of the Flat Iron ❉ A Staple Tool in Cosmetology. 2022.
• The Swaddle. Hair Straightening Chemicals Were Linked With Cancer – Showing the Dangers of Beauty Norms Around Hair. 2022.
• PubMed Central. Hair relaxer use and risk of uterine cancer in the Black Women’s Health Study. 2023.
• Harvard T.H. Chan School of Public Health. Uncovering the dangers of hair products marketed to Black women, girls. 2024.
• NewYork-Presbyterian. What to Know About the Connection Between Hair Relaxers and Uterine Cancer. 2024.
• The Serious Health Risks of Hair Relaxers. Accessed May 23, 2025.
• Motley Rice. Are Hair Relaxers Safe? What to Know About Cancer Risks. 2025.
• Design Essentials. Knowing Different Types of Hair Relaxers. Accessed May 23, 2025.
• hairdresser injury support and information. Chemical Straighteners / Relaxers. Accessed May 23, 2025.
• Frontiers. Chemicals of concern in select packaged hair relaxers available on the Kenyan market ❉ an examination of ingredient labels and measurement of pH. 2025.
• Hairlicious Inc. Hair Question ❉ Lye vs. No Lye Relaxer – The Difference + Pros and Cons. 2017.
• Florida Academy. Permanent Hair Straightening Treatments ❉ Pros, Cons and Side Effects. 2020.
• Google Patents. Hair conditioning composition comprising ammonium thioglycolate and/or ammonium thiolactate. Accessed May 23, 2025.
• Black Skin Directory. Hair Relaxers, Cancer Risks and Black Women’s Health. 2025.