It’s hard to imagine that the principles of perming hair and steaming buns are the same?

The Spring Festival is coming soon. For many people, manicures and perms are inevitable. Perms can not only change your hairstyle, but also completely update your overall image. From tinfoil perms to big waves, each perm style can convey a different personality and atmosphere. Perms can make you look more fashionable, mature or energetic, and can also provide a good choice for those who want to change their mood.

You may be curious about what the perming process is like and whether it will affect the health of your hair. Let’s explore the structure of hair, uncover the scientific principles of perming, and its effects on your hair and scalp.

Hair composition and structure

Hair is mainly composed of a protein called keratin, which accounts for about 95% of the total weight of hair. Keratin is a type of hard, water-insoluble fibrous protein that is widely found in humans and other animals, such as skin, nails, feathers, hooves and claws.

Keratin molecules are composed of many amino acids, which are connected together by peptide bonds. You can imagine each amino acid as a pearl in a pearl necklace, and the peptide bond is the rope connecting every two pearls. However, the structure of protein is not like a pearl necklace hanging around the neck, but like a pearl necklace stacked together.

Keratin contains a lot of sulfur-containing amino acids such as cysteine. When amino acids are "stacked together", this allows them to connect through the formation of disulfide bonds. A disulfide bond is a chemical bond between two sulfur atoms, usually between two cysteine ​​residues in proteins. In hair, feathers and nails, the presence of disulfide bonds makes the structure of keratin more solid, and it is these disulfide bonds that maintain the natural shape and elasticity of hair.

Amino acids are like pearls, peptides are like short pearl bracelets, and proteins are like long, stacked pearl necklaces (Source: Generated by the author using AI)

The structure of a hair is not as simple as it looks to the naked eye. In fact, each hair consists of three main parts: the cuticle, cortex and medulla. The cuticle is the outermost layer of the hair and is composed of multiple layers of flat cells that overlap like fish scales to protect the internal structure.

The cortex is located within the epidermis and is the main body of the hair. It contains a large amount of keratin and pigments, which determine the strength, elasticity and color of the hair. The medulla is the central part of the hair. Although not all hair has medulla, it is usually related to the strength and elasticity of the hair. These three parts together constitute the complex and delicate structure of the hair.

Schematic diagram of hair cross section (Source: drawn by the author)

By understanding these basics, you will be able to better understand the principles of perming and its effects on health.

What are the principles of perming?

Perming is actually a chemical and physical process to change the shape and structure of hair. Specifically, perming works by affecting the keratin in the hair. Remember the disulfide bonds mentioned above? Perming is actually a process of "disassembling" and "reorganizing" disulfide bonds.

We just mentioned that the disulfide bonds in keratin maintain the natural shape and elasticity of hair. In the initial stage of perming, a reducing agent (usually containing a thiol-producing chemical) is used to break the disulfide bonds in the hair. This step makes the hair "plastic" or "remodelable". Curling and shaping: After the reducing agent is applied, the hair is wrapped around the curling iron to form the desired new shape. Finally, some oxidizing agent is applied to reform the disulfide bonds, thus fixing the hair in the new shape.

Perming is actually a process of "disassembling" and "reorganizing" disulfide bonds

The most commonly used chemicals in this process are ammonium sulfate and glycerol sulfate. The breaking and reforming of disulfide bonds is achieved through a chemical reaction called "reduction," which involves the addition of hydrogen. In a standard "cold" perm, the hair is curled and the reducing agent ammonium sulfate is added, which then breaks the disulfide bonds and allows the keratin molecules to move freely and take on the shape of the curl. Finally, a "neutralizer" such as hydrogen peroxide is added to reverse the effects of the reducing agent.

Cold perm: uses a chemical reaction at room temperature, which is relatively gentle but the effect may not be long-lasting.

Thermoplastic perm: Using high temperature to accelerate chemical reactions can achieve more lasting and obvious results, but it is more damaging to the hair.

Warm perm: It is between cold perm and hot perm in terms of temperature and chemical strength, aiming to balance the effect and hair damage.

Generally speaking, the effect of perming can last for three to six months, depending on the individual's hair type, growth rate, and hair care method. Some information mentions that under ideal circumstances, current perming technology is actually permanent, and after half a year, the curls will only become larger, but will not return to the original straight hair.

However, there are many factors that affect how long a perm lasts. For example, if a perm is done by a professional at a beauty salon, it will usually last longer than if you use a perm kit at home. To maintain the effect of the perm, keep your hair dry and untouched for the first 48 hours after the perm. In short, the duration of a perm varies from person to person, and good care and professional operation will help prolong the effect.

The effects of a perm can last three to six months (Source: Generated by the author using AI)

Why are the principles of perming and steaming buns similar?

One of the main components of flour is gluten, which is a protein complex composed of two proteins, gliadin and glutenin. Both proteins contain a large amount of cysteine, which can connect to each other through the formation of disulfide bonds, thus providing elasticity and structure to the dough.

During dough kneading, physical forces act on the dough, causing the disulfide bonds in the gluten to break, a process called mechanical reduction. This breakage increases the plasticity and extensibility of the dough, allowing it to be shaped. Then, when the dough is left to rest for a period of time, the disulfide bonds reform, which helps the dough maintain its shape.

Kneading dough causes the disulfide bonds in gluten to break (Source: Author using AI to draw)

During the baking process, heat promotes the formation of more disulfide bonds, which increases the stability and volume of the bread. This is because the formation of disulfide bonds helps stabilize the protein network, allowing the bread to maintain its structure. Therefore, disulfide bonds play a vital role in the dough kneading and baking process. The separation and combination of these disulfide bonds is very similar to the process of perming our hair.

Is perming harmful?

Friends who often perm their hair may worry that the various agents used in perming may endanger our health, and this worry is not unreasonable. For example, in a study published in the International Journal of Cancer in 2020, researchers found that women who used chemical perms more than 6 times a year had about a 30% higher risk of breast cancer. Similarly, according to studies published in Carcinogenesis in 2021 and in the Journal of the National Cancer Institute in 2022, women who use chemical perms more than 4 times a year have doubled their risk of ovarian cancer and doubled their likelihood of developing uterine cancer compared to women who do not use chemical straighteners.

So, can we conclude that perming causes cancer? I'm afraid not, because these studies only show that perming may be associated with an increased risk of certain cancers, but they do not mean that perming will definitely cause cancer . In fact, the occurrence of many cancers has a variety of complex relationships with genetic and environmental factors.

The real conclusion we should draw from these studies is that individuals do not need to suppress their desire for beauty as long as they do not use such products too frequently. However, for professional Tony teachers, it may be necessary to take precautions when helping customers with their hair, because they are exposed to such substances much more frequently than ordinary consumers.

Another problem with long-term perms is that they can deteriorate hair quality. The chemicals in long-term perm products can cause hair to become brittle, damaged, or fall out, especially if these products are used incorrectly. Changes to the hair's protein structure can cause side effects including decreased hair strength, reduced ability to withstand heat styling, decreased hair thickness, and increased roughness of the hair follicles.

Although perming may cause some adverse effects, there are ways to mitigate these effects, such as avoiding over-processing and using moisturizing and repairing hair care products. In addition, current perm products are constantly innovating and improving, and the damage to hair and skin is getting less and less, so as long as you don't perm too frequently, you don't have to worry about your health.

References

[1] Zhang, Yin, et al. "Personal use of permanent hair dyes and cancer risk and mortality in US women: prospective cohort study." bmj 370 (2020).

[2] Bolt, Hermann M., and Klaus Golka. "The debate on carcinogenicity of permanent hair dyes: new insights." Critical reviews in toxicology 37.6 (2007): 521-536.

[3] Turesky, Robert J., et al. "Identification of aminobiphenyl derivatives in commercial hair dyes." Chemical research in toxicology 16.9 (2003): 1162-1173.

[4] Corbett, John F. "An historical review of the use of dye precursors in the formulation of commercial oxidation hair dyes." Dyes and Pigments 41.1-2 (1999): 127-136.

[5] Personal use of hair dyes and risk of cancer: A meta-analysis.

[6] Eberle, Carolyn E., et al. "Hair dye and chemical straightener use and breast cancer risk in a large US population of black and white women." International journal of cancer 147.2 (2020): 383-391.

[7] White, Alexandra J., et al. "Use of hair products in relation to ovarian cancer risk." Carcinogenesis 42.9 (2021): 1189-1195.

[8] Chang, Che-Jung, et al. "Use of straighteners and other hair products and incident uterine cancer." JNCI: Journal of the National Cancer Institute 114.12 (2022): 1636-1645.

Planning and production

Author: Denovo Team

Review | Feng Jun, deputy chief physician of the Dermatology Department of Sinopharm Tongmei General Hospital

Planning丨Ding Zong

Editor: Ding Zong

Proofread by Xu Lai and Lin Lin