Unit 1: Matter, Chemical Trends and Chemical Bonding

Altering Chemical Bonds in Hair

In unit 1 we learned about different types of bonds, one of which being hydrogen bonds. Hydrogen bonds as well as disulphide bonds are in the keratin protein in hair.

Hydrogen bonds determine the texture of an individual’s hair; if it is curly or straight. When in contact with water the hydrogen bonds in hair break thus allowing hair to loose some natural texture when wet. Hydrogen bonds are the reason why hair goes back to its natural texture as it dries and the bonds reform.

Within the keratin in the hair’s protein there are naturally occurring disulphide bonds. These bonds form between sulphur molecules in the keratin. Disulphide bonds are responsible for the strength of a person’s hair texture. It is these bonds that are broken in the process of relaxing curly hair to make it permanently straight. In order to break a disulphide bond one of the sulfur atoms in a bond must be removed. By doing so, a more flexible bond called a lanthionine bond is produced. The loss of the sulfur atom weakens the connection between individual hairs which then allows hair to be altered. Chemical relaxers are what alters the hair to make it straight.

On the left is a disulphide bond and on the right is a disulphide bond with a sulfur atom removed, also called a lanthionine bond.




In order to break the strong disulphide bonds and alter hair’s texture the relaxers also need to be very strong. As we learned in unit 2 and again in unit 4 the pH scale can be used to measure how acidic or basic a substance is. The pH scale ranges from 1-14, with 7 being neutral substances. The lower on the pH scale a substance is the more acidic it is, and the higher on the pH scale a substance is the more basic it is. Chemical hair relaxers are more basic ranging usually from a pH of 9-14. Most hair relaxers are solutions of sodium hydroxide (NaOH) or potassium hydroxide (KOH). After the use of the basic relaxer a neutralizer is used to return the hair to a normal pH of about 5. The neutralizer also rebonds the hair into a straight form.

There are concerns regarding the use of strong chemical hair relaxers as they have the ability to burn the scalp. The mistake very often made is that the individual relaxing the hair does not consider the temperature in the room when the relaxer is put on the hair. If the temperature in the room increases the chemical reactions in the hair will occur quicker. This therefore means that often the relaxer is left on too long after the chemical reactions have occurred.

Personal Reflection

I personally am surprised by how seemingly easy it is for someone to alter the bonds in their hair. All you need to do is make a hair appointment or buy an at home relaxer kit. I am also concerned about how easy it is to buy the chemicals. They have the ability to burn the scalp and are easily accessible to possible first time users who have a higher risk of burning themselves.

Question: Do you think at home hair relaxing kits should be sold or should only professionals educated on the chemistry of the chemicals be able to purchase them? Why?


3 thoughts on “Unit 1: Matter, Chemical Trends and Chemical Bonding”

  1. Hi Jenna! First of all, I am pleased to have seen this blog of yours especially that I have tried using hair relaxers in the past despite of my little knowledge about its potential major negative effects. In my opinion, I think that it is definitely best to have a professional perform the hair relaxing. I believe that hair professionals study the chemistry of the medium they use, the effects externally and internally, and other more concerns that makes them reliable. It may be costly to have someone do it, but again, it is safer for our own health. A suggestion I would also make commercially is for the scientists of hair and beauty companies to discover a more basic but effective hair relaxer, especially with the technology that we have in this generation. However, since chemicals are certainly necessary in every product nowadays, another suggestion that I believe would be effective and safe is to have sessions instead of letting the hair ingest all the chemicals all at once, because in that sense, the scalp would have the time to heal, absorb, and internally process the chemicals that have been applied.
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  2. Hey Jenna! Really interesting post, I never knew that hydrogen bonds determine the texture of an individual’s hair. Anyways, to answer your question, I believe that hair relaxing kits should be sold. I do agree with you that individuals will always make the mistake of not considering the temperature in the room when the relaxer is put in the hair, but the individuals buying these hair relaxers will either way damage their hair, professional user or non professional user. There are many toxic chemicals in the relaxers, such as sodium hydroxide, guanidine hydroxide, thioglycolic acid, and lithium hydroxide, which will eventually ruin the hair and deplete the oil the scalp secretes. Some of these chemicals are also used in products like Draino, to dissolve hair in drains and used in depilatories, to dissolve hair. Therefore, hair that has been relaxed will be weaker than if it were natural and will be more prone to problems. Hence why it should be sold to everyone, so they can relax their hair for a short while (even if it ruins their hair in the future). But personally, I think relaxers should not be sold, or should be reformulated to not cause any problems.

    – Cristina Triboi


  3. Hi Jenna, I think that your post was well written and was very informative! It’s interesting how the concepts that we have learned can be applied to our lives, not only for practicality, but also for cosmetic purposes. To answer your question, I do not personally believe that hair relaxes should be sold exclusively at salons simply because of their strength. We interact with many potentially dangerous chemicals in our day to day routines, such as bleach, medications, and cleaners. Generally, people have quite a good understanding of chemical safety and hair kits often come with clear warnings and instructions. Most injuries coming from hair kits are due to the user’s carelessness. Carelessness is not something easily resolved and it can often be applied to other daily hazards such as driving. Thus I do not think that regular people should have a more difficult and expensive time trying to relax their hair. I did enjoy learning about how hair relaxing kits work and to me they seem quite similar to hair bleach. I wonder if they share any similar effects.

    -Cassidy Pacada


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