The Science Behind Perms

I’ve been perming my hair for four and a half years. And, although I typically just read a book while sprawled in the salon chairwiththe smell of ammonia tickling my nose, I’ve always been interested in the science behind perms. Recently, I had a conversation with myself: 

          “Lauren, you’ve taken organic chemistry. Get off the couch and read up on perm-related science.” 

          But my dogs are laying on me.

          “You’re a pain in your own ass. Get up.”

The truth set me free, and here we are now, ready to dive into a perm-y, science-y wormhole. (For those who are interested in exploring the science behind perms in more depth, check out my citations!). 

Hair is mostly composed of a protein called keratin. Many keratin molecules amass to form the macrostructure of a single strand of hair. Two keratin molecules can “connect” through a disulfide bond (this is possible based on keratin’s macromolecular structure); the more disulfide bonds between keratin molecules, the straighter the hair. This type of connection is a permanent one except in the face of certain forces and/or chemicals. 

A standard perm follows a simple procedure: First, the hair is washed and wrapped around rods (which are similar to curlers). Then, a solution is applied to the hair and allowed to sit for a few minutes. Following the “incubation process,” the hair is rinsed (the rods are still in at this point). Then, a second solution is applied to the hair and allowed to incubate. Finally, the hair is rinsed as the rods are removed. 

The first solution applied during a standard perm is a reducing agent, ammonium thioglycolate. I won’t go into details on the process of reduction here, but suffice it to say that this chemical can break the disulfide bonds between keratin molecules. This allows the hair to take the shape of whatever it is in contact with (i.e., the rods). 

The first solution is mostly rinsed out to prevent hair lightening with the application of the second solution. The second solution is called a “neutralizer” and is typically hydrogen peroxide. Hydrogen peroxide is an oxidizing agent and, thus, has the capacity to reform disulfide bonds between keratin molecules. Once the disulfide bonds have been re-formed, the rods can be removed. At this point, the hair takes the shape of the rod and is, thus, curly.  

The chemicals required throughout the perming process weaken the hair, so it’s important to wait a certain amount of time between subsequent perms; typically, perms should hold up for six months or longer.  

If you have specific questions regarding your perm or whether your hair can handle a perm, consider browsing the Internet AND consulting with a stylist. Maybe 2019 will be the year of The Curl!




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