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How Do Perms Work – Breaking Down the Secret

The common perm (originally known as the "permanent") allows for a wide variety of hairstyles and designs.

Fundamentally, the perm re-structures the molecules of the follicles - re-aligning and resetting to enable straightening, curls and waves.

The process typically will last a month or so depending on frequency of washes and shampoos and can be enhanced by styling aids and keratin shampoos that help maintain hold.

Most people have accepted that the way their hair looks depends greatly on genetics and it is your genes that determine whether yours is straight, curly or somewhere in between.

While most methods such as curling irons will only last until the next time the hair is washed, perms were developed to last for a much longer period of time by working into the individual strands and temporarily changing their structure.

How Long It Lasts

One important thing to know about perms is that because they alter the structure of the shaft, they do not wash out over time. Instead, they will slowly fade out as the new strands are created and grow and this process usually takes around six months.

Perms are a popular method of curling not only because they last for such a long period of time, but also because they only take one or two hours to apply. Keratin treatments are also useful in-between perms, straightening or coloring services. Keratin treatments help strength and hold styles in place and extend the life of permanents.

Understanding Hair Structure

In order to fully understand how perms work, you must first understand the structure of each individual hair strand because it is this structure that is affected by the perming process. In each piece of hair, around 95% of its structure is made up of keratin, a protein with a long and helical shape.

These individual keratin protein molecules congregate and form photofibrils which are larger helices. These photofibrils then form macrofibrils and microfibrils which compose the superstructure of your individual strands.
Keratin molecules contain cysteine, an amino acid containing reactive sulfur atoms. When two cysteine residues that are on different keratin molecules connect, they create a disulfide bond which is an incredibly strong connection binding the two molecules together. This disulfide bond is permanent unless a strong external force acts upon it.

How Perms Work

Perms rely on these disulfide bonds to produce their results. It helps that the disulfide bond is weaker than bonds within an individual keratin molecule which means that a force strong enough to break the bond will not destroy a keratin molecule.

In most perms, a chemical such as the reducing agent known as ammonium thioglycolate is placed in the hair and this causes the disulfide bonds to break. When this occurs, the keratin molecules will adjust to the shape of the shaft which is placed in curlers. After that, a neutralizer (commonly hydrogen peroxide) is put on and this allows the formation of new disulfide bonds, effectively locking the curls into place.

While we mention curls, in particular, perms used as a technique for straightening hair, building wide waves, and for locking in place complex styles...but, as is most common, the process is most commonly used for getting "perfect curls".

The Process

Despite the complicated chemical and structural processes taking place during a perm, the physical process is fairly simple and doesn’t usually take more than an hour or two. In the standard procedure for a perm, the hair is first placed into curlers.

After this, the reducing agent is placed on, where it sets for a certain amount of time. Then the neutralizer is added. It is important not to wash the hair for several days after getting the perm as this can counter the chemical and structural changes that took place.