Difference Between Alkaline and Acid Perm

Hairstyles have been around for as long as humans learned that their hair could be considered as a thing of beauty. A perm is one such hairstyle. ‘Perm’ is short for ‘permanent’. Although, it is not permanent.

As the man developed inventions that could be used in day to day lives, he realised that those products could be used in cosmetics and beauty treatments too. Perming is an example of one such invention.

Perms can be using different methods, i.e. thermal or chemical. The chemical method uses either an acidic or an alkaline base for creating the hairstyle. You can either choose to colour your hair or not.

For creating the hairstyle, the hair is coated with certain chemicals and then wrapped in rods to give them shape. If the chemical contains acid, the hairstyle is called an acid perm. And if the chemical contains a base, it is called an alkaline perm.

Alkaline vs Acid Perm

The difference between an acid perm and an alkaline perm is that the acid perm uses glyceryl monothyioglycylate as an active ingredient while the alkaline perm uses ammonium thioglycolate.

Alkaline vs Acid perm

Comparison Table

Parameters of ComparisonAlkaline PermAcid Perm
Active Ingredient The active ingredient is ammonium thioglycolate. The active ingredient is glyceryl monothyioglycylate.
Alternative Name Also known as cold perms. No alternative name.
Requirement of heat Heat is not required to set the hair. Heat is required for the hair to set.
pH Balance The pH balance for an alkaline perm is between 8.2 to 9.6 The pH balance for an acid perm is between 4.5 and 6.5
Time of setting Alkaline perms only take 20 minutes to set. Acid perms take a longer time to set.
Strength Alkaline perm is stronger. Acid perms are weaker.
Suited for Alkaline perm is more suited for thick and coarse hair. Alkaline perm is more suited for thick and coarse hair.
Effects Alkaline perms can be damaging to hair. Alkaline perms can be damaging to hair.

What is an Alkaline Perm?

Alkaline perms are much more common than acid perms and are also known as cold perms. It has a strong chemical odour like that of ammonia. The chemicals used in alkaline perms are very harsh and can cause hair damage and loss in the long term.

It gives stronger and firmer curls that last for a long time. Alkaline perms can cause changes in the texture of your hair too. This method of perming was introduced first in 1938 as different chemicals started being used in cosmetics and beauty treatments.

Alkaline perming is a harmful method and shouldn’t be done frequently. The perm remains intact for several months and the new roots of hair growing in lessen the effect of curls.

What is an Acid Perm?

An acid perm was the first to be invented. It was introduced in the market around the 1970s. As the chemicals used in acid perms are not very strong and harmful, they take a longer time frame to set. In addition to the application of chemicals, heat is also needed to set the hairstyle.

The results are much softer curls than seen in an alkaline perm. The effect does not last for a long time and can also cause allergic reactions in some people. A bonus point of getting an acid perm is that it is not as harmful to hair as an alkaline perm.

Acid perming is as harmful as alkaline perming but still shouldn’t be done consistently. The perm doesn’t hold for more than a few months and isn’t all that much affected by new hair growing in.

Main Differences Between an Alkaline Perm and an Acid Perm

  1. Alkaline perm uses the base of a salt known as ammonium thioglycolate while acid perm uses glyceryl monothyioglycylate.
  2. Alkaline perms do not require heat to set and are also known as cold perms. Acid perms require heat to set.
  3. While alkaline perms take only 20 minutes to set, acid perms can take much longer.
  4. The pH balance for alkaline perms is between 8.2 to 9.6, while it is between 4.5 to 6.5 for acid perms.
  5. Alkaline perms are much stronger than acid perms and can also cause hair damage.
  6. Acid perms can be used on soft and/or damaged hair, while alkaline perms use harsh chemicals which are more suitable to thick hair.
  7. Alkaline perms can cause hair damage and acid perms may have allergic reactions.


  1. https://www.jstage.jst.go.jp/article/fiber/70/2/70_28/_article/-char/ja/
  2. https://www.sciencedirect.com/science/article/pii/S0190962284701381
  3. https://www.sciencedirect.com/science/article/pii/S019096228370188X
  4. http://www.papersearch.net/google_link/fulltext.asp?file_name=27728739.pdf
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