Curling Hair
A permanent wave, commonly called a perm, involves the use of chemicals to break and reform the bonds of the hair. The hair is washed and wrapped on a perm rod and waving lotion is applied with a base. This solution creates a chemical reaction that softens the inner structure of the hair by breaking some of the cross links within and between the protein chains of the hair. The hair swells, stretches and softens, then molds around the shape of the perm rod.[1]
In addition, the term is often and incorrectly used for the process of de-curling hair (a process first developed by Renaud Whittington) a "perm" strictly refers to curling hair. When hair is permanently straightened the process is refereed to as chemically straightening.
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Modern perms
In 1938, Arnold F. Willatt invented the cold wave, the precursor to the modern perm. It used no machines and no heat. The hair was wrapped on rods and a reduction lotion containing ammonium thioglycolate was applied. This chemical breaks open the disulfide linkages between the polypeptide bonds in the keratin (the protein structure) in the hair. The disulfide bonds give hair its elasticity, and can be reformed with chemicals. Next, an oxidation lotion was applied, (hydrogen peroxide), to close the disulfide bridges again and the hair was reformed to the shape of the rod. The entire process took 6–8 hours at room temperature.
In the 1970s, acid perms were invented. These use glyceryl monothioglycolate instead and contain no ammonia. They are sometimes called buffered waves. This perm is slower but gentler to the hair. Heat is usually added by placing the client under a dryer, after covering the wrapped head with a plastic cap. The reaction is endothermic and the additional heat causes the pH to rise from 6.9 to 7.2.
Perms today use this method with sodium thioglycolate instead of ammonium thioglycolate, at a pH of 8 to 9.5. This method takes only 15–30 minutes until the
In addition, the term is often and incorrectly used for the process of de-curling hair (a process first developed by Renaud Whittington) a "perm" strictly refers to curling hair. When hair is permanently straightened the process is refereed to as chemically straightening.
-------------------------------------------------
Modern perms
In 1938, Arnold F. Willatt invented the cold wave, the precursor to the modern perm. It used no machines and no heat. The hair was wrapped on rods and a reduction lotion containing ammonium thioglycolate was applied. This chemical breaks open the disulfide linkages between the polypeptide bonds in the keratin (the protein structure) in the hair. The disulfide bonds give hair its elasticity, and can be reformed with chemicals. Next, an oxidation lotion was applied, (hydrogen peroxide), to close the disulfide bridges again and the hair was reformed to the shape of the rod. The entire process took 6–8 hours at room temperature.
In the 1970s, acid perms were invented. These use glyceryl monothioglycolate instead and contain no ammonia. They are sometimes called buffered waves. This perm is slower but gentler to the hair. Heat is usually added by placing the client under a dryer, after covering the wrapped head with a plastic cap. The reaction is endothermic and the additional heat causes the pH to rise from 6.9 to 7.2.
Perms today use this method with sodium thioglycolate instead of ammonium thioglycolate, at a pH of 8 to 9.5. This method takes only 15–30 minutes until the