Perm (hairstyle) - Modern Perms

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 neutralizer is applied to bring down the pH and rebond the hair.

Other types of modern perms include exothermic perms, which are self timing and self heating; and neutral, or low pH, thioglycolate free perms.

The permanent relaxer straightens the hair instead of curling it. The same chemical methods can be used for this, but the hair is not wrapped around rods. This process is commonly used by those of African ancestry and others with naturally curly or kinky hair.

Digital perms were introduced in the 21st century and in use especially in modern Asian cultures. The process was patented and invented by a Japanese company, Paimore Ltd.