Your hair consists of strands of the protein keratin. These keratin strands are held together by several types of bonds i.e. disulphide bonds, and hydrogen bonds).
- When heat styling, the hydrogen bonds are temporarily broken down and this effect gets lost when the hair gets wet.
- When chemical straightening, the stronger disulphide are being broken down and reformed (this is permanent).
- When doing a Brazilian keratin treatment, the disulphide bonds are not being broken and therefore are not a permanent treatment.
BKT is based on crosslinking or binding amino acids in the hair fibre. Amino acids are the building blocks of keratin protein.
In order to do so, formaldehyde is used. Formaldehyde is a very small molecule and binds amino acids from the product as well as amino acids in the hair fibre.
The formaldehyde crosslinks the keratin filaments in such a perfect alignment that the hair is now set straight and shines like no other straight hair is capable of but these crosslinks are temporary and wear off in about 3 months.
- The hair is smoother and shinier with these crosslinks. But when they are worn off, the original hair keratin hair structure is damaged.
- The safety concern regarding BKT is due to the use of formaldehyde. When the formaldehyde-containing keratin treatments are applied and heated, formaldehyde gas is released into the air. Exposure to formaldehyde can cause eye irritation and burning of the throat. Salons that use products that contain formaldehyde must follow OSHA formaldehyde requirements and hazard communication standards for worker safety.