"Permanent" hair colouring products consist of two components that are mixed together immediately before application - the "hair colourants" and the "developer" (hydrogen peroxide).
A permant hair colouring product penetrates deeply into the hair shaft and are permanent - they cannot be washed out.
Your hair actually has to grow out over time. Regular touch-ups every four to six weeks are generally needed to eliminate roots (hair with your natural colour growing at half an inch per month from your scalp) and refreshing your colour.
Most permanent hair colours use a two-step process (usually occurring simultaneously) which first removes the original color of the hair and then deposits a new color.
Ammonia opens the cuticle and allows the hair colour to penetrate the cortex. Peroxide is used as an oxidizing agent which removes pre-existing colour. As the natural pigment molecules (melanin) are decolourized, the new dye molecules are bonded to the cortex.
Breastfeeding and hair dyes
Pregnant women and women that are breastfeeding should avoid these kind of chemicals. Some studies have shown that permanent or oxidation dyes can be absorbed through the pores of the scalp and flooded into the bloodstream within minutes of exposure.
In addition to the permanent dyes, the semi-permanent and perm treatments have proven the same effect. Due to the sensitivity involved during pregnancy, it is strongly advised you avoid these chemicals. Once in the bloodstream, they quickly pass through the placenta to your unborn baby.
Luckily some dyes are acceptable. Temporary rinses which only coat the hair shaft (not penetrating the scalp), and natural henna treatments can be used. Whatever you decide, please analise the risks before taking any action you may regret.
- Most styling products contain alcohol which dries out your hair (weaken the hair shaft) and is especially bad for hair that is chemically treated.
- In order to choose the right hair colour you need to make this choice based on a personal analysis of your natural hair colour, eye colour and skin tone. Experts say you also can't miss if you return your hair to its colour when you were a teenager!
- Don't wash your hair for 2 days before you dye it. Your hair will absorb the dye better that way.