Henna can be used as a natural alternative and has many advantages over commercially available synthetic dyes. The henna plant (Lawsonic Inermis) is crushed to make a powder or paste, which contains Lawsone. When henna comes into contact with your hair the Lawsone 'migrates' into the follicle where it binds with your hair's natural keratin. When henna is mixed with a natural plant dye, the colour of the dye is absorbed into this keratin, to create the desired colour. Synthetic dyes, conversely, penetrates the cortex of your hair to alter your natural pigment. In order to penetrate the cortex, the hairs cuticle must be lifted, which is why ammonia and hydrogen peroxide are used. Repeated lifting of the cuticle can lead to the hair become weakened, leaving it dry looking, broken and lustre-less.
Unlike synthetic dyes, henna does not lift the cuticle of the hair to allow colour absorption, nor does it break down the protein structure of your hair. Instead, when the lawsone and keratin combine the hair is strengthened. Henna coats each strand of hair with a translucent layer which enhances and enriches its natural colour ( 'neutral' henna contains no pigment and can be used as a conditioner ).