Permanent Hair Colour
This is a two step process. When permanent hair dye is applied to the hair, ammonia (alkalizing agent) causes the cuticle to ‘open up’ and let the dye in. Then, peroxide (oxidizing agent) is used to penetrate into the hair cortex and remove your existing hair colour (melanin). Once that happens, the new colour is left in your hair cortex, leaving it a brand new colour or with virgin human hair lokshair! Conditioner is used to close the cuticle back to seal the new colour in. This is also the process used when bleaching or lightening your hair, except the melanin is “eaten away” or extracted until you get the lightened shade that you decide (and your natural hair colour cannot be replaced until it grows back in!).
Semi-permanent Hair Colour
This is a more gentle colouring process which usually lasts 4-6 weeks. Semi-permanent dye doesn’t have ammonia or peroxide, and simply adds tiny colour molecules to the cuticle of your hair without dramatically changing the original hair colour. Since these molecules are small, they eventually escape the cuticle and the colour fades out after several shampoos.
Demi-permanent Hair Colour
This dye lasts a little longer than semi-permanent, about 8-12 weeks, has no ammonia, but a little bit of peroxide. This type of hair colour coats each hair strand with colour and creates larger molecules in the hair cortex, which is why it lasts a little longer.