To follow up on my previous post about colour fade, i will explain to you why permanent colour should never be applied to the mid lengths and ends of your hair.
So, we all know that colour fades and that we can take steps to pro-long it, but we can never stop it.
Virgin hair needs a more alkaline colour to be able to accept colour. Aged hair (lengths and ends) are usually more sesetised and accept colour differently than virgrin hair.
The main difference between permanent and semi-permanent or tone on tone hair dye, is the size and behaviour of the colour molecules.
Permanent hair dye-contains large and small colour molecules. The large mollecule will stain the hair cuticles and do not enter the cortex.
The smaller mollecules however do enter the cortex.
The higher volume of peroxide and the presence of ammonia forces the hair cuticle open to allow the colour molecule to penetrate the hair where upon entering the cortex, the mollecule then oxidises and enlargens so that it becomes too big to slip back out. -Thus making the dye more permanent.
This information explains why we can use shampoo like Vosene to help strip some dye from hair but it never washes all of the dye out-Shampoo like Vosene will only remove the dye that is sat on the cuticles-not the dye in the cortex.
To remove dye from the cortex it must either be lifted out or the oxidisation process must be reversed to allow the molecules to then be rinsed out.
Permanent hair colour taken through the mid lengths and ends of hair will eventually lead to colour build up and damage.
The lengths and ends of hair is always more porous than the roots. Porous hair takes colour differently than virgin hair (root area).
One colour will not do all!
Semi-permanent or tone on tone-Contains only large colour mollecules. These sit on the outer layer of the hair (the cuticle) and do not oxidise inside the cortex. As this type of colour only sits on the outside, it gradually fades out.
Many tone on tone colours are low ammonia and use a very mild peroxide (1.6% or 10vol) as appose to a permanent colour (6% to 12% or 20vol to 40 vol) with some now also being completely ammonia free.
Many TOT colours also contain conditioning properties too. This helps to restore condition and shine to the hair when used.
The low peroxide used means that there is less risk of damage or colour build up.
So, why do we not use permanent colour on zones 2 & 3 of your hair?
We use semi-permamenet gloss because it is more conditioning to aged hair.
Aged hair absorbs colour differently to virgin hair.
It provides a high shine finish.
It gradually fades so you will not get colour build up
It is easier to remove or lift out should you fancy a colour change
Easy to change your tones with the seasons
Gloss or tone on tone will not damage your hair at all.