Semi-Permanent colours are the fastest growing category of colour over the past five years, mainly due to the rise of the funky bold tones we see across Social Media. I am a fan and have always been, my own hair playing testimony to that, with regular changes from violet, to purple, to denim to grey and beyond. It is the nature of a Semi-Permanent colour that allows for predictable colour effects that are easily washed out of the hair opening up multiple changes throughout the year and for some, month to month.
What makes them special is that they are complete dyes; the yellow dye is yellow on the hair; the red dye is red on the hair and so on. Manufactures will use combinations of these dyes to create both pure colours as well as beautiful natural shades.
These complete dyes are known as direct-acting dyes, that can during a development time ‘diffuse’ into the top cuticle layers of the hair from the outside. On the ingredient list they will have great names such as nitro-p-phenylenediamines, nitroaminophenols, nitroanilines, a mouthful to pronounce, pretty impressive when smoothly recited at a posh dinner party.
Making the dyes stick:
The dyes need to stick to the hair otherwise they would brush off or simply fall out. So, each of the dyes contains a charge; some dyes are Cationic (+) having a positive charge, some are Anionic (-) with a negative charge and others are Non-Ionic (0) with no charge. Most of the current formulas available are a mix of Cationic (+), Non-Ionic (0) with a small portion of Anionic (-).
Cationic (+) dyes have a polarising action with the negative charges on the hair making the large direct dyes stick to the outside of the hair, and within the top cuticle layers. Whereas the Non-Ionic (0) which are quite small direct dyes can work their way deeper between the cuticle layers. Both will become dislodged with subsequent shampoos, giving Semi-permanent colours their distinctive non-commitment advantage.
Anionic (-) formulations require a special approach as the hair’s own electrical charge can prevent them from sticking. These formulations are not as common, yes, they are very effective but can difficult to work with and to remove. The formulation changes the charges on the hair to allow the Anionic (-) dyes to move into the cuticles. Once rinsed the hair reverses back to its original charge causing the Anionic (-) dyes to become trapped. Most of these formulas come with a releasing fluid to reverse the electrical changes on the hair’s surface allowing the Anionic (-) dyes to be removed from the hair.
Watch out for staining:
Staining of the hair fibre is a normal part of colouring the hair. Even if all of the dyes could be removed from the hair there will always be a stain left on the hair fibre itself (e.g. like a food stain on clothing or on your nails after removing a strong coloured nail polish). This could potentially influence subsequent applications of colour.
Products you will find containing direct-acting dyes in are:
- Shampoos – for adding, maintaining or correcting tones
- Conditioners – for adding, maintaining or correcting tones
- Semi-Permanent colours (naturally 😉)
- Demi-Permanent colour – for additional shine and vibrancy
- Permanent colours – for additional shine and vibrancy
- Bleaching products that can lift and colour in one step (e.g. Wella Professionals Magma)
Caroline
