Hair is mainly keratin, the same protein found in skin and fingernails. When warm and wet it’s soft and pliable. When dry or heated it hardens and protects the hair’s inner structure.
The natural color of hair depends on the ratio and quantities of two other proteins, eumelanin and phaeomelanin. Eumelanin is responsible for brown to black hair shades while phaeomelanin is responsible for golden blond, ginger, and red colors. The absence of either type of melanin produces white or grey hair pigment deficient. It is having an understanding of these pigments that is key to successful hair colouring .Do we want to utilise or neutralise the pigment’s as we expose them in the lifting process.This in simple terms is do we want to sue the pigment to enrich the colour and shade or do we want to control or mask it!
As I stated at the start of this topic man and different cultures have been coloring their hair for thousands of years. Using plants extracts and minerals. It is these pigments found in such products as (e.g., henna, black walnut shells beetroot juice.) others contain natural bleaching agents or cause reactions that change the color of hair (e.g., vinegar lemon juice). Natural pigments generally work by coating the hair shaft with colour they coat the outer shaft some times lasting for several shampoos, however they aren’t necessarily safer or more gentle than modern formulations. So can have metallic salts in them. Some can and will build up on the hair.In some cases they cannot be removed. It’s difficult to get consistent results using natural colorants, Skin test is alway recommended even with these so called natural products
Temporary Hair Color
Temporary or semi-permanent haircolors may deposit acidic dyes or direct dyes onto the outside of the hair shaft .Direct dyes are fully matured and so are to big to be readily absorbed into the inner hair structure.unless an amount of an alkaline is present to open the cuticle. In some cases smaller pigment molecules are used they can more readerly slip inside the hair shaft some using a small amount of peroxide.
If peroxide is used in a product one should expect some lifting of the hair natural level and possible warmth from said lifting of the pigment. or none at all depending on formulation. In some cases, a collection of several colorant molecules enter the hair to form a larger complex inside the hair shaft. Shampooing will eventually dislodge temporary hair color. These products don’t contain ammonia, but may have some other form of alkaline in them. If an alkaline is present the deposit will be more long lasting that normal temporary colour.
In normal temporary colour the hair shaft isn’t opened up during processing and the hair’s natural color is retained once the product washes out.
How Lightening Works
Bleach is used to lighten hair. The bleach reacts with the melanin in hair, removing the color in an irreversible chemical reaction. Normally after bleaching toning will be required to some degree to neutralise unwanted undertone exposed. The bleach oxidizes the natural melanin molecule. The melanin is still present, but the oxidized molecule is colourless. Bleached hair that is fully lifted of pigment will retain a pale yellow hue. The yellow colour is the natural colour of keratin, the structural protein in hair.
Bear in mind bleach reacts more readily with the dark eumelanin pigment than with the phaeomelanin. Some gold or red residual colour may remain after lightening,again tis is when toning may be required to rebalance the pigment exposed.
Hydrogen peroxide is one of the most common lightening agents. The peroxide is used in an alkaline solution, which opens the hair shaft to allow the peroxide to react with the melanin lifting it in degree’s depending on the strength of peroxide timing and formulation.Of course it will also vary depending on the natural level of the hair .the darker the hair the more lift will be required and so the longer it will take to get a desired level of lift.The darker the shade the more red and orange you will have to contend with when trying to get to that pale yellow. required if you want a very blonde tone!
Permanent Hair Color
The outer layer of the hair shaft is the cuticle or order to permanently change the hair colour and for new artificial colour to be deposited into the hair we have to open this cuticle. We open the cuticle by using an alkaline and raising the hair’s natural Ph from around 5.5 up to around 7 in some cases higher levels are used this can and will damage the hair and lead to poor colour retention. The dye reacts with the inner portion of the hair, the cortex, to deposit or remove the color. Most permanent hair colours use a two-step process normally they work simultaneously. First removes the original colour of the hair at the same time depositing the new color. It’s essentially the same process as lightening, except a colorant is then bonded within the hair shaft.
Ammonia or another alkaline is the chemical that opens the cuticle and allows the hair color to penetrate the cortex of the hair. It also acts as a catalyst when the permanent hair color comes together with the peroxide. Peroxide is used as the developer or oxidizing agent it does this by aggravating the colour molecule and making it swell. The developer removes pre-existing color. Peroxide breaks chemical bonds in hair, releasing sulfur, which accounts for the characteristic odor of haircolor. As the melanin is decolorized, a new permanent color is bonded to the hair cortex. Various types of alcohols and conditioners may also be present in hair colour. The conditioners help close the cuticle after colouring and re balance that Ph level to seal in and protect the new colour.Alcohol is quite drying on the hair and is also another ingredient used to open the cuticle in the colour process,It can be also found in semi and temporary colours again to help with deposit of the colour molecules.
In closing this rather long and technical blog all is not what it always seems and appears to be. Understand that chemistry trust your knowledge and research stay informed question and think. As and raise question seek the answers you need. Remember This! The only stupid question is the one never asked!