Coloring, hair lightening - hair protection solutions

Colouring, bleaching hair - hair protection solutions

The first industrial-scale hair colouring product was created in 1909 by French chemist Eugene Schuller. Today, hair colouring has become a very popular treatment, with greying considered the main cause. It is estimated that more than 75% women already dye their hair and the percentage of men undergoing this activity is also growing. The colour of our hair is a matter of chemistry. With the right protection during colouring, it is possible to achieve beautiful, healthy hair colour.

Natural hair colour

The colour of our hair is determined by the amount of melanin it contains. Melanin is a natural pigment produced by the melanocytes contained in the skin. There are three types of melanin:

• eumelanin - gives colour to dark, brown and black hair,
• Pheomelanin - responsible for the light shades of hair,
• tricosideria - responsible for red hair colour.

Melanin has a protective function and prevents skin ageing (neutralises free radicals). It accounts for approximately 3% of hair mass and is most abundant just under the hair cuticle. Hair colour depends on the combination and amount of melanin components. The least melanin is contained in blonde hair and the most in black hair. When the melanin process in hair stops, hair turns grey.

Hair colouring and bleaching - definition

Colouring, or hair dyeing, is the alteration of a natural or previously altered colour by means of special chemicals. In order for colouring to take place, the hair cuticle must be opened and the dye is then able to react with the inner part of the hair, depositing or removing the dye there. Hair dye is only able to change the colour by a few shades, so the transition from dark to light hair is already a completely different method called bleaching.

Hair colouring products

The classification of hair colouring products is based on the depth of penetration of the dyes into the different parts of the hair shaft. In terms of permanence, there are 3 types of colouring:

• permanent colouring - giving a long-lasting effect once the dye has reached the hair cortex,
• semi-permanent colouring - up to 24 washes of hair, when the dye remains on the hair surface,
• temporary colouring - washable hair colouring (2 to 4 washes) that uses high molecular weight dyes with water-soluble properties.

Permanent dyes are oxidative products that rely on two key ingredients: an alkalising agent, which contains the dyes, and an oxidising agent, which induces the colour. Permanent dyes cannot be washed off and are a more traditional way of permanently changing hair colour. They produce an effect that is resistant to washing and are selected to provide a long-lasting colour change, from subtle to intensive, as well as excellent coverage of 'grey' hair. Permanent colouring preparations usually contain ingredients such as para-aminophenol, para-phenylenediamine, para-toluenediamine or hydrogen peroxide.

The semi-permanent dyeing treatment uses nitro, azo and anthraquinone dyes.

In contrast, a short-term colouring treatment is carried out using aniline dyes, which adsorb to the surface of the hair.

Hair bleaching agents

Hair lightening preparations include alkalising substances, lightening enhancers, carrier substances, thickening substances, wetting substances and colouring agents. The former include ammonia water, sodium phosphate and potassium. Their function is to open up the hair cuticle and disperse the hair pigments. Strengthening agents are mainly sodium persulphate or magnesium peroxide. When mixed with an oxidant, they react with water and release additional amounts of oxygen, which oxidises melanins; they are only added to professional preparations for strong bleaching. The lightening of the hair is determined by the amount of oxygen released during the treatment. The carrier substances, or emulsifiers, are designed to bind the oxidising agents, preventing them from dusting, so that the brightener does not run off the hair. An important group are the colouring agents, which are added to the brighteners to avoid yellowing of the hair. In order for the brightener to work, an oxidant, i.e. activating hydrogen peroxide, is needed. With one application of the product, it is possible to lighten hair by 3 to 7 tones.

Mechanism of oxidative dyeing

The permanent colouring process uses colourless oxidative dyes, which react with each other under the influence of an oxidant to form high-molecular-weight colour compounds. The entire process is divided into two stages. The first involves the decomposition of the alkalising substances with the release of OH^-which then dissolves the lipid mantle, breaks down the hair scales (pH approx. 8) and neutralises the decomposition stabiliser hydrogen peroxide. The dye components - aromatic diamines - penetrate the hair cortex. Their oxidation takes place. In the second stage, the oxidation products of the diamines conjugate with other low-molecular components (e.g. resorcinol), resulting in the formation of high-molecular colour bonds, which are locked into the hair structure. Using the combination of the corresponding phenylenediamines and the components conjugated to them, it is possible to obtain a wide range of colours for coloured hair.

Mechanism of hair bleaching

The hair bleaching procedure is based on the reaction of the hair bleaching agent with the melanin in the hair resulting in its breakdown. The melanin is destroyed by oxidising substances, so-called oxidants. The concentration of oxidants used in hair salons fluctuates between 1.5% (the weakest) and 12% (the strongest). The entire process takes place in an alkaline environment (pH 9-10), allowing the hair to swell, the hair scales to open and the oxidising agent to penetrate the cortex with melanins. The process takes place in two stages. Initially, pigments (eumelanins and pheomelanins) are released and dispersed from the pigment grains, and then the oxidant acts on these pigments and lightens them. At the end of the treatment, a shampoo and conditioner is applied to the hair to restore the optimum pH and close the hair scales. During the bleaching process, the hair goes through different shades - from red to orange to yellow. This is because eumelanin decolours very quickly, while pheomelanin decolours slowly and a certain amount remains in the hair.

Safety of hair dyes

Hair dyes and other hair colouring preparations are classified as cosmetic products and their ingredients are subject to specific regulations under Regulation (EC) No 1223/2009 of the European Parliament and of the Council. Before such a cosmetic is placed on the market, it must undergo a rigorous safety assessment by a qualified professional called a safety assessor. The safety assessment involves a thorough analysis of the finished product, all its ingredients, as well as the manner and frequency of use. Pigments used in colouring preparations are a very well-studied group of substances. There are extensive scientific studies and opinions on them issued by the independent expert panel CIR (Cosmetic Ingredient Review), the Scientific Committee on Consumer Safety (SCCS), which operates at the European Commission or the US Food and Drag Administration (FDA). However, allergic reactions to some hair dye ingredients sometimes occur. A small number of people may have an allergic reaction to the hair dye used, for example, the scalp may become itchy or red after hair dyeing. A person who is allergic to a substance is likely to be allergic to it for the rest of his or her life and must avoid exposure, even if the ingredient is found in a different type of product or brand. To avoid potential allergic reactions, follow the instructions on the label of such a product. Applying an allergy test as recommended by the manufacturer helps detect any slightest reaction on a small area of the body before applying the product to the whole head.

Hair colouring techniques

Nowadays, hair colouring is all about playing with colours to achieve amazing effects - from natural highlights to bold, intense colours. The colouring trend is particularly noted in the fashion world and several types of colouring have been developed based on this trend:

• ombre - involves gradually lightening the ends of the hair while leaving a darker shade at the roots,
• sombre - is a softer version of ombre, where the hair is left in its natural shade at the roots, while the ends are lightened by 2-3 tones,
• balayage - is the lightening of selected areas of the hair to give a voluminous, fresh and shiny effect,
• flambayage - is a softer version of the classic baleyage. It allows for a much more natural summer 'tan' effect on the hair,
• Diamond colouring - involves the use of Elumen paint, which uses the magnetic attraction of the pigments to produce saturated, brilliant colours,
• Global colouring - is a two-step treatment involving decolourisation followed by target colouring (ombre, sombre, highlights, etc.),
• ronze - involves a combination of brown at the roots and red at the ends,
• bronze - a combination of brown at the roots and blonde at the ends, the colouring can be very subtle with a subtle transition between "top and bottom" or more pronounced and contrasting,
• splashlight - involves lightening and brightening the middle more often, where the hair at the roots and ends remains the same dark shade,
• air touch - literally translated means 'touch of air'. In practice, the strands are slightly lightened and have several shades that blend seamlessly,
• hand touch - so called "free hand" colouring. The stylist individually adjusts the distribution and amount of blonde highlights according to the client's wishes. The resulting colour is multidimensional and the final effect is very natural,
• Hair toning - a treatment that darkens the hair,
• Holographic hair colouring - involves creating a rainbow effect by mixing different shades from blonde to brown to candy pink, blue and purple.

Care for coloured and bleached hair

Colouring and bleaching hair has quite an invasive effect on the hair fibre. The agents that lift the hair cuticle disorganise its natural structure, which can make hair weaker, more susceptible to mechanical damage, dryness and more brittle. In addition, bleaching products wash away the cement that glues and seals hair scales together. The alkaline pH promotes the disruption of keratin chains in the cortex by destroying the disulphide bonds that connect them and the amino acids that build these chains. As a result of the above-described reactions, the strength of the hair is reduced and its porosity and roughness are increased. The hair can be properly prepared before colouring and can be cared for after the treatment.

Protection of the scalp

It is very important to properly protect the scalp before colouring with dedicated preparations called blockers. These minimise the negative effects of the chemicals by eliminating the dryness and burning sensation after application. In this way, the scalp will not be irritated after colouring and the hair follicles will not be damaged. They are designed to maintain the biofilm and pH at the right level, necessary for proper keratinocyte proliferation. The ingredients in such preparations are usually amino acids, proteins, natural extracts and oils.

Protection during colouring 

Hair colouring is a rather aggressive chemical treatment that is supposed to open up the hair and lock the pigment there with the new colour. Hair salons are increasingly using new ways to limit the damage to the hair during colouring. There are several very intensive regenerations available on the market among which olaplex, fibreplex, nanoplex, smartbond or TCA drops are leading the way. Each of these products, when added to paint or bleaching powder, protects the hair cuticle.

OLAPLEX

It is a product with concentrated repair action, which owes its effectiveness to the presence of an ingredient called bis-aminopropyl-diglycolic imaleate. Its role is based on the restoration of disulphide bridges damaged during treatment. Hair after colouring with it becomes full of shine, strengthened and smooth. Frizz is reduced and hair is more manageable. The fibreplex and nanoplex systems work on a similar principle.

SMARTBOND

This is a professional colouring additive that contains maleic acid in its composition. Its action is based on the weakening of the ionic-hydrogen fibres, by maintaining the cohesion of the disulphide bridges in the hair structure. In addition, other valuable ingredients include polymers and ceramides, which add softness to the hair and make it more amenable to modelling.

TCA drops

This is nothing more than a colouring oil used during a hair colouring or bleaching treatment. Its origins date back to the 1980s and it can reduce the colouring time by up to 70%. Its action is based on three active ingredients: mineral oil, jojoba oil and vitamin E. The Color Accelerator (TCA) slows down the breakdown of hydrogen peroxide in the hair and stabilises it. The antioxidants in the product support the colour molecules during colouring. As a result, hair is silky smooth and nourished after the colouring treatment. The product also protects the scalp from the chemical components of the dyes. There are similar formulations on the market based on other oils such as avocado oil, grape seed oil, sweet almond oil, etc.

Hair protection after colouring and bleaching treatment

It is also worth taking care of coloured hair at home. There are many preparations available on the market for this purpose. Products for bleached hair should contain nourishing ingredients such as vitamins, plant extracts, including chamomile, ceramides, panthenol and elastin. It is best to look for water-retaining ingredients (keratin, silk, plant proteins), humectants (honey, glycerine, aloe vera) and emollients (silicones and oils) in hair care products for colour-treated hair. These provide shine and softness to the hair to the touch and protect the colour from fading and UV damage.

Summary

Colouring is a very popular and one of the most frequently chosen beauty treatments. It allows a quick change of appearance and covers grey hair. Various colouring and bleaching techniques are used in hair salons to guarantee the beautiful hair colour of your dreams. However, this is a procedure that interferes quite a lot with the hair structure. With the use of professional preparations, it is possible to effectively protect the hair and scalp during this procedure. The cosmetics industry is constantly striving to develop new, innovative technologies that increase the safety of hair dye preparations and protect hair fibres from damage.

Author:

Monika Rek

MA in chemistry, co-founder and Safety Assessor at MPR Labs. She has several years of experience in the beauty industry, in the field of safety assessment of cosmetic products. She assists in the implementation of cosmetics in the European market.

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