How Does Bleach Lighten Your Hair?


Bleaching powder, or hair lightener, is a popular product for lightening hair colour. Many use bleach powder to achieve a blonde or lighter hair colour, or to add or remove any permanent hair dye.

However, have you ever wondered how bleach powder changes your hair colour? In this article, we will explore the science behind the process.

Bleach Powder

Bleach powder is a chemical mixture of persulfates and other compounds designed to lighten hair through opening up hair follicles by raising the cuticle (outer layer of the hair strand) and breaking down the natural melanin pigments inside that give hair its colour.

When a bleach powder and hydrogen peroxide mixture is applied to the hair, the hydrogen peroxide and persulfates work together to break down the melanin pigments. As the pigments are broken down by oxidation, the hair becomes lighter and can take on a blonde or lightened colour.

Hydrogen Peroxide

Bleach powder is activated by mixing it with a product called hydrogen peroxide (H2O2), which is a powerful oxidising agent. Once activated, the mixture releases oxygen molecules that break down the melanin pigments in the hair. The persulfates, a type of salt, work as catalysts to speed up the oxidation process as well as open the hair follicle to expose the natural pigments in the hair to the oxidative mixture. The amount and strength of hydrogen peroxide determines how fast and, therefore, how much your hair colour will change according to how long the mixture is applied.

Hydrogen peroxide is usually supplied in a dilution cream, also known as developer cream, cremoxy or crème peroxide (In the case of crème vs cream, they are used interchangeably, with crème being the french name for the English cream) or CROX for short. Cream-type emulsions enable finer control and ease of application.

Diluted hydrogen peroxides are also available in liquids, colloquially called Liquid-oxy or LOX for short. These are more common at higher concentrations of hydrogen peroxide due to the stability issues caused by oxidative effects.

The strength of this cream, usually called a developer, is denoted by its “VOL”. The higher the VOL, the higher the concentration of H2O2 and the faster it will react with your hair. Higher VOLs should be on your hair for shorter durations to prevent unnecessary damage to your hair follicles.

Below is the breakdown of concentrations of hydrogen peroxide per VOL:

5 VOL = 1.5% hydrogen peroxide

10 VOL = 3% hydrogen peroxide

20 VOL = 6% hydrogen peroxide

30 VOL = 9% hydrogen peroxide

40 VOL = 12% hydrogen peroxide

50 VOL = 15% hydrogen peroxide

60 VOL = 18% hydrogen peroxide

Hair Structure

To understand how bleach powder works, it’s important to know the structure of your hair. Each hair strand comprises several layers, including the cuticle, cortex, and medulla. The cuticle is the outermost layer of your hair and protects the inner layers.

The cortex is the middle layer and contains the natural pigments that give your hair colour. When you bleach your hair, the persulphates in the bleach powder raise/open the cuticle layer, allowing hydrogen peroxide to penetrate the cuticle and cortex layers, reaching the natural pigments in the cortex. The hydrogen peroxide then oxidises the pigments, causing them to break down and become colourless.

As the pigments in your hair are broken down, your hair colour lightens. If you have dark hair, you would need a stronger bleach and peroxide mixture, it may take several rounds of bleaching to achieve a significant colour change. On the other hand, if you have light hair, the bleach will work quickly to remove any remaining pigments and lighten your hair even further.

Take Care When You Bleach

Hydrogen peroxide affects the pigments in your hair and the protein structure of your hair. Your hair comprises a protein called keratin, which provides strength and structure. When hydrogen peroxide comes into contact with your hair, it breaks down the keratin molecules, weakening the protein structure of your hair.

The damage caused by bleaching can manifest in various ways, including:

  • Dryness: Bleaching can strip your hair of natural oils, leaving it dry and brittle. Dry hair is prone to breakage, leading to split ends and other types of damage.
  • Breakage: The more you bleach your hair, the more damage it can cause, leading to breakage and hair loss.
  • Porosity: Bleaching can increase the porosity of your hair, making it more porous and prone to damage from heat, chemicals, and other environmental factors. Porous hair can also absorb too much moisture, leading to frizz and other types of damage.
  • Colour Fading: Bleaching can cause your hair colour to fade. This is because the hydrogen peroxide in bleach powder can break down the artificial pigments used to colour your hair, causing the colour to become less vibrant.
  • To minimise the damage caused by bleaching, it’s essential to use it properly and follow these tips:
  • Avoid over-bleaching your hair: The more you bleach your hair, the more damage it can cause. It’s essential to space out your bleaching sessions and avoid over-bleaching your hair.
  • Use a lower concentration of hydrogen peroxide: When using bleach powder, it’s essential to use the lowest possible concentration to achieve the desired results so that you minimise the damage caused to your hair.
  • Deep condition your hair regularly: Deep conditioning treatments can help to restore moisture in your hair and prevent it from becoming dry and brittle.
  • Avoid using heat styling tools: Heat styling tools can further damage your hair and make it more prone to breakage. It’s best to avoid using heat styling tools and allow your hair to air dry whenever possible.

Going Blonde

Bleaching changes your hair colour by oxidising the natural pigments in your hair with hydrogen peroxide. The strength and amount of hydrogen peroxide used determines how much your hair colour will lighten.

It’s important to use bleach powder carefully to avoid damaging your hair. With proper care and maintenance, bleaching your hair can be a great way to achieve a new look and transform your appearance.

AIC Bleach Powder

AIC’s bleach powder is dust-free and develops excellently. Our range comes in various colours and with active ingredients that conditions hair during bleaching. The coloured bleaches allow for toning of the hair colour to mask natural yellows or bring out natural reds, etc.

We’ve made our bleach products more stable in recent years by improving our manufacturing process. The best part is that we’ve also been able to reduced our pricing on these products over time despite increasing raw material prices.

AIC’s bleach range can be divided into two categories:

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