Chances are you want to dye your hair or try out different hair coloring techniques. No wonder –  long dyed hair can make your appearance completely different. However, as much as you want to dye your hair, you are also scared at the thought of it. Hair dye and bleaching sound scary, don’t they?

There are huge misconceptions about hair coloring techniques. Many of them point out how damaging such techniques are for your hair. In this article, we will explain what happens when you bleach your hair or dye it, so you can learn about damaging effects. More importantly, you will learn how to avoid them. 

It is important to keep in mind that hair coloring techniques are a matter of science. As you will see, hair coloring is a result of a number of chemical reactions between molecules and pigments in your hair and dye molecules, hydrogen peroxide and ammonia.

Hair coloring basics: Hair structure

In order to understand what happens when you bleach your hair and dye it, we must first understand what the hair structure looks like. To that end, let us first see what each hair strand contains.

Hair is, mostly, keratin. Keratin is the protein, the same one that is found in the skin. Your hair is built from three layers – medulla, cortex, and cuticle.

The medulla is the innermost layer of hair. When it comes to hair dyeing techniques and hair bleaching, chemical treatment in general, this is the least important thing.

The cortex is a layer that encloses the medulla. Most of the melanin is placed in the cortex. Melanin is the pigment that gives your hair color. The natural color of your hair will depend on the ratio and quantities of two melanin pigments – eumelanin and phaeomelanin. Eumelanin is responsible for black and brown shades, and phaeomelanin for red, brown, and ginger hair. If you don’t have melanin in your hair, you must have white or gray hair.

The third layer of the hair structure is the cuticle, the outer layer of hair. The cuticle consists of dead cells. These cells protect the inner layers of the hair – cortex in the first place. When cells lie flat, your hair looks shiny, since light bounces off it. When cells are a bit lifted, you have damaged and brittle hair because the cortex is exposed and prone to damage.

How does hair dye work

During hair coloring techniques, the first thing that happens is the opening of the cuticle. To protect the cortex, many cells lie flat. For this reason, when it comes to dyeing, you have to lift them. Otherwise, chemicals in the dye or bleach can’t get to the cortex. Ammonia the most common alkaline chemical helping bleach and dye get to the cortex. 

What happens when you bleach your hair 

If you want to have bright hair or an intensive and lighter shade than your natural or current color, you should resort to bleach. The bleach reacts with the melanin in the hair. It removes its color during a chemical reaction that cannot be reversed. Melanin molecule oxidizes with bleach. It remains present, but it is colorless.

During the process, hydrogen peroxide is most commonly used for hair lightening. How does hair bleaching work? Hydrogen peroxide enters the cortex, reacts with melanin chemicals responsible for color. This reaction of hydrogen peroxide and melanin results in colorless hair. Sometimes, you can achieve the opposite effect when you want to have darker hair.  The peroxide is used as a solution that opens the hair shaft to allow the peroxide to react with the melanin.

The next step is all about adding dye precursors. This means we add small precursor molecules that will later react and form the final dye. They soak in the cortex through open gaps in the cuticles.

Then, precursors, molecules will react and form the dye. They will react with each other. Hydrogen peroxide and ammonia will help those reactions.  As a result, you have large dye molecules. Because of their size, you cannot wash them out easily.

After this process, it is important to close the cuticle to protect hair dye and your hair’s health. The best way to do this is by applying an acidic conditioner. 

However, there is one crucial thing to keep in mind. This process of opening and closing the cuticle damage your hair. Nonetheless, by choosing the best hair care products, you can reduce the damage caused by chemical treatments. 

Permanent vs demi-permanent hair dye

How long does hair dye last after hair coloring?

When we talk about hair coloring techniques, we must first talk about different types of hair dye. The main difference between permanent, semi-permanent, and demi-permanent hair dye lies in this process of opening and closing of the cuticle. This is where the answer to the question of how long does hair dye lasts lies.

When you are using semi-permanent hair dye – the opening of the hair cuticle is different. In fact, the temporary dye will not open the cuticle. The dye molecules will attach outside of the hair shaft. As a result, you will be able to wash away the color easily.

As its name suggests – demi-permanent hair dye is somewhere between the first two types. It will open the cuticle, but not completely. So, as the final result, some dye will stick on the outside, while some will get inside to the cortex. This means, that it will be harder to wash it off than the temporary hair dye, but easier than the permanent one. Shampooing will eventually dislodge semi-permanent hair color. So, semi-permanent hair colors don’t always require using hydrogen peroxide.

Does hair dye damage hair during hair coloring?

When it comes to whether or not hair dye causes damage or not, you can notice that temporary hair dye causes less damage than permanent hair dye. The less cuticle you open and close, the less damage it creates. But, it is also important to remember there are ways to recover your hair after dyeing. Daily routine and the right hair care products for chemically treated hair are far more important than they may seem.

Natural hair colorants – yay or nay?

It is important to mention natural hair colorants as well. There are plants, minerals, and many other natural agents containing pigment and/or bleaching hair agents. For example, henna contains pigment, vinegar contains bleaching hair agents, etc. You will be able to slightly change your hair color using these hair coloring techniques.

However, you should bear in mind they are not dependable nor will they cause less damage. Also, you cannot get consistent results using these products. Finally, many people are allergic to ingredients that are found in natural products. This means they might not be safer than regular hair dyes. They are also not always less damaging than regular hair dyes, so you should think twice before using natural hair colorants instead of paying a hairdresser a visit.