Hair dyes: tips on which to choose and how to use them

Recent market research has shown that today around 80% of all women regularly use hair dyes and - albeit to a lesser extent - even a considerable percentage of men are starting to display a strong interest in this product.

There are various reasons that lead someone to dye their hair using at-home hair dyes or at their hairdressers: wanting to cover grey hair, a personal desire to change their look or to follow the fashion trends of the moment.

Natural hair colour is determined by the size and number of melanin granules that are concentrated in the hair shaft cortex.
For black or brown hair, there are many of these big granules, while they are smaller and sparser for light hair. Without melanin, hair becomes grey or white. This loss of colour is called canities or achromotrichia.

Grey hair is more evident in people who have darker hair, however hair usually goes completely grey earlier for people with blond hair. Usually hair starts to turn grey between the ages of 30 and 40, both for men and women. If it happens before the age of 20, then this is considered premature greying of the hair.

Hair dying is a custom that has very ancient origins, as attested to by the discovery of henna leaves in Egyptian tombs. However, exclusively plant-based dyes are not very common as they are generally less practical and cannot compete in terms of the range of colours that can be achieved.

Today the market offers an extremely wide range of products for dying hair which are classified according to how long the dye lasts. As such, there are temporary, permanent and semi-permanent dyes.

Let’s look at the main types of hair dyes in more detail:

• TEMPORARY DYES: either in lotion, spray, mousse or shampoo format, they give a light surface colour and can be removed very easily by washing your hair. Some examples of this kind of dye include coloured dyes to cover grey hair, which are formulated as hairsprays that also contain pigments.
• SEMI-PERMANENT DYES: these are based on direct dyes and are effective in changing your base colour as they permeate the hair. This is a ready-to-use product and the colour washes out after the 4th or 5th wash. Shampoo or conditioner colour and shine glosses are one example of semi-permanent dyes.
• PERMANENT DYES: these are called “permanent” because the colour cannot be “removed” from the hair. At most it will fade over time with washing and sun exposure. They last for around a month, when regrowth becomes a problem, which is more visible the greater the difference between the colour of the hair dye and your natural colour. In technical jargon, these are known as oxidation dyes as the colour develops directly within the hair shaft, thanks to the oxidant, hydrogen peroxide. In fact, mixing is required before application and these dyes can give hair an endless colour palette to choose from and completely cover greys.

If you have decided to purchase a DIY hair dye, i.e. an at-home product, you should be aware of various things.

One of the main things to evaluate is your choice of colour which should take into consideration your natural hair colour.

Hair colours are identified by a number on the box that corresponds to the level of colour: based on an international colour chart, the shades are arranged on a scale in which number 1 is BLACK and 10 is LIGHTEST BLOND.

It is crucial that you have an idea of your natural hair colour because you can choose your colour from a range that includes a few tones above it, and go darker, yet only one tone below, and go lighter. Let us give you an example: if your natural hair colour is a 7, i.e. BLOND, you could also choose a very dark colour, from 6 all the way down to include even black, however you can only “go up”, i.e. lighten, your hair by one tone, meaning a number 8 colour, which is LIGHT BLOND.

This issue of the numbers becomes more complicated because there is often a second and, at times, a third number alongside the first: these numbers indicate the reflect colour, which are the primary and secondary reflect colours respectively, and for this we also refer to the international chart.

For example, an 8.3 is GOLDEN LIGHT BLOND.

Another important thing you should know is that the colour shades are developed by formulators together with expert hair technicians, with initial tests of locks of hair and then on the heads of actual models, however the end result of the colour also depends on many variables related to the structure of our hair: finer or thicker, perhaps a little more porous, with a damaged cuticle, etc.

Permanent dyes are a type of cosmetics that are a little special, as they do not contain pigments (like make-up), but rather a series of molecules known as “intermediates” that react with one another, in the presence of hydrogen peroxide, to create the colour directly within the hair shaft. The dyes used in hair colours are some of the most meticulously studied substances and their safety has been demonstrated by numerous scientific studies, however they are substances that can cause serious allergic reactions, the most infamous of which is p-Phenylenediamine.

The problem is that this substance is one of the main intermediates used in hair dyes and, without it, you cannot get darker colours. However, alternative substances can be used to improve the tolerability and thus formulate hair dyes with a considerably lower risk of allergies to guarantee maximum tolerability.

As with other special cosmetics, the safety of hair dyes also depends on strict compliance with the instructions and warnings, including the recommendation to carry out a patch test first.

THE ALLERGY TEST is also called a “patch test” and involves applying a small amount of product (only the part of the dye that is used to “colour” the hair) on a small area of your skin. This is a simple test and it is recommended every time you dye your hair (48 hours before), even if you are using the same brand and the same shade, as individual sensitivity to the ingredients can change over time. A lack of reaction to this test provides reasonable safety in using the product.

Dying your hair at home is convenient, however doing everything alone means you need to be organised and be patient when reading and following all the precautions and instructions step-by-step. Most importantly of all, keep in mind the time it should be left on that is indicated on the packaging.

Permanent dyes are single-use products (therefore they do not have a PAO), so when you use them you need to mix the two components of the dye together completely: the dye cream with the hydrogen peroxide-based developer.

It has a standard format, so one box should be enough to dye a full head of medium-length hair. If you have long hair, you will need two boxes, while - conversely - if you have short hair, a little of the mixture will be left over, however this does not mean you should keep it for a second application.

We recommend waiting at least 3-4 weeks between hair dyes, because even if they are developed to be highly tolerable, dying still lightly stresses your hair.

When pregnant (particularly in the first trimester) and breastfeeding, we do not recommend using hair dyes. This is merely precautionary, as pregnancy is a time of change when your skin can also be more sensitive to certain substances.