The Spring Festival is approaching, many people will make a new look to welcome the New Year, and more people dye and perm their hair.
Pure natural, pure plant, good coloring, no fading... There are many types of hair coloring products on the market, and to choose a safe and effective hair dye that meets your personal needs, you must first understand their characteristics.
Experts interviewed
You Yan, member of the Medical Aesthetics and Cosmetology Branch of the Chinese Medical Association
Professor of Dermatology, Southwest Hospital, Army Medical University Yang Xichuan
Before dyeing your hair, look at the hair dye ingredients
Hair dye can be divided into temporary hair dyes, semi-permanent hair dye, and permanent hair dye.
Temporary hair dyes
Washed with shampoo can be removed, its particles are large, can not enter the hair root through the epidermis, but deposited on the surface of the hair to form a coloring overlay, so it is relatively safe, but the dyeing power is not strong, easy to be washed off.
Semi-permanent hair dye
The color is "hanged" on the surface of the hair, which can be washed by shampoo 6~12 times, and generally applied to the hair for 20~30 minutes before coloring.
Since there is no need to use hydrogen peroxide, hair damage is reduced, so it has become more popular in recent years.
Permanent hair dye
This is the most used hair dye, mainly divided into three types: synthetic hair dye (oxidized hair dye), natural hair dye, inorganic hair dye (metal hair dye).
◎Synthetic hair dyes
It is the mainstream product on the market at present, usually using hydrogen peroxide to destroy the melanin of the hair, so that the hair is decolorized and lightened, and then using intermediate agents such as p-phenylenediamine to attach various colors of dyes to the hair.
Hydrogen peroxide has strong irritation to the skin, and contact with broken skin will cause obvious pain; p-phenylenediamine is a common allergen, and most hair dye allergies are caused by it, and it is recommended to use it no more than twice a year.
◎Natural hair dye
Although healthy and safe, the price is high and the market share is small.
It is made from raw materials extracted from natural organisms, such as substances extracted from the flowers, stems and leaves of plants for dyeing, which has little damage to the human body and the environment, but the coloring strength is relatively poor.
◎Inorganic hair dye
Due to the great harm to the human body, it is already difficult to see on the market now, and it is not recommended to use it.
It is mainly used for dyeing black hair with white hair, and the mechanism of action is to apply silver nitrate solution and sodium sulfide solution to the hair to generate black silver sulfide attached to the hair; There are also compounds containing lead, iron, copper and other metals that interact with the sulfur in hemisarcosine in hair proteins to produce black lead sulfide.
Repeated use of such hair dyes can cause heavy metal accumulation poisoning, aplastic anemia, hypertension, nervous system damage, etc.
Injury comparison of different hair dyes
What exactly happens to hair when you dye it?
Take permanent hair dye as an example:
In the process of dyeing hair, the dye liquid first opens the outermost layer of hair scales, enters the inside of the hair through the opened holes, and then removes melanin and oxidizes with the colorant to color the hair.
Subsequently, the oxidant and the coupling agent undergo oxidation reaction and condensation reaction to form larger dye molecules, which are enclosed in the hair fiber and form a color development effect on the hair color.
Normal hair above vs hair after dyeing below
When the hair scales are closed, the hair is naturally shiny, and the damage to the hair scales will make the hair lose its luster, deteriorate hair quality, and even dry and break.
In general, the longer the hair dye lasts, the more damage it will cause to the hair.
From the point of view of damage to hair, permanent hair dye > temporary and semi-permanent. If you want to reduce hair damage, you can choose temporary hair dye or semi-permanent hair dye.
Some hair dyes claim to use Chinese herbs or botanical ingredients and can be used daily just like regular shampoos. In fact, these products may also contain hair dye ingredients, which is not the same as natural.
Do not trust advertising slogans and hairdressing agencies, pay attention to the label ingredients, especially if you are allergic to a certain ingredient in cosmetics, you should avoid choosing products containing this ingredient.
Dermatologists summarize the details of safe hair coloring
In addition to controlling the frequency of hair coloring, what else should I pay attention to?
Choose regular high-quality products
Production process, refining technology, material formula, etc. will affect the effect and side effects of hair dye, so try to choose regular and high-quality products within the scope of ability.
Apply some cream behind the hairline ears
It is recommended to apply petroleum jelly or cream lotion to the hairline and behind the ears before coloring the hair to prevent the hair dye from getting on the skin and causing damage.
At the salon, remind the hairstylist to try not to let the dye come into direct contact with the scalp. If you dye your hair at home, it is recommended to buy hair dye produced by regular manufacturers.
Do a skin test in advance
If you plan to dye your hair at home, make some preparations in advance to reduce the damage of hair dye.
Before dyeing hair, you can apply a little hair dye to the hair dye area or behind the ears, and observe for 24~48 hours (must meet this time range) for skin testing.
If you find redness, swelling, rash and other reactions on the local skin after the test, do not use the product to continue dyeing your hair.
In case of allergies, rinse in time
If you feel obvious itching, burning, swelling and other allergic symptoms after dyeing your hair, you can cover your face first, wear disposable gloves, and immediately rinse off the hair dye with warm water.
If the symptoms worsen, go to a regular hospital for treatment in time. If the symptoms are mild, they will generally be relieved and subsided slowly after stopping contact with the allergenic substance. ▲
Editor of this issue: Xu Menglian