What are the effects of sunscreen and how to use it correctly? How to choose the sunscreen that suits you?

Classification of sunscreen

Sunscreen refers to cosmetics added with sunscreen agents that can block or absorb ultraviolet rays to prevent skin from tanning and sunburn. According to the principle of sun protection, sunscreen can be divided into physical sunscreen and chemical sunscreen.

Physical sunscreen

Physical sunscreen, as the name suggests, uses the principles of physics. The atomic particles of this sunscreen are flake-shaped. When spread on the face, they act like a mirror, reflecting sunlight to achieve the purpose of sun protection. Titanium dioxide and zinc oxide are both physical sunscreen ingredients. They can form a protective film on the skin so that ultraviolet rays cannot penetrate the skin surface. Both can provide comprehensive UVB protection, among which zinc oxide can block UVA better. Typical physical sunscreen ingredients are white and pasty, and turn blue when exposed to water. However, this type of product also has certain limitations: for people with darker skin, the polishing effect may not be natural; for people with drier skin, it is not moisturizing enough; it is not suitable for full-body sunscreen; makeup remover products must be used to help Remove it clean, etc.

chemical sunscreen

Chemical sunscreen is to use chemical ingredients to protect from the sun. This kind of sunscreen uses the principle of absorption to protect from the sun. It is a light-transmitting substance that can absorb ultraviolet rays and convert them into molecular vibration energy or heat energy to achieve the effect of sun protection, such as amino acids. Benzoic acid and its derivatives, cinnamic acid, etc. When applied to the face, the atoms absorb sunlight to prevent it from reaching the skin. In theory, physical sunscreen is better than chemical sunscreen, but currently most of them on the market are chemical sunscreens.

Classification of sunscreen

Sunscreen refers to cosmetics added with sunscreen agents that can block or absorb ultraviolet rays to prevent skin from tanning and sunburn. According to the principle of sun protection, sunscreen can be divided into physical sunscreen and chemical sunscreen.

Physical sunscreen

Physical sunscreen, as the name suggests, uses the principles of physics. The atomic particles of this sunscreen are flake-shaped. When spread on the face, they act like a mirror, reflecting sunlight to achieve the purpose of sun protection. Titanium dioxide and zinc oxide are both physical sunscreen ingredients. They can form a protective film on the skin so that ultraviolet rays cannot penetrate the skin surface. Both can provide comprehensive UVB protection, among which zinc oxide can block UVA better. Typical physical sunscreen ingredients are white and pasty, and turn blue when exposed to water. However, this type of product also has certain limitations: for people with darker skin, the polishing effect may not be natural; for people with drier skin, it is not moisturizing enough; it is not suitable for full-body sunscreen; makeup remover products must be used to help Remove it clean, etc.

chemical sunscreen

Chemical sunscreen is to use chemical ingredients to protect from the sun. This kind of sunscreen uses the principle of absorption to protect from the sun. It is a light-transmitting substance that can absorb ultraviolet rays and convert them into molecular vibration energy or heat energy to achieve the effect of sun protection, such as amino acids. Benzoic acid and its derivatives, cinnamic acid, etc. When applied to the face, the atoms absorb sunlight to prevent it from reaching the skin. In theory, physical sunscreen is better than chemical sunscreen, but currently most of them on the market are chemical sunscreens.

Precautions for using sunscreen

1. Application area

When applying sunscreen, don't neglect your neck, chin, ears and other areas to avoid uneven skin tone.

2. Cleaning products

Be sure to remove sunscreen completely every night, so don't rest and sleep with it on.

3. Use enough amount

Sunscreen is not effective just by applying it, but it must reach a certain amount to be effective. Usually, the amount of sunscreen applied on the skin is 2 mg per square centimeter to achieve the desired sun protection effect. It should be noted that SPF values cannot be accumulated. Applying two layers of SPF10 sunscreen will only have the protective effect of one layer of SPF10.

4. Do not mix sunscreens from different brands

Mixed use can increase the likelihood of skin irritation. The ingredients of sunscreens of various brands are inconsistent. If they are mixed and overlapped on the skin, the ingredients may interfere with or exclude each other, reduce the sunscreen effect, and even cause skin allergies.

5. Pay attention to saving

Sunscreen may be less effective if exposed to heat or direct sunlight for a long time. Do not use spoiled sunscreen cosmetics as it not only reduces the sunscreen effect but is also more likely to irritate the skin.

6. Pay attention to sun protection blind spots

When applying ordinary sunscreen, you also need to pay attention to the skin of your eyes and lips. However, if there is no instruction, or if you use sunscreen products for the eyes, do not use it on the skin around the eyes.

Different skin types, different purchasing methods

In summer, skin texture will change due to differences in oil secretion. Therefore, people should do another accurate skin test before purchasing. Oily skin should choose water-based sunscreen products with strong penetration; dry skin should choose cream-type sunscreen products; there are generally no strict regulations for neutral skin, and emulsion-type sunscreen is suitable for all types of skin. Different skin types should choose different sunscreens

Oily skin:

You should choose a water-based, oil-free formula sunscreen with strong penetrating power, which is refreshing and non-greasy to use and does not clog pores. Never use sunscreen oil, and use physical sunscreen products with caution.

Acne-type skin:

Choose a water-based, oil-free sunscreen with strong penetrating power. When acne is severe, you should stop using sunscreen, and you can only use physical methods of covering up when going out.

Dry skin:

People with dry skin must choose sunscreen that is moisturizing in texture and has added hydrating effects and enhances skin immunity. Many sunscreens have added hydrating and antioxidant effects in addition to sun protection.

Sensitive skin:

For sensitive skin, it is recommended to choose sunscreen specially formulated for sensitive skin or physical sunscreen.

SPF

Nowadays, all sunscreen products are specifically labeled with SPF. SPF and the following numbers indicate the sun protection factor the product has. Consumers can convert the SPF value of the sunscreen they need to buy by themselves. Most people will look at the SPF value as the main parameter of sunscreen. SPF is the English abbreviation of SUN proteetion Factor. This indicates how high or low the sunscreen can be in preventing sunscreen. SPF parameter: SPF=minimum erythema dose (after using sunscreen products) )/minimum erythema dose (before using sunscreen).

For example, if your skin has a minimum erythema dose of 15 minutes, if you use sunscreen with SPF 4, you can theoretically stay in the sun for 4 times as long, which is 60 minutes. After 60 minutes, your skin will turn reddish. . If you are using SPF8 sunscreen, you can stay in the sun for 8 times that is 120 minutes, and so on.

Generally speaking, the higher the SPF index, the greater the protection it provides. Under normal circumstances, people with normal skin types should use sunscreens with SPF 8 to 12; those with fair skin should use SPF 30; people with photosensitivity should choose sunscreens with an SPF value between 12 and 20. Office workers only come into contact with the sun on their way to and from get off work, so the SPF should be below 15. For tourists who engage in outdoor activities, it is recommended to use sunscreen with SPF20 or so. When exercising under the scorching sun on the plateau or swimming at the beach, you should use SPF30 sunscreen. It is advisable to choose waterproof sunscreen skin care products when swimming outdoors, but except for swimming, waterproof sunscreen skin care products should be used sparingly.

Precautions when purchasing

1. Skin test

It is recommended to do an accurate skin test before purchasing sunscreen. Oily skin should choose water-based sunscreen with strong penetration; dry skin should choose cream sunscreen; medium skin generally has no strict requirements, and emulsion-type sunscreen is suitable for all types of skin.

2. Calculate SPF value

Generally speaking, the higher the SPF index, the longer the protection time given.

3. Understand the suitable groups for different sunscreens

Different sunscreen products are suitable for different people. The best way is to try them on the inside of your wrist before buying. If the skin becomes red, swollen, painful, or itchy within 10 minutes, it means you have an allergic reaction to the product. You can try a product with a SPF that is one times lower than this. If there is still a reaction, it is best to give up that brand of sunscreen.

4. Skin quality testing

Due to differences in oil secretion, skin quality will change, so a skin quality test should be done. Oily skin should choose foam cleansers with strong cleansing power and water-based sunscreen products with strong penetration; dry skin should choose milky cleansers and cream sunscreen products; neutral skin has a wider range of options. Lotion and spray sunscreens are basically suitable for all skin types.