The shampoo is gone, so you use shower gel to wash your hair? If you use them to wash your hair again, your hair may be ruined!

You must have had this experience: when you were taking a shower, you wanted to apply some shampoo to wash your hair, but accidentally applied some shower gel instead. After applying it, you didn’t want to waste it, so you applied the shower gel directly to your head, and found that it could still create bubbles and wash away the oil in your hair. Although it felt different from shampoo, it could still wash your hair clean.

So what is the difference between shampoo and shower gel? Can they be mixed together?

If you are using them just for basic degreasing and stain removal, then you can mix them together. This is because their basic ingredients are actually "surfactants"[1], and their molecular structure looks like this, similar to a matchstick.

Map: Science Popularization China New Media

When washing your hair or body, the "matchstick" of this "match" will insert into the oil, and multiple "matches" gathered together will form a circle of such "micelles", trapping the oil; at the same time, the "match heads" outside the "micelles" are closer to water molecules, and the "micelles" can easily dissolve in water and move with the water flow, leaving the surface of the body or hair, thereby achieving a cleansing effect.

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But although they follow the same cleaning principle, the cleaning effects of shampoo and shower gel are not exactly the same .

In shampoo, anionic surfactants are mainly used, which can increase the negative potential of dirt particles and the surface of hair, and utilize the principle of like charges repel each other to enhance the cleaning effect .

In addition to anionic surfactants, shower gels also use amphoteric surfactants . This type of surfactant is resistant to hard water [2] and can function normally even if there are a lot of calcium and magnesium ions in the bath water. In addition, amphoteric surfactants have strong emulsification and foaming properties , which can produce more foam, allowing oil to form an emulsion more fully and evenly and be washed away by water, so they are more suitable for use on the body surface.

But for hair, it is not enough to just clean the oil, it is equally important to ensure smooth hair.

On the microscopic surface of hair, there is a layer of scales[3], which is made up of many tiny scales stacked together. During the washing process, if the scales are damaged and curled up, the friction between the hair strands will increase, and the hair will appear dry, frizzy and lose its luster.

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In order to avoid this situation, many shampoos will add a substance called polydimethylsiloxane , commonly known as silicone oil. It can fill the damaged parts of the hair scales, form a protective film, and make the hair smoother and smoother.

Photo taken by: Xu Lai

So overall, shower gel and shampoo are not suitable for interchangeable use . Buying one less bottle to save money or trouble is not a good idea either.

Except for shampoo and shower gel, shampoo, shower gel, facial cleanser and soap are not suitable to be mixed together.

The surfactants used in some facial cleansers are amino acid surfactants , which are weakly acidic like your skin. Compared with shower gel and shampoo, they are milder and less irritating. They can protect the skin barrier while cleaning. If you just want to wash your face, it is recommended to use facial cleanser.

The problem with soap is that it is too strong in removing oil . Soap becomes alkaline after hydrolysis, and washing the body with it can easily irritate the skin and may also disrupt the skin's water-oil balance system , causing the skin to become overly dry and tight. Sometimes, in order to make up for the oil loss caused by soap, the skin will secrete more oil, causing your body to become oilier and greasy for a period of time after taking a shower than before taking a shower...

After all, each cleaning product is designed with different formulas because they have their own suitable scenarios. Only by doing their own job and doing what they are good at can they play the greatest role. If you insist on using a bottle of shower gel to wash your whole body, it is equivalent to asking a restaurant employee to be a cook, waiter, manager, and dishwasher at the same time: it is possible, but it is not necessary~

References:

[1] Meng Weihua, Liu Xianjun. A review of shampoo ingredients, formulation process and market overview[J]. China Detergent Industry, 2016(4):71-77. DOI:10.3969/j.issn.1672-2701.2016.04.008.
[2] Fang Yun, Xia Yongmei. Amphoteric surfactants (IV) General properties of amphoteric surfactants [J]. Surfactant Chemical Industry, 2000, 30(6): 47-50. DOI: 10.3969/j.issn.1001-1803.2000.06.014.
[3] Hu Xiuhong. Research on damage and protection of hair fibers[D]. Zhejiang: Zhejiang Sci-Tech University, 2009. DOI:10.7666/d.y1606189.

This film is a work supported by the Science Popularization China Starry Sky Project

Produced by: Chai Knows (Speaker: Wang Zhenxing, founder of "Chai Knows")

Reviewer: Gai Donghai, Vice President of China Detergent Industry Magazine

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

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