How can you wash your hair without water?

Hello, this is Science Popularization China. I don't know if you have seen something called "dry hair spray", but it seems quite novel to me. It is said that just spraying this spray on your hair will make it fluffy and less oily, which is almost the same as washing your hair. Today we are going to talk about how this dry hair spray works.
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In fact, the process of dry hair spray working can be simply described as "combination, adsorption, condensation, and shedding". Let's talk about it one by one.

First, in the combination stage, a surfactant in the dry hair spray will combine with the oil. We spray the spray evenly on the hair, grab and rub it with our hands, and the surfactant (usually high-grade fatty acid salt) can dissolve the oil molecules on the hair in the water.

At the same time, the dry hair spray will form some white powder on the head, which is the adsorbent that absorbs the oil condensation and surfactant. When the powder falls off from the hair, the purpose of removing oil can be achieved.

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You may be worried about whether this spray will have adverse effects on the body? In fact, dry hair spray is basically harmless, and the entire cleaning process is basically equivalent to dry shampooing. It's just that dry hair spray uses adsorption, gel, and sedimentation instead of water washing. The main ingredients are also the ingredients contained in soap and shampoo.

But when using it, we should avoid spraying dry hair spray in the eyes. Also, the butane, ethanol and other ingredients in it have the risk of explosion, so when using dry hair spray, stay away from fire.

Having said that, we have explained the principle of "dry shampooing" clearly. See you next time.

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Reviewer: Liu Lu, Professor of Organic Chemistry, School of Chemistry and Molecular Engineering, East China Normal University