Rain Ruining Hair

Woman with an umbrella to protect her hair
Photo: Peppersmint/Shutterstock
Q: What is the scientific explanation behind women’s hair getting ruined by rain? Why does this happen?
 
A: Most women style their hair in some sort of manner. This mostly includes manual heat-styling processes such as blow-drying, curling or flat-ironing the hair. Even if you just hang your head upside down and give it a quick blow-over with a hair-dryer, you’re still heat-styling it.
 
The heat decreases the amount of water or humidity in the structure of the hair to a greater or lesser extent, depending on which type of method you’re using. When you just give it a quick blow with the hair-dryer, you don’t reduce the water content in the structure as much as when you do a full blow-dry followed by straightening the hair.
 
When you do the full service, (blow-drying followed by straightening), the hair loses most of its structural humidity, while it will be styled to look perfectly straight. This method is most commonly used on clients who have very curly, unmanageable or unruly hair.
 
Thus, the more heat you apply to the hair will result in a straighter style, with a proportionally decreased amount of water-content left in the hair. The structure of the hair tends to absorb water when it gets wet or is exposed to a humid environment.
 
As you’re asking for the “scientific” explanation of this phenomenon, you’re most probably well aware of the law of diffusion. This law states that all other things being equal, particles will always move spontaneously from a high concentration to a lower concentration.
 
In this case, the water particles in humid air or rainy weather will move from the high water-content environment/atmosphere to the comparatively low water-content of the hair’s structure. This is especially the case in hair that has been blow-dried or flat-ironed, as most of the natural water-content has been removed from the hair’s structure in order to get looking straight and shiny.
 
The moment the water particles enter and cling to the inner structure of the hair, the hair shaft swells, and automatically returns to its natural form. Thus, if you naturally have very curly or frizzy hair, the added water content will transform the hair back to its natural form. Because the hair also absorbs the extra water, it swells inadvertently, meaning that the hair will look even more puffy, curly or frizzy than normal. There’s really nothing to keep the hair from reacting in this manner when it is exposed to wet or humid weather.
 
If the hair is only marginally humid, you can apply a small amount of silicone based smoothing lotion or a gloss hairspray to the hair. This will block out humidity to a certain extent, willing that the air is only marginally humid. Just remember that these are very heavy products, and will involuntarily cause very fine or thin hair to fall flat because of the excess weight.
 
Your best bet is to wear a slicked-back style in this kind of weather. A very sleek and pulled back ponytail or slicking the hair with styling gel and creating old school finger waves work perfectly for these occasions.
 
©Hairfinder.com
 
See also:
 
How to maintain your hairstyle in humid weather
 
Why is rain such a disaster for a woman's hair?
 
Why does my hair retain so much heat?