As we move into spring and summer — our favorite seasons for fun outdoor activities — we face challenges with our curly hair that are unique to the climate and activities. Here is a great reader question that I will use as a springboard (no pun intended”> to offer some curly hair tips for protecting your curls in warmer, more humid weather. This column is written more from my scientist perspective than an ingredients-chemistry perspective, in case you were wondering!

Q: All winter, my hair behaved. My hair is thin, but there is lots of it! It loves mousse and a little conditioner. Now that it’s humid, my hair is misbehaving. What do I do? More conditioner? Gel instead of mousse? I like to elongate my curls as much as possible, they can get tight. Any help would be much appreciated!

A: There’s no denying that the change change in seasons can be tough on our hair care routines. Products and processes that were working so well suddenly seem to have the opposite effect. Often, at the heart of these issues is a change in the environmental moisture content (humidity”>. High humidity is especially harsh on curly hair.

The reason for its susceptibility to humidity fluctuations lies in the physical structure of curly hair. Straight hair, undamaged by environmental or treatment factors, has a protective outer layer of cuticle scales that overlap and lie fairly flat against one another. Curly hair, even in very good condition, is much more porous because those cuticle scales do not always lie flat. This porosity allows more water to migrate out of curly hair into the environment in dry weather (not good”>, and also allows more moisture from the environment to migrate into the cortex of the hair strands in humid weather (also not good”>.

Absorption of water into the hair from the environment works to disrupt hydrogen bonds between adjacent hairs, which can diminish curl clumping and definition and lead to flyaway hair and a frizzy appearance. This absorption of moisture can also cause the hair shaft to swell and ruffle up the cuticles a bit, which can lead to tangling, an unpleasant overall texture, and more frizz. Hair strands swollen with water, and with ruffled cuticles because of water absorption, are also more delicate, and can more easily be damaged or broken.

Here are two scanning electron micrograph images of single human hair strands. The one on the left is smooth and shows a cuticle layer in excellent condition. The image to the right shows a damaged cuticle layer, with raised scales, chipped cuticle scales, and spots where the cuticle has been completely removed.

Absorption of water from the air into the central core of each hair strand is much more pronounced in hair that has even greater porosity because of raised or damaged cuticles. Chemical treatments, such as coloring and perming, as well as the use of thermal styling tools (hair dryers, hot rollers, curling irons”> or rough combing or brushing, frequent exposure to sunshine, and even tossing and turning in our sleep can all damage these cuticles and increase the porosity of curly hair.

The process also occurs to a greater extent if the hair needs hydration. For this reason, it is very important to maintain hair in the best condition possible at all times, but especially in warm and humid weather. In warm, wet weather, keep your hair very well-moisturized and use a good leave-in conditioner, but try to avoid using products that include humectants in their ingredients, as these can aggravate problems with humidity-induced frizz. Styling gels seem to perform better in this type of weather than mousse. The polymer styling agents in gels form a nice protective film around the hair, which helps maintain the style throughout the day.

Curly hair tips for lovely summer locks:

  • Trim hair regularly
  • Avoid using thermal drying and styling techniques
  • Gently finger comb or use a wide-toothed comb on wet hair that is saturated with conditioner
  • Be selective about chemical treatments on the hair — minimize the frequency of such processes
  • Avoid frequent exposure to direct sunlight — wear a hat or use a leave-in product containing sunscreens for the hair
  • Use generous amounts of moisturizing products, both in the shower and as leave-in treatments. (This reduces diffusion of moisture into and out of the hair”>
  • Consider using a low-viscosity, easily spreadable hair gel as your primary styling agent for the summer.
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