Recently I downloaded an app for my Android from NaturallyCurly.com called Curls on the Go. What I love about this app, other than the wealth of information, is that it is able to tell me the temperature, humidity and dew point for my location, what that means for my hair (optimal or frizzy hair day) and what type of products I should use to have an optimal hair day. I thought to myself this is fantastic I will never have a bad hair day again, especially since my hair has started to grow and the products I used to use are just not working anymore. I knew what temperature and humidity was from experience. I know if the weather man says today will be 100 degrees with 90% humidity it’s going to be a nasty day. But I didn’t understand what a dew point was and how that affected my hair.
What I have found is the temperature, humidity and dew point can be the difference between and good or bad hair day and why humectants and anti humectants are important.
Relative Humidity is vapor pressure of water in the air at a specific time versus the saturated vapor pressure of water at that temperature. The saturated vapor pressure for water changes substantially with temperature; so as the temperature increases or decreases the value of relative humidity changes even if overall water content in the air remains unchanged. How does humidity affect hair? Well hair is largely hydroscopic, meaning it is able to exchange water molecules with moist or dry air. While dry air will drive water molecules from your hair into the environment, humidity has the opposite effect on hair. The hydroscopic nature of hair during humidity will prompt absorption of airborne moisture, which in turn causes swelling of the hair–as much as 16 percent of the diameter in high humidity. High Humidity is any percentage above 45 to 50.
Curly hair tends to be dry and therefore vulnerable to humid air. It simply wants to soak up moisture. This causes cuticles to expand, which causes frizz. The secret to keeping frizz at bay involves moisture, moisture, moisture. To keep hair properly moisturized, you need a few hair products including: non-sulfate shampoo, a leave-in conditioner, a deep conditioner and a styling product involving silicone.
Dew Point is the temperature at which the air can no longer hold all of its water vapor, and some of the water vapor must condense into liquid water. The dew point is always lower than (or equal to) the air temperature. While relative humidity is (as its name suggests) a relative measure of how humid the air is, the dew point temperature is an absolute measure of how much water vapor is in the air. In very warm, humid conditions, the dew point temperature often reaches 75 to 77 degrees F, and sometimes exceeds 80 degrees. No matter how hot the temperature gets, a dew point temperature of (say) 75 deg. F always represents the same amount of water vapor in the air. How does dew point affect hair? I have provided a chart that illustrates how dew point affects hair and what you can do to combat the affects.
Dew Point Below 15 F: Very Dry. Use as much moisture and emollients as your hair can handle without over conditioning. Humectants use may need to be cut out entirely or severely limited.
Dew Point 15-30 F: Dry, add moisture and emollients. Limit or cut out humectants.
Dew Point 30-40F: Can be Iffy, some people can tolerate more humectants. Others cannot, very trial and error in this range.
Dew Point 40-60 F: Prime curly range. You should get some curl without the summer frizz. Find balance between moisture and humectants that work for you.
Dew Point 60F and up: You need to find moisture/humectants tolerance that works for you. Some of you will be able to tolerate humectants. Those of you with porous hair may start to see humectants induced frizz at this range and especially once the dew point fits 70. Those who get humectants induced frizz may want to look into anti-humectants to keep that muggy weather out of your hair.
Humectants are molecules that possess atoms and groups of atoms that attract and bind water to themselves. They can have benefits and drawbacks for curly hair, and their performance is often very dependent upon the amount of moisture in the environment. Applied to the hair humectants draw water to themselves from whichever source is greater either the atmosphere or the hair so be careful
Anti-Humectants must not be hygroscopic, meaning it must not possess molecular traits that cause it to attract water molecules to itself. It must be water-repellent, which necessarily means insoluble in water. This property allows it to lock out or prevent the intrusion of moisture into the hair from a humid environment. Additionally, these ingredients typically coat, flatten, and seal the external cuticle layer of the hair strands.
So what did I learn? I’ve learned is that Temperature, Humidity and Dew Point are tools we use to learn how much water vapor is in the air which just means how much moisture is in the air. I know that I will have an awesome hair day if the humidity percentage is below 45 and if the dew point is in between 40-60 F. Yes my app can easily tell me if it’s going to be an optimal or frizzy hair day and what products I should use. But, I am the type of person that needs to understand the difference between a good and bad hair day. I hope this helps someone no one should have a bad hair day.