Dew Points

Hey Twisties,

The simple definition the dew point temperature is when the air becomes saturated with water and the point where water vapor condenses to liquid water. The dew point is an absolute measure of the water content in the air whereas the relativity humidity is directly dependent on the air temperature and will fluctuate with a change in temperature. The dew point temperature is a more accurate measure of the air’s water vapor content. The dew point will always be lower than or equal to the temperature, and the point where the air temperature and the dew point are equal, the relative humidity will be 100%.

Understanding the dew point can help curlies when deciding which type of products are going to hold up in the weather and help combat frizz a popular ingredient for this is a humectant.

Humectants posses the ability to draw moisture to itself. If a humectant is applied to the hair in a very humid environment, the humectant will pull moisture from the air to itself potentially overloading the hair shaft causing it to swell. Since the moisture drawing molecules are unbiased, in dry environments they can pull moisture from you hair, causing it to become dry. Sometimes humectants can work against the hair in extreme climate conditions.

Examples of Humectants provided by naturallycurly.com

Diols and Triols
Propylene glycol 1,2,6 hexanetriol Butylene Glycol Dipropylene glycol Hexylene Glycol Glycerin Triethylene glycol Erythritol Capryl glycol Phytantriol Hexanediol or -triol beeswax

Humectants of biological origin
Panthenol Sodium PCA Hyaluronic acid Inositol Glycogen

Sugars and modified sugars
Sorbitol Polyglyceryl sorbitol Glucose Fructose Xylitol

Hydrolyzed proteins
Elastin, Collagen Silk Keratin

Ethers
Isoceteth-x, Isolaureth-x, Laneth-x, Laureth-x, Steareth-x PEG-x (polyethylene glycol)Silicone copolyols

Below is a chart that I pulled of the internet to help give an understanding of what it may feel like at certain dew point temperatures.

Dew Point Temperature	Human Perception	Rel. Humidity at 90°
> 80°	Severely high. Even deadly for asthma related illnesses	65% and higher
75-80°	Extremely uncomfortable, fairly oppressive	62%
70-75°	Very humid, quite uncomfortable	52-60%
65-69°	Somewhat uncomfortable for most people at upper edge	44-52%
60-64°	Ok for most, but all perceive the humidity at upper edge	37-46%
55-59°	Comfortable	38-41%
50-54°	Very comfortable	31-37%
< 49°	A bit dry for some	30%

The higher the dew point the more moisture content is in the air. Our hair is constantly trying to establish equilibrium through the absorption or release of water molecules. If the moisture content in the air is higher than our hair, then the moisture will move from the air to the hair until it’s balanced. This is what causes the frizz effect during humid days. The reverse also applies. If the moisture content in our hair is greater than the dry air, moisture will be drawn away trying to establish equilibrium with the air. Below is a chart from TRI Princeton depicting the gain and loss of moisture in the hair in regards to the change in humidity.