Posted by Adria Marshall on

Understanding humectants in hair care can be more complex than it seems. These substances play a crucial role in adding or reducing moisture in the hair. However, there is a significant level of misunderstanding surrounding humectants due to their intricate relationship with the environment. Curious to learn more? Let's delve into the fascinating world of humectants and their impact on hair!

There are 5 categories of humectants:

  • Diols and Triols (e.g., Glycerin, Propylene glycol)
  • Hydrolyzed proteins (e.g., Keratin, Silk protein)
  • Esthers (e.g., PEG-x, Silicone Copolyols)
  • Sugars (e.g., Honey, Sorbitol).

Where it gets interesting is when attempting to grasp how these materials interact with the air. There are actually 4 scenarios that we need to consider to have a complete understanding of humectants.

Normal dew point conditions

When the dew point is... (Wait, what point? What is a dew point?) I'm so glad you asked! The dew point is the temperature in which water vapor begins to condense. Note: this is NOT the same as the humidity! Humidity is simply the amount of moisture in the air.

To calculate the dew point, you can:

1. Use this formula: Td = T - ((100 - RH)/5.) where Td is dew point temperature (in degrees Celsius), T is observed temperature (in degrees Celsius), and RH is relative humidity (in percent)

2. Go here (You're welcome)

So, as I was saying, when the dew point is 35 to 50 degrees F, it is considered normal, as far as our hair is concerned. There is just enough moisture in the air where the humectants in our hair can grab what they need to keep our hair bouncy and supple.

What to do? Not much - use product with a normal amount of humectants and keep it pushin'.


High dew point conditions

When the dew point rises above 60 degrees F, it's considered high and can have a significant impact on our hair. During these conditions, the humectants in our hair tend to attract excessive moisture, leading to a swollen cuticle and frizzy, poofy hair. 

So, what can you do? It's essential to reduce the use of humectants in your hair care routine. Additionally, applying oils or anti-humectant products can help protect your hair shaft from over-absorption.

Low dew point conditions

When the dew point drops below 30 degrees F, it's considered low and can have adverse effects on our hair. In these conditions, the humectants in our hair can actually draw moisture out of the hair and into the environment, leaving it even drier than before the humectant was applied. 

So, what should you do? It's important to reduce the use of humectants in your hair care routine during low dew point conditions. Additionally, incorporating oils or anti-humectant products can help prevent moisture loss and maintain hydration in your hair.

I hope that this blog help to demystify this subject a bit! What are your favorite humectants? How do you handle using them in various dew points? 



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  • Thank you so much! I have read so much about humectants and dew points in the past and gave up. THIS article gave me the “aha!” moment. It gets right to the point and I actually understand it now.

    Ella on
  • why do you use degrees Celsius in the calculation and for the effect on your hair Fahrenheit?
    you get a completely different number from the sum than the degrees you have outside. It’s a shame because I’ve been looking for this info for a while.

    Lonneke Verberne on
  • Duidelijk overzicht, dankjewel

    pieter on
  • This was very helpful and easy to understand.
    Thank you

    Beverly Bilbro on

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