First off, understand the work of the humectant: The one true job of a humectant is to absorb moisture and keep a moisture balance in the hair and skin. Humectants will search for moisture in your own hair too. Therefore, in areas where it may be hot, but dry, these products may actually do more bad than good.
Are Humectants Good or Bad?
It depends. In areas where the moisture and humidity is very high, (areas that tend to be very wet), combined with the heat of the summer, humectants can overdo their job by absorbing so much moisture that the hair becomes “bloated.” This leads to puffy, frizzy hair, instead of well defined curls and waves.
It's All About Dew Points
Understanding dew points can be a deciding factor in figuring out when to use humectants and when to avoid them.
The definition of dew point: the temperature at which a vapor (as water) begins or would begin to condense
Please note: this is referring to degrees in terms of the dew point, not how hot or cold it is.
Dry Dew Point: 15-30 degrees (-1 C)
Typically the winter months.
Use leave in conditioners.
Use light hold products.
Use plenty of emollients (moisturizing oils, butters).
Mid-Range Dew Point: 30-40 degrees (-1 to 4 C)
In between seasons, this will require trial and error to see what your hair likes.
- Some curls tolerate humectants in this range, some don't.
- Use emollients.
Best Dew Point for Curls: 40-60 degrees (4 to 16 C)
You will enjoy the best curls at this dew point.
Keep your hair moisturized.
- Humectants can be used.
- Use emollients.
High Dew Point: 60 (16C ) +
May skip a leave in conditioner.
Hard hold products like gels. You will want to control your hair.
May want to avoid humectants.
- Propylene Glycol
- Agave nectar
- Sodium PCA
- Hydrolyzed silk protein
After you better understand your climate and weather conditions, and your hair needs, you should also become aware of some of the more common humectants in products today.
A more detailed list of humectants in hair care products can be found in this article.
With this information, you can now go through the products you may already own, or, take into consideration some new ones, for your hair type. Take into account the season and area you are in to make better decisions on what to use and when. Of course, as in most cases, you may have to experiment with new or different products at various times of your summer, as the weather varies. Don’t give up on a product after just one use as it doesn’t necessarily mean that it won’t work - the weather may be the root of the issue.
Waterlily716 gives a thorough description in her YouTube video: