What is a film-forming humectant? It's a term for a group of ingredients that are moisturizers par excellence! Especially for hair that is easily weighed down by conditioners, or hair that oils or conditioners seem to sit on top of instead of "soak in." There is a list near the end of this page of products emphasizing film-forming humectants. ©Science-y Hair Blog 2014
Rather than just attract water when water is abundant like glycerin or sorbitol do, film-forming humectants form a film over your hair that helps your hair resist dehydration. ©Science-y Hair Blog 2014
Humectant ingredients in products (once the hair is dry) can release the water they initially attracted when the air when the air around your hair is dry. Some humectants release water fairly readily like glycerin or sorbitol. When humectants form a film, water is slowed down by needing to pass through the film, therefore water loss from your hair to the air around it is slowed.
With film-forming humectants, water is lost slowly from the hair through the humectant film over the course of the day or between washes because these are large, complex molecules which dry to form a clear, flexible film over your hair. Because they are very complex molecules they have more nooks and crannies for water to be packed into whereas a simple humectant molecule (like glycerin or propylene glycol) has fewer. Chemically, that's an oversimplification - but you get the idea. They not only trap water in themselves and in/around your hair - but the water has to pass through the film to escape from your hair.
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| Glycerin - a simple humectant molecule. |
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| D-Galacturonic acid, one of the several complex molecules in flax- seed gels. |
Analogy: If a simple humectant like glycerin dries quickly like an old, thin dish towel, then a film-forming humectant dries slowly like a very thick, plush bath towel.
Film forming humectants are often what your hair is needing when it seems dry even though you use oil or lots of conditioner or leave-in conditioner because they actively grab water and they keep their grip on it. If you want to keep your hair hydrated - a film-forming humectant in your leave-on or refreshing or moisturizing product is a necessity in a well-formulated product or product combination.
Where do film-forming humectants come from?
1) Plant gels©Science-y Hair Blog 2014
Many film-forming humectants are plant gels extracted from plant tissues. Plants excel at being able to store and move water. These all have a gel-like or juicy quality, tend to be slippery and to dry clear and smooth. Some work better in combination with others than alone.
- flax seed gel (linseed)
- okra gel (made from okra seed pods)
- aloe vera
- hydroxyethylcellulose
- pectin
- xanthan gum
- guar gum
- marsh mallow root
- slippery elm
- carrageenan (irish moss or seaweed extract)
- nettle leaf tea or nettle extract
- panthenol
2) Hydrolyzed proteins
Proteins from plant and animal sources also act like humectants, with smaller to medium proteins tending to get under the cuticles somewhat to moisturize/hydrate from the inside (or at least around the outside of the inside) and medium to large proteins forming clear films over the hair. All sizes of protein help slow water loss from the hair over the day.©Science-y Hair Blog 2014
What are film-forming humectants good in? Conditioners, leave-in conditioners, hair styling products, shampoos. Hydrolyzed proteins will stay with your hair even if they were used in a rinse-out conditioner. With most non-protein film-formers, you need to leave them in your hair to have them work the best at sealing in that water.©Science-y Hair Blog 2014
Can you use film-forming humectants with oil sealants? Absolutely! They compliment each other.
Oils as sealants on wet hair give you a waterproof barrier to water escaping from your hair. That's one sort of protection from dehydration - waterproofing. But oils are oily whereas film-forming humectants are more juicy and give you a water-soluble but strongly water-attracting layer. If you use both, you increase the likelihood that your hair will stay hydrated longer.
Something like a leave-in conditioner with a film-forming humectant could go over or under a layer of oil for sealing. A styling product with film-forming humectants can go over a layer of oil to seal. If you hair needs all the help it can get to stay hydrated and flexible, try all 3. Or mix everything together if applying more than one product seems like to much bother.©Science-y Hair Blog 2014
Something like a leave-in conditioner with a film-forming humectant could go over or under a layer of oil for sealing. A styling product with film-forming humectants can go over a layer of oil to seal. If you hair needs all the help it can get to stay hydrated and flexible, try all 3. Or mix everything together if applying more than one product seems like to much bother.©Science-y Hair Blog 2014
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