Which surfactant?

As you all know I’m doing the Formula Botanica Diploma of Organic Skin Care Formulation, and for the past few weeks I’ve been playing around with hydrosols and looking into hydrous skin care products, such as toners, micellar waters and gels.

I’ve now gone from the basics (simple toners and simple gels) to slightly more complex micellar waters. What are micellar waters? These popular 3-in-1 cleansers are not only great as cleansers, they also tone and re-hydrate at the same time. Micellar waters are a blend of water or hydrosols, humectants and surfactants, which help remove both water-soluble and oil-soluble dirt and grime from your skin. They are one of the mildest and gentlest forms of cleansers available and particularly suitable for sensitive skins types.

After making a few different micellar waters, I wanted to know how specific surfactants used in the different formulations change the feel and look of the micellar waters. So I decided to take a closer look at them and test them with just water and without the other ingredients affecting the results.

The 4 ingredients that I tested are cocamidopropyl betaine, coco-glucoside, capric/caprylic glucoside and kumerahou extract, which I included because of its high saponin content. These are all natural ingredients, and apart from the kumerahou extract, you’ll find them in a lot of diy skin care recipes on the internet. The reason I chose these particular four is because they are readily available here in New Zealand and I got mine from Pure Nature.

Testing the surfactants

What I wanted to test for are two things: clarity of the liquid and soapy feel on your skin (which I’m not particularly a fan of). I decided to use the maximum usage rate for in a micellar water, because it will also tell me a little bit more about the general surfactant properties of each ingredient in water, for possible later use in other products (thinking natural household cleaning products!)

I tested each ingredient by making the same formulation for each:

95% distilled water
5% surfactant

So here are the results.

Cocamidopropyl betaine

Cocamidopropyl betaine

Cocamidopropyl betaine is an amphoteric surfactant, and the one from Pure Nature is naturally derived from coconut (palm-free). Amphoteric means it has both anionic (cleansing) and cationic (conditioning) properties depending on the pH of the product. At lower pH it will become more conditioning. But in water, it is used for its mild cleansing abilities.

When I mixed the cocamidopropyl betaine with water, the resulting liquid remained fully clear and you could see bubbles on the surface. It foamed up on my skin, but had a slightly less soapy feel to it than the two glucosides I tested, and it left my skin feeling nice and soft after it dried.

Coco-glucoside

Coco-glucoside

Coco-glucoside is a non-ionic surfactant derived from coconut oil and corn sugars. It is a very viscous liquid, and when I stirred it into water, it left the water cloudy/milky.

Coco-glucoside has a very soapy feel to it when I applied it on my skin and it left my skin feeling rather tight after drying. It’s possible that this would lessen if I used it in a lower concentration, but of all four ingredients, this one would be my least favourite one to use in a micellar water. I think it’s more suitable for a rinse-off cleansing product, if you don’t mind a milky liquid.

Capric/caprylic glucoside

Capric/caprylic glucoside

This is another glucoside, also derived from coconut oil and corn sugars, but unlike coco-glucoside, capric/caprylic glucoside added to water results in a very clear liquid.

However, it also foamed when applied to the skin, and also felt very soapy, and again, it left my skin feeling tight when it dried.

Like coco-glucoside, capric/caprylic glucoside is another ingredient to use in rinse-off cleansing products for the skin or even in household cleaning products, as it foams up the most (more than coco-glucoside).

Kumerahou extract

Kumerahou extract

As I mentioned above, I included kumerahou extract because of its high saponin content. Saponins are like a soap from nature and you can find them in some plants, like soapwort (which is why soapwort is called soapwort). Saponins have similar properties to soap, meaning they lather up and have a soapy feel to it.

Kumerahou is a native New Zealand plant, and I’m sure you can make your own kumerahou extract, I bought mine from Pure Nature.

The kumerahou extract I bought has an INCI of Glycerol, Pomaderris Kumerahou (Kumerahou) Leaf Extract, Water. This is a glycerine infusion, which is water-soluble and exactly what I need (saponins are water soluble).

The extract is a golden-brown and very viscous liquid, and when I stirred it into the water it tinged the water a golden-yellow colour, but left it very clear and transparent.

Also despite the bubbles on the surface, like the other surfactants I tested, it didn’t have a soapy feel when I applied it to my skin and didn’t foam. However, my skin did feel a bit tight after drying, but only a touch.

I have to admit, I wasn’t expecting much, so it was a surprisingly nice find for me. I would definitely recommend using this in micellar waters or other skin care cleansing products.

So here are the results in a table:

Ingredient– Clarity – Colour Bubbles
when stirred
Foams when
applied to skin
Feel on skin
Cocamidopropyl betaineclearclearyesyesslightly soapy
skin feels soft
Coco-glucosidecloudymilkyyesyessoapy feel
skin feels tight
Capric/caprylic glucosideclearclearyes, the mostyes, the mostsoapy feel
skin feels tight
Kumerahou extractcleargoldenyes, the leastnono soapy feel
skin feels
a little bit tight
From left to right: Kumerahou extract, capric/caprylic glucoside, coco-glucoside, cocamidopropyl betaine.

If you check back tomorrow, I’ll be posting a beautiful kumerahou and manuka micellar water, suitable for all skin types, but especially sensitive, irritated and dry skins.


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