How solubilizers and emulsifiers work in skin care chemistry

What are Emulsifiers and Solubilizers?

Written by: | February 13, 2020 | 13 responses

Many industries have certain terms they use to help make communication easier. This jargon is great if you already understand the meaning, but it can be confusing if you’re just getting started. Emulsifiers and solubilizers are important ingredients in making hair and skincare products, so it’s beneficial to know what those terms mean and how to identify those ingredients when reading the ingredient deck on your favorite products!

Emulsifiers

Simply put, an emulsion is the suspension of one liquid in another liquid. There are more technical definitions, but to explain what an emulsifier does, let’s stick with this simple explanation. Lotions, creams, and conditioners are all examples of emulsions. In these examples tiny droplets of oil are suspended in water.  If you were to take a bottle and fill it 1/2 full of water and then fill the rest with oil, you would quickly notice the two don’t mix. However, if you shake the bottle like crazy, suddenly you see a cloudy mixture form for just a couple of seconds before the oil and water quickly sort themselves and separate again.

In order to keep the oil suspended in the water, you need an emulsifier. Common emulsifiers include Emulsifying Wax, Cetearyl Glucoside and Cetearyl Alcohol, Glyceryl Stearate SE, and Cetyl Alcohol NF to name a few. There is quite a bit of science behind creating a stable emulsion, but sticking to the basics, in order to bind oil and water together to make any lotion, cream, or conditioner you need an emulsifier.

How Do Emulsifiers Work?

Emulsifying agents are soluble in both oil and water, accomplishing this by having one end of their molecule attracted to water (hydrophilic) and the other end attracted to fats/oils (lipophilic). When an emulsifier is added to an oil and water product, one end of the molecule dissolves in water and the other in oil. Thus these water and oil molecules are forced to be near each other without separating out the way a salad dressing might do when left sitting. This push and pull of the emulsifiers in the oil and water keeps the different substances suspended in a solution.

There are a variety of types of emulsifiers, and choosing the right one means finding a molecule with roughly equal attraction to water and oils in your particular formula. This means finding an emulsifier with either:

  • positive charge (cationic) – best used with low acidic or neutral mixtures (with a pH of 7 or lower)
  • negative charge (anionic) – best used with alkaline mixtures (with a pH of 8 or higher)
  • no charge (non-ionic) – typically used on their own or with a charged emulsifier to increase stability

There’s a lot to learn about choosing the ideal emulsifier for your product, so we encourage you to read the individual descriptions or our available emulsifiers or check out this blog for more in-depth information.

Solubilizers

When something is soluble it means it is able to be dissolved in water. For example, sugar is soluble in water. When you add sugar to water and stir, it quickly dissolves and you end up with a sweet glass of water. Solubilizers, as they relate to making cosmetics, help to make otherwise insoluble liquids soluble in water. For example, if you wanted to make a body spray with essential oils, you could simply add essential oils to your spray, but you would have to vigorously shake your spray before use. This is why we highlighted how Acacia Gum is a great solubilizer for this purpose in this easy Perfume Spray Video.

You need a solubilizer to help keep the essential oils and water together, but this is not quite the same as emulsion. We want the oil to be soluble in water, not just in a mix of oil and water at a more even ratio.

Enter solubilizers! In the example of a perfume spray, you would mix your essential oils with a solubilizer before adding to your spray. This would prevent you having to shake before each use. Examples of solubilizers include Polysorbates, Safflower Oleosomes, and Propanediol. (Side note: Not to be too confusing, but often an emulsifier can also be a solubilizer depending on how it’s used in each formula).

How Solubilizers Work

Solubilizers are similar to emulsifiers in that they have both hydrophilic and lipophilic traits, but solubilizers tend to be completely water soluble and only a little oil soluble. In practice this means they can suspend smaller amounts of oils (think essential oils in perfume or room sprays), and because they are solubilizing only small amounts of oil the entire solution can still appear clear or lightly hazy.

You should use solubilizers when adding just small amounts of oil to a water-based product. When scenting a toner, a spray, a gel, etc., these can be your best friend. It will depend on the specific solubilizer and essential oil you use to determine the ideal ratio of product to emulsifier.

 

Now that you know what emulsifiers and solubilizers do and some common examples, you can better understand the ingredients in your hair and skincare products. Let us know if you have questions about emulsifiers and solubilizers, or if you’d like us to define other terms you’ve seen used.

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