In Part 2 of Emulsifiers Explained, we discovered that not all emulsifiers are the same.
They can be classified in different ways, and while several ingredients may be involved in creating a stable formulation, they aren’t necessarily doing the same job.
So, how do you know what each one is actually doing?
Welcome to Part 3.
Primary Emulsifiers: Bringing Oil and Water Together
Let’s start with the main job.
A primary emulsifier helps create the emulsion and hold the oil and water phases together. Primary emulsifiers are also often used together with co-emulsifiers to support the overall emulsification system.
Examples include:
BTMS-25, particularly in haircare
You’ll find primary emulsifiers used in products such as creams, lotions, moisturisers and hair conditioners.
But the primary emulsifier doesn’t always work alone.
Co-Emulsifiers: The Supporting Role
A co-emulsifier works alongside the primary emulsifier.
Its role can include supporting stability, increasing viscosity and improving the texture and feel of the finished product.
Examples available from BrightPack include:
These ingredients can be found in products ranging from lotions and barrier creams to haircare products and other cosmetic creams.
The important distinction?
A co-emulsifier supports the emulsification system – it shouldn’t automatically be treated as a replacement for the primary emulsifier.
Understanding that difference can help you make much more informed ingredient choices when developing your formulation.
And Then There Are Solubilisers
What if you aren’t making a cream at all?
Perhaps you’re creating a body mist, toner or facial spray and want to incorporate a small amount of fragrance or essential oil into a water-based formulation.
That’s where a solubiliser comes in.
Solubilisers help disperse fragrance and essential oils into water and can be used when creating clear or lightweight water-based formulations.
Examples available from BrightPack include:
PEG-40 Hydrogenated Castor Oil
These are commonly used in products such as body mists, toners, perfume sprays and facial mists.
So while primary emulsifiers, co-emulsifiers and solubilisers may all come up when you're learning about emulsification, their functions are different.
But What Type of Emulsion Are You Making?
Now there’s another piece of the puzzle.
When oil and water are combined into an emulsion, they can be arranged in different ways.
Two important types are oil-in-water (O/W) and water-in-oil (W/O) emulsions.
Oil-in-Water (O/W)
In an oil-in-water emulsion, oil is dispersed within water, with water forming the continuous phase.
These emulsions are typically:
- Lightweight
- Non-greasy
- Fast absorbing
- Easier to wash off
They’re commonly found in products such as body lotions, face creams, moisturisers and hand creams.
Ceteareth-20 is an example of an emulsifier used in oil-in-water formulations, while ingredients such as Cetearyl Alcohol, Cetyl Alcohol and Stearic Acid can be used as supporting co-emulsifiers or structuring ingredients.
Water-in-Oil (W/O)
Now flip it around.
In a water-in-oil emulsion, water is dispersed within the oil, making the oil phase the continuous phase.
These formulations are generally associated with a richer, more protective feel and can offer greater water resistance and longer-lasting moisturisation.
They can be useful in products such as barrier and protection creams and heavier moisturisers.
The type of emulsion you want to create is therefore another important consideration when selecting your emulsification system.
It’s About the Whole System
This is one of the biggest lessons to take from Part 3:
Don’t look at an emulsifier as an ingredient working on its own.
Think about the entire formulation.
What are you making? What texture do you want? What role does each ingredient need to perform? Are you creating an O/W or W/O emulsion? Does your primary emulsifier need support from a co-emulsifier?
Once you start asking these questions, ingredient names begin to make a lot more sense.
At BrightPack, we want to help small businesses and start-up brands understand not only which raw materials are available, but also what those ingredients are actually doing in a formulation. That’s why this series has been developed with technical input from our in-house chemist.
The better you understand the job of each ingredient, the better equipped you are to make informed formulation decisions.
But there’s another decision formulators often face – and it can cause plenty of confusion.
Natural or synthetic?
Is one automatically better than the other?
Coming next: Emulsifiers Explained Part 4 - Natural or Synthetic - Which Should You Choose?
Next week, we’ll look beyond the labels and unpack what natural and synthetic emulsifiers can offer – and why choosing between them isn’t always as straightforward as it sounds.