Have you ever wondered how oils in hair products stay so well combined with other ingredients in hair products? The key to this harmonious blend lies in emulsifiers!
Emulsifiers present in hair products serve as essential ingredients for creating emulsions. These chemical compounds possess the remarkable ability to separate oil into water and water into oils, earning them the title of emulsifying agents.1
Joining forces with my brilliant friend, a hair scientist and Cosmetic Formulator holding a PhD in Chemistry, we will dissect the fundamentals of emulsifiers. Together, we will navigate through the intricacies of their role in creating emulsions and explore the commonly used emulsifiers that significantly influence hair care formulations and manufacturing processes.
What are Emulsifiers for Hair Products?
Oil and water are two elements that simply will not mix – oil does not dissolve or disperse in water, nor does water dissolve or disperse in an oil medium. If you were to mix oil into water, even with vigorous shaking oil and water will never combine to create a homogeneous liquid- the two distinct liquids eventually separate.
Creating mayonnaise offers a practical illustration of this concept. When you beat egg yolks and drizzle in olive oil or coconut oil, you achieve mayonnaise. In scientific terms, egg yolks act as an emulsifier, serving as a bridge between substances that naturally resist blending.
How can we effectively blend the oil and water layers? We know that oil, less dense than water, floats on top while water, the denser fluid, remains at the bottom.
Water, universal and polar, allows only similarly polar compounds to dissolve. Blending non-polar oily liquids into the water can be a tricky task due to the higher surface tension of the oil and its tendency to resist mixing.
Surface tension is the amount of force/energy water molecules fight against breaking their surface barrier. To successfully disperse oil into the water and ensure they don’t separate and stay homogenous for a longer time, the surface tension of the water must be reduced.
Chemical compounds that can lower the surface tension of water are called surfactants or emulsifiers. By blending oil with a suitable emulsifier, you can create an even mixture referred to as an “emulsion.”2
Hair products rely heavily on emulsions, which deliver active ingredients to both the hair and scalp.
Conditioners, styling creams, waxes, and pomades are all unique examples of emulsified mixtures that combine oils with a water phase using multiple emulsifiers for maximum compatibility.3
Types of Emulsifiers in Hair Products
Anionic Emulsifiers
These are molecules containing a negative charge.
- Soaps
- Sodium stearate
- Potassium stearate
- Triethanolamine stearate
Cationic Emulsifiers
Most of the cationic hair-softening ingredients also act as emulsifiers.
- Cetrimonium chloride
- Stearalkonium chloride
- Behentrimonium chloride
- Cetrimonium methosulfate
- Behentrimonium methosulfate
Non-Ionic Emulsifiers
Due to their higher efficacy and low dosage usage needed to stabilize a product, they are often the most abundant and commonly used emulsifiers in hair and skin care products.
Some examples are:
- Polysorbate(s) – 20, 60, 65, & 80
- Ceteth 10, 20
- Cetareth – 10, 20, 25, 40
- PEG-(n) Hydrogenated castor oil [ n = 20, 30, 40, 60]
- PEG-100 stearate
- Glyceryl stearate
The number (n) in the above list denotes the degree of ethoxylation. It is the number of molecules of ethylene oxide per one molecule of emulsifier compound.
For example, Cetareth-10 means it contains 10 molecules of ethylene oxide. The higher the number of ethoxylation, the more hydrophilic (water-loving) a given emulsifier will be.
What are Co-Emulsifiers?
Co-emulsifiers are the chemical ingredients of a formulation, working in tandem with the main emulsifier to maximize product stability and improve aesthetics. They boost the emulsification process and make it simpler for products to be applied evenly on skin or hair.
These chemical ingredients enhance performance significantly and ensure that all aspects of a formulation come together in perfect harmony. Some examples are:
- Borax
- Cetyl alcohol (fatty alcohol)
- Stearyl alcohol (fatty alcohol)
- Cetearyl alcohol (fatty alcohol)
Making Emulsion: Emulsifiers in Action
An emulsion is a stable mixture of oils in water. In emulsion science, oil components of a formulation are called the “oil phase,” while water or water-soluble ingredients are called the “water phase.”
Emulsifiers can be added to either the oil or water phases, depending on their melting point and solubility. Both phases are mixed at an appropriate temperature (generally 70-80 for commonly used hair care formulations).
The mixing speed “rounds per minute” ranges from 1000 – 2000 rpm. The addition of emulsifiers reduces the surface tension of water and energy barrier, while high temperature and rapid agitation facilitate molecular interaction.
The emulsification process reduces the particle size of the oil phase. This process results in a white milky liquid, which gains viscosity during the cooling process.
The viscosity of the final emulsion product depends on a combination of formulation ingredients, choice of emulsifiers, and oils or waxes used in the oil phase.
Through emulsification, oil and water are effectively combined to maintain stability throughout the product’s shelf life.
Emulsifiers’ Role in Hair Products
The majority of hair care items are emulsions, such as conditioners, deep conditioning masks, treatments, styling creams, and pomades. Furthermore, hair coloring creams, color developers, hair relaxers, and perms also come as creams. They are all emulsions containing several oils, butter, or waxes emulsified in water using different emulsifiers.
The extensive selection of products demonstrates the critical significance of emulsions, emulsion making, and emulsifiers. Emulsions containing small oil droplets or butter make it easier to apply these lubricants on the hair or scalp, allowing for a uniform coating.
Combining oils into an emulsion makes their application and penetration into the hair fiber easier and more effective. This is precisely why many skin and hair care products utilize an emulsion as their delivery system.
FAQs
How can I effectively incorporate essential oils into water-based products using emulsifiers?
Emulsifiers are utilized to effectively incorporate essential oils into water-based products to create stable emulsions. Essential oils, being oil-based, naturally do not mix well with water. Emulsifiers facilitate the dispersion of essential oils in water-based formulations, ensuring stability and a balanced product. This process enhances the absorption of essential oils and their effectiveness in personal care products, hair care, etc.
What are the Best Natural Emulsifiers?
Several natural ingredients can act as emulsifiers in formulations. Here are some of the best natural emulsifiers commonly used in skincare and hair care products:
- Beeswax: Beeswax is a natural emulsifier that helps create stable emulsions. It also adds a thickening effect to formulations.
- Candelilla Wax: Derived from the leaves of the candelilla shrub, this wax is often used as a vegan alternative to beeswax.
- Lecithin: Typically derived from soy or sunflower, lecithin is a phospholipid that acts as a natural emulsifier. It’s commonly used in food and cosmetic formulations.
- Xanthan Gum: Produced through fermentation, xanthan gum is a polysaccharide that can stabilize and thicken emulsions.
- Gum Arabic: Obtained from the sap of the Acacia tree, gum arabic is a natural gum that can serve as an emulsifier.
- Vegetable Glycerin: While not a traditional emulsifier, vegetable glycerin can aid in the stabilization of emulsions and is often used in natural formulations.
- Borax: Borax is a mineral that can act as a co-emulsifier in combination with other emulsifying agents.
- Acacia Gum: Also known as gum arabic, acacia gum is a plant-derived substance that can contribute to emulsion stability.
Can You Substitute One Emulsifier for Another?
Yes! However, it comes with certain conditions. Changing an emulsifier and replacing it with a substitute depends upon the nature of the oils used in the emulsion and their polarity level.
It also depends upon the desired results of the end product, i.e. its viscosity, texture, and aesthetic feel.
For non-ionic emulsifiers, a table of hydrophilic-lipophilic balance (HLB) is available and frequently used by formulators to find a substitute.
Do Emulsifiers Dry Out the Hair?
Not necessarily! Most of the emulsifiers used today are gentle, mild, and skin-friendly.
Recent advancements in emulsion science have developed novel, high-performance, and multi-functional emulsifiers that not only manufacture emulsions but also provide emollience, and hair conditioning, and moisturization.
Some examples are:
- Glycereth – 7
- Glycereth-26
Both are ethoxylated glycerin, offering exceptional sensorial benefits to creams.
- Cetearyl Olivate
- Sorbitan Olivate
Both are olive oil-derived emulsifiers.
Summary
Emulsifiers play a significant role in emulsion-based hair care and skincare products, as well as various cosmetic products. They are the ideal ingredients for dispersing oil in water and vice versa.
Not only do they stabilize products, but also provide a unique texture and aesthetic features and aid in the delivery of active ingredients.
All types of hair creams, hair conditioners, or styling waxes, even body butter, etc., rely on suitable emulsifiers to come to life as perfect emulsions!
References
1. Silva, L.; Tonkovich Anna, L.; Lochhead Robert, Y.; Qiu, D.; Pagnatto, K.; Neagle, P.; Perry, S.; Lerou, J., Advanced Emulsions: Enabling Advanced Emulsion with Microchannel Architecture. In Cosmetic Nanotechnology, American Chemical Society: 2007; Vol. 961, pp 83-96.
2. Sjoblom, J., Emulsions and Emulsion Stability: Surfactant Science Series/61. CRC Press: 2005.
3. Kozlowski, A. C., Formulating Strategies in Cosmetic Science. Allured books: 2009.
