Cosmetic Thickeners and Natural Polymers add texture and help stabilize lotions and creams, and also create a wide variety of different gels. Although they all perform the same function in a lotion, cream, or gel, they each have unique properties and can change the look and feel of your final product.
Selecting the right one for your project can be a little overwhelming given the wide variety available. There are also many synthetic thickeners and polymers, but our focus at Essential is on green chemistry and sustainability so we’ve selected the most popular natural cosmetic thickeners to highlight. Hopefully it will help you select the best one for your needs.
A quick note on definitions: a polymer is essentially just a large grouping of smaller units that make up a substance. All gums are polymers. Their general use, as outlined above, is to either stabilize emulsions or create a gel, i.e. to thicken something like a mask so it stays on your face rather than dripping off. Additionally, they not only stabilize and thicken, but many natural polymers have excellent skin benefits, including things like Konjac Powder and Hyaluronic Acid (HA).
(NOTE: Check out our recipe for a Hyaluronic Acid Serum at the bottom of this post.)
Working with Thickeners and Natural Polymers
There are a few tricks that make working with natural polymers and thickeners much easier. For example, dispersing a gum in glycerin makes it much easier to mix into your product. In general, gums will not hydrate in glycerin, but they will disperse. This dispersion of the powder essentially eliminates the risk of forming “fish eyes”. Fish eyes is a term used to describe the formation of gooey round clumps that form when a gum hydrates unevenly. If you do not want glycerin in your product, you can add your thickener by slowly sprinkling it into your product while high shear mixing. This method requires patience and time, making it a little harder to scale up to very large batch sizes.
By far the most commonly used natural gum in cosmetics, this affordable and easy to use gum is derived from the fermentation of the plant bacteria Xanthomonas Campestris. This anionic polysaccharide will disperse in vegetable glycerin, but will not hydrate. Xanthan gum is widely used because it is compatible with most ingredients used in cosmetics and it’s readily available and versatile.
Xanthan gum will hydrate in hot or cold water and creates a hazy but neutral pH solution. This gum will create a gel that can tolerate the addition of a wide range of water-soluble active ingredients.
Xanthan is also highly synergistic with galactomannans like Konjac. When Xanthan is mixed with Konjac, the viscosity of the gel will increase dramatically. Xanthan is also resistant to heat and shearing, making the gels produced with Xanthan highly stable. This is especially beneficial if you are shipping your products in high heat or to locations that are hot and humid.
Hydroxyethylcellulose (HEC) is a nonionic natural polymer made from plant cellulose. It’s made by exposing purified cellulose to sodium hydroxide and then reacting the alkali-treated cellulose with ethylene oxide. The hydrogen atoms in pendant hydroxyl (—OH) groups are replaced with hydroxyethyl groups, leading to a water-soluble polymer. Like Xanthan gum, HEC will form a pH neutral gel at 1%, but unlike Xanthan, this gel will be clear and colorless. HEC is soluble in hot or cold water and can also be dispersed in glycerin. HEC is compatible with most other gums but works especially well with sodium alginate.
This anionic polysaccharide is collected from the sap of the acacia tree. Acacia gum is a naturally-occurring gum soluble in hot or cold water and gives a clear solution of neutral to acidic pH. This gum is not a thickener unless used in concentrations above 40%, and this viscosity is lost at elevated temperatures making it less desirable for most formulations.
Acacia gum will help solubilize oils into water without increasing viscosity. This makes acacia a good choice to help incorporate essential oils into low viscosity water-based products like toners and sprays. Acacia works best when used at a 3:1 or even 4:1 ratio of acacia to essential oil. It also pairs well with other gums to help stabilize formulations.
Konjac Powder is comprised of a high viscosity soluble fiber called glucomannan, which can expand to 100 times its volume in water making it an extremely effective humectant in cosmetics. Konjac is rich in protein, lipids, fatty acids, plus vitamins A, B, C, D, & E, and natural minerals such as copper, zinc and magnesium. Konjac forms a clear, colorless gel and when mixed with xanthan gum, viscosity increases dramatically.
Sclerotium Gum is non-ionic thickener made from a fermented fungus. This versatile gum has high thermal stability and can help to enhance the skin’s moisture barrier, preventing trans-epidermal water loss and helping to keep the skin moisturized. Sclerotium will form a gel at 0.8% and is stable in a wide range of temperatures, salt concentrations, and pH. It can also be used with a high amount of ethanol (up to 20%) and glycols (up to 25%).
Sclerotium gum is an excellent choice as a suspending agent, meaning that particles dispersed in a sclerotium gum gel will remain suspended without settling. Sclerotium gum is also a great choice when formulating with alpha-hydroxy acids.
Hyaluronic Acid (HLA) forms a pH neutral colorless and crystal clear gel. Hyaluronic acid and sodium hyaluronate are often used interchangeably, and they are essentially the same thing. Sodium hyaluronate is the salt of hyaluronic acid developed to reduce oxidation, whereas hyaluronic acid is just hyaluronic acid. Both exist naturally in the human body, however, hyaluronic acid is usually created by bio-fermentation in a lab rather than harvesting from rooster combs. Generally in skincare, when you see hyaluronic acid, it means sodium hyaluronate that was lab-created to be bioidentical to the hyaluronic acid found in nature.
Size Matters! 20,000 Daltons Vs. 2,000,000 Daltons
When it comes to hyaluronic acid, size does matter. Size in chemistry is measured in Daltons. A Dalton is a standard unit of measure that quantifies mass on an atomic or molecular scale (atomic mass). The lower the molecular weight, the smaller the size of the molecule.
This is particularly important when choosing which hyaluronic acid to use in a skincare formulation. Lower weight HLA will not form a gel, and it is suggested that the lower molecular weight can cause irritation. Higher weight HLA will form a viscous gel, is less likely to irritate the skin, and it’s more effective as a humectant. Check out our video on hyaluronic acid for a visible demonstration of the different weights and check out this simple recipe for creating your own hyaluronic acid serum.
Gum Thickeners in Hair Care and Skincare
BONUS: Hyaluronic Acid Facial Serum Recipe
Equipment You’ll Need
- Stove top safe pot or beaker
- Stick blender or high shear mixer
- Measuring cups/spoon or scale
DIFFICULTY LEVEL: Easy
Approximate yield: 1 Pound
Approximate cost per pound: $2.54
Suggested Packaging: 1 oz airless pump
Suggested retail price: $15 – $20
|Ingredient||Weight – (pounds)||Kitchen Measurements||Percentage by weight|
|Deionized Water||.9731||2 Cups||97.5|
|Hyaluronic Acid Powder||.0100||1Tbsp||1|
|Tetrasodium Glutamate Diacetate||.0050||1Tsp||0.5|
- Heat water to 120F – 130F
- Slowly sprinkle Hyaluronic Acid Powder into the water while mixing with your stick blender or high shear mixer.
- Add Phenoxyethanol and Tetrasodium Glutamate Diacetate to preserve.
- Use on clean face after toner/astringent. Let absorb into skin, then apply moisturizer.
Please note that this recipe has not been challenge tested for preservation efficacy. If you use this recipe for market sales, it is up to you to ensure the safety of the product.
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