How to hydrate gums in cosmetic formulas
When you are new to formulating, you may not be aware of just how useful properly hydrated gums and polymers are in cosmetic formulas, and how much should be used to get the desired results.
If you’re super new to formulating and not sure about how to start, enjoy our FREE Cosmetic Formulation Masterclass first, to get you used to formulating tips and terms. This masterclass will also help you gather essential equipment and get used to reading formulas and how to put products together.
One of the great things about the Create Cosmetic Formulas program is you don’t need to know how to properly hydrate gums or polymers to get the best results in your cosmetic formula! The program will guide you on which gums or polymers suit which cosmetic formulas, in which amounts, and how they should be processed to ensure they work well.
But just in case you wanted to know a little more about gums and polymers, and how they should be used, read on to find out…
If you are new to formulating, get started right with our FREE Cosmetic Formulation Fundamentals Masterclass – register and start straight away here.
Why are gums and polymers used in cosmetic formulas?
When properly processed (hydrated), gums and polymers are a great addition to cosmetic formulas to boost stability (shelf life), support the viscosity of a product, and can also be used to manipulate performance and texture.
However, if gums and polymers are used in the wrong type of cosmetic formula, the wrong amount or not processed (hydrated) properly, they may have no benefit at best, or at worst, cause balling and instability.
They may also be one of the main functional ingredients used to create certain product forms, such as in many types of serums – so correct selection and hydration in these cases becomes even more crucial!
How should gums and polymers be processed/hydrated?
To work as intended, gums and polymers must be hydrated properly in a formula. This is essentially the formation of hydrogen bonds with water, so that they swell to provide their intended benefits.
Different gums and polymers required different methods to hydrate properly. Some common examples include:
- xanthan gum: hydrates best when it is first slurried in humectant such as glycerin or propanediol, then added slowly to water whilst it is being stirred. Adding xanthan gum direct to water is prone to causing ‘fish eyes’: insoluble clumps of the gum that may never hydrate, and the sample or product is then ruined.
- hydroxyethyl cellulose: this is a partially synthetic modified cellulose material that is easier to use, with better gelling properties, than its totally natural counterpart. Hydroxyethyl cellulose needs to be added to a cosmetic formula and then stirred for a very long time, which can be impractical; or can be rapidly hydrated by alkalising the water (using an alkalising agent to raise the pH to about 8) whilst it is being stirred. The final pH can be adjusted back to a more suitable pH level (such as 5 or 6) once the gum has turned into a clear gel.
- guar hydroxypropyltrimonium chloride: this is another partially synthetic modified gum ideal for use in wash off formulas such as body wash, shampoo and conditioner, for a lovely, conditioned feeling. To hydrate this cosmetic ingredient, it should be added to a formula and the pH dropped using a suitable acidifying agent while the water is being stirred. Once a clearer gel forms, you can raise the pH back to 5 or 6 to suit the finished formula.
- carbomers and C10-30 alkyl acrylates (and similar): these synthetic gelling agents are able to form totally transparent ‘set’ gels in various cosmetic formulas for a range of skin or hair needs. They should be added to water and stirred using low shear (a propeller stirrer, not a blade stirrer or homogeniser) until they are dispersed, then a very small amount of alkalising agent should be added while stirring continues. Using these materials needs very careful addition of the neutralising agent: too little, and they won’t thicken properly; whilst too much will turn your cosmetic formula water thin. You will also usually need to be very careful about other ingredients in the cosmetic formula which may be incompatible with the polymer you have selected. In many cases, the final pH should not be adjusted once full viscosity and hydration has been achieved either.
How much gum or polymer should be used in a cosmetic formula?
The amount you use of each type of gum or polymer will depend on why it is being used in a cosmetic formula. For example:
- many grades of xanthan gum can feel a bit tacky and remain translucent (cloudy) in a formula, so are best used to support stability in creams and lotions where it isn’t ‘seen’. In these types of formulas, you would typically use 0.3 – 0.5%w/w. It can also be used in cloudy looking foaming formulas to help boost foam and make them more gel like; in these instances, it may be used from 0.5 – 1.0%w/w. More expensive and specialised grades can be used to build serum or gel formulas without a sticky skin feel, but these may be harder to source. Being natural, xanthan gum is a great addition to cosmetic formulas where you want to claim the use of natural and sustainable ingredients. It is anionic, meaning it is better suited to anionic or non-ionic formulas.
- hydroxyethyl cellulose is partially synthetic and will form non-tacky gels. Different grades are available from different cosmetic ingredient suppliers, so you may need to try a few different sources if you are trying to build a very specific type of viscosity. It is non-ionic so is highly compatible with most other cosmetic ingredients. It may be used from 0.3 – 1.0%w/w depending on the specific grade and purpose in a finished formula.
- guar hydroxypropyltrimonium chloride is also partially synthetic, and carries a cationic charge but is compatible with anionic surfactants. It is not usually used for its gelling properties beyond boosting stability; it is instead used for its lasting skin and hair feel. It too can come in varying grades from different suppliers, so you will usually need to review supplier information to use the right amount to suit your cosmetic formulation goals specific to the grade they supply. Typical inputs can also vary from 0.3 – 1.0%w/w.
- carbomers and polyacrylates are such effective gelling agents when hydrated in the right cosmetic formulas, that their input is much lower; typically 0.2 – 0.3%w/w. Just remember to be careful of their incompatibilities with other ingredients, the final pH of the cosmetic formula and the method used!
Of course, other inputs may be used for various reasons in certain cosmetic formulas – but you would need to undertake more advanced training to ensure correct input, usage and processing in those cases. Follow the inputs recommended by the Create Cosmetic Formulas program specific to the type of formula you are creating to get the best results – we’ve already taken selections into consideration for you!
What about other types of cosmetic gums and polymers?
This is only a small selection of some of the more commonly used gums and polymers in cosmetic formulas, with their best processing methods.
If you want to start selecting your own gums and polymers, try our workshop on how to select the right gums and polymers for your cosmetic formulas here. This workshop helps explain why you might choose certain gums or polymers over others, with examples that are commonly available from cosmetic ingredient small suppliers.
You can of course study more with us at the Institute of Personal Care Science. From beginner cosmetic science workshops through to advanced cosmetic science and full Cosmetic Chemist qualification training programs, we teach you every step of the way to help you achieve your cosmetic formulation goals. Contact us for more information or visit our website to review the various courses available – 100% online – so you can study cosmetic science at a time and place that suits you.
Happy formulating!
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