The viscosity of surfactant solutions is normally dependent on the size of the surfactant micelles, concentration of surfactants, the type/ratio of the surfactant used, temperature, and the micelle charge density.
Most thickeners work by promoting the formation of rod-like micelles by reducing charge density or crosslinking micelles. The optimum choice depends on the specific needs of the formulation, which include clarity, PH, ingredients to suspend, and the types of surfactants/concentration used. Other considerations include cold processing, and natural or PEG-free claims.
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An efficient system will normally use <2% thickener to achieve a functional viscosity of 5-10K cps using a typical 12.5% alkyl sulfate/2.5% Cocamidopropyl Betaine surfactant system. When designing a thickening system, try to use multifunctional ingredients that can provide additional benefits to the formulation, and use combinations of ingredients that work by different mechanisms to improve efficiency. Potential benefits of different classes of thickeners include:
- Liquid, cold processing with minimal mixing.
- Good low and high temperature viscosity and stability.
- Good fragrance solubilization.
- Synergy with salt.
- Good formulation clarity.
- Help to increase foam/lather.
- Improved mildness.
- Suspend and stabilize particles.
Thickening Technologies for Surfactant Based Products
Salt thickens by reducing micelle charge density, helping to promote the conversion of spherical micelles to rod-shaped micelles. Historically, sodium chloride has been used. However, divalent salts like magnesium sulfate are more efficient if compatible in the formulation. Viscosity of salt-thickened formulations decreases with increasing temperature and will not stabilize suspended particles. Using too much salt (>2%) can also impact the clarity and cloud point of the formulation.
Polymers are typically aqueous acrylate dispersions that work by crosslinking micelles. Cellulosic ethers are also used.
Aqueous acrylate polymer dispersions are preferred due to their ease of use and synergy when combined with salt. They are also excellent at suspending particles in formulations. Some examples of polymeric thickeners include:
- Carbopol Aqua SF-2 (Acrylates Crosspolymer 4, 32% solids) by Lubrizol
- Rheomer 33 (Polyacrylate 33, 29% latex solids) by Solvay Novecare
- Eliclear 4U (Acrylates Copolymer) by Seppic
- Methocel 40-101 (Hydroxypropyl Methylcellulose) by Dow Chemical
Polar Emollients/Low HLB Surfactants
Ingredients with a low HLB value like Laureth-3, Cocamide MEA and other polar lipids work by promoting the formation of rod-like micelles. These micelles are flexible, branched structures, which may entangle and dramatically increase viscosity.
Examples of polar emollients/low HLB surfactants include:
- Comperlan CMEA (Cocamide MEA) by BASF
- Hest GC818:(Glyceryl Isostearate, Caprylic/Capric Glycerides) by Global Seven
- Stepan Mild-GCC (Glyceryl Caprylate/Caprate) by Stepan Chemical
Nonionic Ethoxylated Surfactants
Nonionic ethoxylated surfactants work by cross linking micelles. Surfactants with more than 1 hydrophobic tail are more efficient and can attach to multiple micelles, leading to an increase of viscosity.
Some examples of nonionic ethoxylated surfactants include:
- Ethox NEBS-2 (Decyltetradeceth-200 Behenate) by Ethox
- Genapol LT (PEG-150 Polyglyceryl-2 Tristearate, Laureth-3, Dipropylene Glycol) by Clariant
- Dermothix 100 (Disteareth 100 IPDI) by Alzo
Sometimes referred to as secondary surfactants, amphoteric surfactants promote the formation of rod-like micelles by reducing micelle charge density/repulsion. They also significantly improve mildness, boost foam/lather, and synergistically work with salts to build viscosity.
Some examples of amphoteric surfactants include:
- Tego Betain F KB 5 (Cocamidopropyl Betaine) by Evonik
- Mackam HPC-32L (Sodium Cocoamphoacetate) by Solvay Novecare
- Mackam LAB (Lauryl Betaine) by Solvay Novecare
- Amphosol CDB Special (Cetyl Betaine) by Stepan Chemical
- Macat LHS (Lauryl Hydroxysultaine) by Pilot Chemical
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21 Responses to “Thickening Surfactant Based Products”
Best concise presentation of options for thickening traditional surfactant-based personal cleansing products I’ve seen. Well done!
For example I have bought crothix in liquid for and in pebble form. I would love to be able to make a thickener in advance so I can add it to my formula.
Any suggestions or help in this matter?
thanks for your time,
Pleas what ratio Can I use to formulate Sodium stearate between Stearic acid and Sodium hydroxide in production of Stick Deodorant
I use the hydroxy ethyl cellulose(HEC) in the formulations as a viscosity.
I have some difficulties to dissolve the product in the mix and especially industrially.
Thanks for your help.
Head laboratory and R & D control
Pre-wet the material by dispersing it in a glycol prior to addition to the aqueous phase. This prevents agglomeration and drastically reduces time to full dispersion.
I am trying to thicken sulfate free surfactant systems. For example 50% of a decyl Glucoside (as supplied) and 50% water. What will be a good thickener for this?
There is a Crothix Liquid that you can use. There are also some newer variations, like Versathix, that you may want to try.
I have achieved satisfactory thickening and lather using 8% surfactant combo, .5% HPMC and 1% sodium chloride but formulation is quite cloudy. You have any idea how to correct this? Thanks already
I used decyl glucoside in clear shampoo. What will be good thickener for this according to you?
Thanks for the article, I found the information about divalent salts / magnesium sulphate as thickener very interesting, what surfactants are compatible / will thicken with divalent salts / magnesium sulphate?
Any body can give me recipe how i can thicken sodium chlorite?
Viscosity 8000 -10000 cps.
Please sir , what is the ratio of magnesium sulphate and sodium chloride In lasba base liquid detergent.
Please sir,give me information about how to make dishwashing liquid for good quality.
I am urgently looking for a certified organic surfactants for a skin cleanser (NSF certified), Can you help please?
You can search Prospector for organic surfactants, then filter to include only NSF certified. https://www.ulprospector.com/en/na/PersonalCare/EcoTech/18653/NSF/search?k=certified+organic+surfactant&st=31
Hope this helps!
Content Manager, Prospector Knowledge Center
I am formulating a two phase system of surfactant and oil.
How do I thicken the surfactant phase so that after mixing the product I can obtain two separate layers quickly.
I have used NaCl but it takes 24 hours to separate.
Very difficult to have rapid phase separation when you have high concentrations of surfactants. Increasing the water phase density using polyols and salt will help. Also use an oil phase that has the lowest possible density with the lowest possible surfactant concentration.
I have tried NaCl to thickening a 15%SLES & 85%Water solution but not succeeded. What min. quantity of SLES should be added to water for thickening with NaCl.
You need to include Cocamidopropyl betaine in the formulation. It will also help stabilize the foam and make the formulation milder.
we’re in need of a thickening agent to thicken dewatered food processing waste water so it can be hauled safely. Preferably one that we could leave in the bottom of a container while the waste water sludge is deposited.
Can you or one of you colleagues reach out to me?
Xanthan gum will work in this application.
Thanks for reading!