Thickeners in Surfactant Systems

Dear Valerie: I’ve noticed mixed advice when it comes to thickening glucoside-rich cleansers. Some formulators report poor results with HEC, others recommend HPMC, and some suggest avoiding cellulose thickeners altogether. Is HSP a better option for these systems, or are there situations where cellulose-based thickeners still perform well?

—Rich N. Thick

Dear Rich, 

The first solution to thickening a glucoside-rich cleanser is to go to your lab notebook, cross out any of the APG surfactants and change them to literally anything else. I’m just kidding! Loyal readers know I’m not a glucoside fan. Great cleansers, but I personally disdain the feel on skin or hair. I also find they can matte fine hair, even worse if it’s damaged. To each their own!

When an alkyl polyglucoside is a primary surfactant, your system will be nearly impossible to thicken to a reasonable degree without the help of polymers—be they gums, cellulosics, acrylates, ethoxylates, you get the idea. While you can toy with viscosity by combing lauryl glucoside, decyl glucoside and coco-glucoside together in different ratios, an ancillary thickener for the water phase is quite helpful.

I personally don’t like using hydroxyethylcellulose (HEC) in surfactant systems because—in my experience—you tend to get viscosity instability over time. While it’s non-ionic and wouldn’t hurt a fly, hydroxypropyl methylcellulose (HPMC) is a much better choice for clarity and stability.

In the February 2025 issue of my column, I provide the necessary tools to more easily incorporate HPMC into surfactant products. The phrase “more easily” is a bit misleading as there is nothing easy about HPMC. For that, I’m sorry. It’s also not a great option if the idea of practically boiling your water phase isn’t appealing or need a cold process solution.

That being said, if you can get it in, it’ll say in! Companies like Dow have so many grades of HPMC, you can just pick one that meets the viscosity profile you’re seeking.

Hydroxypropyl starch phosphate is an interesting choice, and it does work. Much like it thickens and adds “creaminess” to an emulsion, it does the same for a surfactant system. I smile a little, thinking about the enhanced creamy profile it lends. It’s also innocuous—simply toss the electrolyte tolerant powder in your batch with good dispersion and it can play nice!

Downsides? It’s not for every product. You will not only never get clarity in formulation, but the wet stage can also lean towards feeling unctuous, which may not be appropriate for the end use.

I see a lot of APGs with xanthan gum; a high use level is required, and not all xanthan gums will stabilize with the surfactant systems, causing separation. 

Of course, carbomers or highly ethoxylated thickeners are a good choice, but if you’re using only APGs you’re likely not going to want to use an acrylate-based system. I only perfunctorily recommend ethoxylated thickeners. They work but tend to leave a bloated hand feel in the cleanser and certain ones can stick to hair in a gummy fashion. I also tend to believe a sole APG-user is not interested in PEG-ylated materials… but who knows!

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Valerie George

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Valerie George is a cosmetic chemist, science communicator, educator, leader, and avid proponent of transparency in the beauty industry. She works on the latest research in hair color and hair care at her company, Simply Formulas, and is the co-host of The Beauty Brains podcast. You can find her on Instagram at @cosmetic_chemist or showcasing her favorite ingredients to small brands and home formulators at simply-ingredients.com