Cosmetics & Toiletries has released a new Formulating Forum feature, "Exploring Natural Rheology Modifiers for Sustainable Cosmetic Systems," targeting one of the most persistent technical bottlenecks in green formulation: replacing synthetic viscosity-control polymers without losing performance.

The installment enters a category where rheology — a system's flow, viscosity and suspension behavior — has been anchored to synthetic benchmarks for decades. Carbomers, acrylate/C10-30 alkyl acrylate crosspolymers, acrylates/beheneth-25 methacrylate copolymers, and modified celluloses such as hydroxyethylcellulose give formulators predictable viscosity recovery, electrolyte tolerance and a defined skin feel. Plant-derived gums struggle to match those handles without reformulation work.

What pressure is driving the pivot

Three forces converge. First, retailer and brand natural-positioning standards — COSMOS, NATRUE, the USDA BioPreferred program and the EU Ecolabel for rinse-off and leave-on cosmetics — each define natural content differently, but all push suppliers to disclose origin, processing aids and derivation methods. Second, consumer-facing claims such as "microplastic-free," "biodegradable" and "naturally derived" sit above the rheology modifier as much as any other ingredient class. Third, regulatory momentum: the European Commission's restriction on synthetic polymer microparticles (microplastics) adopted under REACH applies to rinse-off cosmetics from 2023, with phased deadlines for leave-on and other categories scheduled through the decade, removing some legacy synthetic options in specific formats.

Where natural gums fall short — and where blends pick up the gap

Plant-derived options include xanthan gum (fermentation-derived from Xanthomonas campestris), sclerotium gum, gellan gum, carrageenan, locust bean, cassia, and cellulose derivatives including hydroxyethylcellulose and microcrystalline cellulose-carrier systems. Replacing a single carbomer typically requires a 2- to 4-fold increase in gum concentration and the addition of a co-thickener or synergistic salt. Shear-thinning behavior in xanthan-gellan blends can approximate synthetic systems, but salt sensitivity in xanthan-only networks remains a recurring failure point in sulfate-free surfactant formulations above 8–10% surfactant load.

For skin care emulsions, formulators should expect longer iteration cycles when pivoting to natural gums. Each rebuild requires re-running viscosity curves (Brookfield and cone-plate), yield-stress measurements, three-cycle freeze-thaw stability, and sensory panel work across at least two skin types. Hair care teams building sulfate-free systems face the steepest lift: matching carbomer-thickened cleansing viscosity with xanthan or sclerotium usually requires pairing with a cationic polymer or amphoteric surfactant to rebuild foam structure and conditioning deposition.

Procurement and compliance impact

INCI declarations and typical use concentrations (most natural gums sit in the 0.1–2.0% range) do not change dramatically. Supplier qualification work does. Sourcing teams now need certificates of origin, fermentation feedstock documentation for xanthan, gellan and sclerotium, and COSMOS or Ecocert letters for each grade. Price per kilo on natural gums remains 1.5–3× the equivalent carbomer, though contracts indexed to microbial fermentation capacity have eased that gap over 2024–2025.

What to watch next

Watch for the full text of the Natural Rheology Modifiers installment and the next Formulating Forum column in the same series, both housed in the C&T formulation library. Two practical data points will shape the next round of reformulation decisions: supplier-side disclosures on fermentation feedstock sustainability (corn, soy, sugar beet) and any updates to the REACH microplastics restriction phase-in timeline, which directly determines how long acrylate copolymer options stay on shelf for specific product types.