Preservation & Stability: Clean Systems That Hold Up in the Real World
If there’s one part of a formula that’s both misunderstood and under-prioritized, it’s the preservation system. Everyone wants a product that’s “clean, minimal, and low-tox”—until they experience mold at fill, separation after shipping, or a microbial failure two weeks into shelf life.
As a formulator with over 20 years of hands-on experience, I’ve seen the full evolution of preservation trends—from paraben panic to plant-derived multifunctionals. But one truth remains constant: there is no clean label without safety and shelf stability. Below is a guide to designing preservation systems that align with brand values and regulatory realities—while holding up under the pressures of manufacturing, packaging, climate, and consumer use.
Step 1: Preservation Is Not a Plug-In—It’s a System
A preservative is not just a single line on your INCI deck—it’s a multi-layered strategy. Effective preservation is built into the formula from day one, not added at the end like a stabilizer.
Here’s what we consider upfront:
Water activity: Low water ≠ no preservation. Even balms and powders can mold from condensation or humid bathrooms.
pH environment: Some preservatives are only active in acidic systems (e.g., sorbates, benzoates), while others degrade outside a narrow range.
Emulsion type: Oil-in-water emulsions require very different strategies than waterless systems or bi-phase mists.
Packaging interaction: A jar will always require a more robust preservation approach than an airless pump.
Failing to design a system around the packaging format is one of the top causes of early microbial growth in clean-label products.
Step 2: Match Preservation Strategy to Brand Positioning
Whether you’re formulating for a “certified clean” brand, a dermatologist-backed clinical line, or an herbal wellness range, your preservation strategy has to align with the claims and customer perception.
Here are examples of common brand values and compatible systems:
Brand Value
Recommended Preservation Approach
“No synthetic anything”
Fermented, nature-derived, essential oil-based hurdle systems
“Low-tox/clean science”
Organic acids + multifunctionals + weak phenoxyethanol systems
“Sensitive skin”
Chelators + low-dose broad-spectrum blends
“EU/Global compliance”
Benzoic/sorbic acid systems or organic acid + polyol blends
Remember: Preservative-free is not a claim—it's a liability. Instead, reframe your strategy as "minimal but functional preservation" or "multifunctional defense systems."
Step 3: Think in Hurdles, Not Hero Ingredients
No single preservative will protect your formula in every condition. That’s why we build hurdle systems—layered approaches that reduce the microbial load and create inhospitable conditions for contamination.
Key hurdles include:
Preservatives: Phenoxyethanol, ethylhexylglycerin, sodium benzoate, potassium sorbate, caprylyl glycol, etc.
pH management: Keeping pH < 5 for acid-dependent systems
Chelators: Sodium phytate, sodium gluconate, or EDTA (if allowable) to limit metal-catalyzed microbial growth
Water activity control: Humectants like glycerin or polyols that bind water
Packaging choice: Airless pumps, one-way dispensers, or powder-to-foam systems
Pro tip: Combining a weak acid preservative with a glycol or glycerin-based humectant can create a more stable, globally accepted system while maintaining clean label integrity.
Step 4: Stability Testing for the Real World
Too often, I see “stability” tested in a 20°C closet—while the product is meant to ship across three continents and sit in a hot bathroom. That’s not good enough.
A real-world preservation and stability plan includes:
Temperature cycling (4°C ↔ 40°C over 2–4 weeks)
Freeze/thaw testing for water-heavy or natural emulsions
Light exposure testing (especially for tinted products, actives, and botanicals)
Package compatibility testing (Does the preservative leach? Will the EO degrade the pump seal?)
PET/Micro Testing (at least 28-day challenge test on the final formula, not just the base)
Shelf stability = packaging + preservation + process. If one of those elements is weak, the system fails—regardless of how “clean” your ingredients are.
Common Clean Beauty Failures—and How to Fix Them
Here are a few real-world preservation mistakes I’ve seen in clean label launches—and the fixes that saved the product:
Issue: Mold in jars within 2 weeks of opening
Fix: Switch to airless pump, lower pH to 4.8, add sodium benzoate + potassium sorbate combo with caprylyl glycolIssue: Clear toner turns cloudy after a few days in heat
Fix: Drop glycerin from 6% to 3%, add sodium phytate, swap preservative to an ethanol-free glycol + levulinate systemIssue: Mask separating in winter storage
Fix: Add lightweight co-emulsifier with antifreeze properties, run extended cold-cycle testing before launchIssue: Incompatibility with packaging seals
Fix: Replace essential oil blend with encapsulated version; retest PET in final packaging
Final Thoughts: Clean Preservation Is Science, Not Marketing
The most elegant formulas aren’t the ones that avoid “no-no lists.” They’re the ones that perform under pressure, travel well, and stay safe for the consumer from first use to last pump.
A modern preservation system should:
Align with your brand ethos
Meet global regulatory standards
Scale with your CM without excessive revalidation
Hold up under unpredictable consumer handling
After 20 years of working with brands and manufacturers, here’s what I’ve learned:
A formula isn’t finished when it smells nice and feels good. It’s finished when it can survive the real world.
Victoria Vohland
Founder & Head of Product Development