Quick verdict
| Use case | Pick |
|---|---|
| ECOcert / Cosmos certified formula | Geogard ECT (Phenoxyethanol disqualifies) |
| Mainstream paraben-free positioning | Phenoxyethanol (cheaper, established) |
| Very acidic formula (pH 3-4) | Geogard ECT |
| Higher-pH formula (pH 6.5-8) | Phenoxyethanol (broader pH range) |
| First-time formulator | Phenoxyethanol (more forgiving) |
| Customer base avoiding phenoxyethanol | Geogard ECT |
| Strict natural-skincare label | Geogard ECT |
Why both exist
- Phenoxyethanol — INCI: Phenoxyethanol. A synthetic glycol ether. Single-ingredient broad-spectrum preservative. Effective pH 3-10. Industry standard for decades. NOT ECOcert/Cosmos approved.
- Geogard ECT — INCI: Benzyl Alcohol (and) Salicylic Acid (and) Glycerin (and) Sorbic Acid. ECOcert and Cosmos certified natural-positioned preservative blend. Effective pH 3-6 (best below 5.5).
When Phenoxyethanol wins
- Mainstream paraben-free products — well-established consumer acceptance.
- High-pH formulas — works up to pH 9-10 (Geogard fails above 6.5).
- Cost — single ingredient is cheaper than blended systems.
- Wide compatibility — fewer surprises when combining with other actives.
- Strong against bacteria — primary mechanism.
When Geogard ECT wins
- ECOcert/Cosmos certified formulas — required if you want natural certification.
- Natural-positioned label — appeals to clean-beauty customer base.
- “Phenoxyethanol-free” product line — caters to customers who actively avoid it.
- Synergistic — multi-component blend covers a wider organism spectrum.
- Strong against mould and yeast — salicylic + sorbic combo.
pH constraints — the biggest difference
Geogard ECT loses efficacy above pH 6.5. The salicylic acid and sorbic acid components both need to stay in their non-ionised form (low pH) for antimicrobial activity. Above pH 7, they’re essentially inactive — your formula will look preserved in the bottle and then grow mould within weeks.
Phenoxyethanol works pH 3-10. Much more forgiving of formula pH drift.
Concentration limits
- Phenoxyethanol in finished cosmetic: 1% maximum (EU and many other jurisdictions). When using a phenoxyethanol blend (e.g. Plantaserve P at 75% phenoxyethanol), maximum total blend in finished product is ~1.2% to stay within the phenoxyethanol limit.
- Geogard ECT in finished cosmetic: 0.6-1.2% recommended. No hard regulatory limit on the blend, but salicylic acid component carries its own limits.
Pregnancy considerations
- Phenoxyethanol: generally considered safe in pregnancy at cosmetic concentrations. Some conservative product lines still flag it.
- Geogard ECT: salicylic acid component may be flagged for pregnancy in some jurisdictions (though at preservative-system concentrations, well below salicylic-acid-as-active limits). For pregnancy-marketed products, consider Spectrastat G instead.
Sensitisation rates
- Phenoxyethanol: small (~0.5-1%) sensitisation rate, mostly in compromised skin.
- Geogard ECT: ~1-2% sensitisation rate (driven by salicylic acid component).
Substitutes for both
For “broad-spectrum at pH 4-6” use cases:
- Plantaserve E — Geogard 221 equivalent, similar to Geogard ECT.
- Optiphen / Optiphen Plus — phenoxyethanol + caprylyl glycol blends.
- Liquid Germall Plus — broader spectrum than either, formaldehyde-releasing chemistry.
- Euxyl K 903 — natural-positioned broad-spectrum.
- Spectrastat G — caprylhydroxamic-acid based, alternative pH range, pregnancy-friendlier.
For natural certified:
- Geogard 221 / Plantaserve E — closely related.
- Naticide — natural-positioned, gentler spectrum.
- Leucidal Liquid — natural ferment, weakest preservative — usually paired with another.
→ Full ingredient page: Phenoxyethanol · Geogard ECT