| What is it? |
Optiphen™ is a broad spectrum preservative that works well to preserve products like lotions, creams, cleansers, and shampoo bars. Due to its phenoxyethanol content it is not natural, but is often considered ‘more’ natural than Liquid Germall™ Plus. Optiphen™ is approximately 55.6% phenoxyethanol and 44.4% caprylyl glycol (source). Optiphen™ is part of Ashland’s larger “Optiphen™” line, so when you’re looking at ingredients with “Optiphen™” in the name, always check the INCI so you know exactly what it is—Plus, 200, HD, GP, OD, BSP, BSB-W, etc. They’re all different! |
| INCI |
Phenoxyethanol (and) Caprylyl Glycol |
| Appearance |
Clear semi-viscous fluid |
| Usage rate |
0.75%–1.5% |
| Scent |
Nothing really noticeable, especially in a finished formulation. |
| Approximate Melting Point |
Liquid at room temperature. |
| Effective pH range |
4–8 |
| Solubility |
Optiphen™ has limited solubility in water as phenoxyethanol is about 0.5–2.67% water soluble (source), while caprylyl glycol is about 0.3% water soluble (source). Ashland lists its water solubility as 1.2g/100g water, aka 1.2% (source). Optiphen™ is fully soluble in ethanol, isopropanol (aka isopropyl alcohol/rubbing alcohol), ethylene glycol, propylene glycol, butylene glycol, and glycerin. Because of its limited water solubility, Optiphen™ isn’t a great choice for preserving really watery formulations like hydrous serums unless you include an adequate solvent or solubilizer. |
| Why do we use it in formulations? |
Optiphen™ preserves our formulations so they don’t grow mould and get all gross and icky. |
| Do you need it? |
No. It is a good preservative choice, but I tend to prefer Optiphen™ Plus and Euxyl® PE 9010. |
| Refined or unrefined? |
Optiphen™ only exists as a refined product. |
| Strengths |
Effective and versatile preservative with relatively high heat tolerance (up to 80°C [176°F]), making it a good choice for using in products that need a preservative but will be too solid to add one at typical cool down phase temperatures (~40°C and cooler). |
| Weaknesses |
Optiphen™ is not very water soluble and as such doesn’t work very well in watery products like hydrous serums unless the formulation includes a compatible solvent. As with all preservatives that contain phenoxyethanol, Optiphen™ can thin emulsions—though just how much thinning you’ll experience can vary a lot with the formulation. |
| Alternatives & Substitutions |
You’ll need another broad spectrum preservative. I use Liquid Germall™ Plus a lot; it is more water soluble than Optiphen™ but has a lower heat tolerance. Optiphen™ Plus (INCI: Phenoxyethanol, Caprylyl Glycol, Sorbic Acid) and Euxyl® PE 9010 (INCI: Phenoxyethanol, Ethylhexylglycerin) are good alternatives. Plain phenoxyethanol can also work, depending on the formulation. |
| How to Work with It |
Optiphen™ can be hot or cold processed as long as your heated phase doesn’t exceed 80°C (176°F). I usually include it in the cool down phase of emulsions. For the best performance, ensure formulations preserved with Optiphen™ have a pH between 4–6. If you want to use Optiphen™ in a watery formulation like a hyaluronic acid serum, pre-distribute it in a suitable solvent (glycerin, propylene glycol, and propanediol 1,3 are probably the easiest options) before adding the water. I’d try using 3–5x the amount (eg. 1.5% Optiphen™, 4.5–7.5% solvent) and see how that works. (This strategy was suggested to me by cosmetic chemist Valerie George from Simply Ingredients.) |
| Storage & Shelf Life |
Stored somewhere cool, dark, and dry, Optiphen™ should last two years. |
| Tips, Tricks, and Quirks |
There are quite a few INCI-identical preservatives out there, including:
You can’t assume these INCI-identical products will perform the same way as Optiphen™ as the balance of the two ingredients can vary. For example, TRIstat® PCG contains 53–58% phenoxyethanol and 42–47% caprylyl glycol, while TRIstat® PCG90 is 88–92% phenoxyethanol and 8–12% caprylyl glycol. |
| Recommended starter amount |
30g (1.06oz) |
| Where to Buy it |
Buy it from an online DIY ingredient supplier.
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Want to learn more about preservatives and compare them? Check out this chart!