Choosing the right ReadyMix™ Iron Oxide base for W/O sunscreen with esters and hydrocarbons
คำถาม
I am developing a W/O (Water in Oil) sunscreen formulation with the following oil phase and active ingredients:
- Oil Phase:
Coco-Caprylate/Caprate,Hydrogenated Polydecene,Squalane,Isododecane. - UV Filters (dissolved with heat):
DHHB (Diethylamino Hydroxybenzoyl Hexyl Benzoate),Ethylhexyl Triazone. - Powders/Dispersants:
Zinc oxide,Titanium dioxide,Polyhydroxystearic Acid.
Which type of ReadyMix™ Iron Oxides Yellow should I use between the Polyglyceryl-2 Triisostearate Based and the Cyclopentasiloxane Based version? Please provide the technical reasoning for the recommendation regarding compatibility and stability.
คำตอบ
For your W/O (Water in Oil) sunscreen formula, which consists primarily of esters (Coco-Caprylate/Caprate) and hydrocarbons (Hydrogenated Polydecene, Squalane, Isododecane), the recommended choice is:
Recommended Choice
ReadyMix™ Iron Oxides Yellow (Polyglyceryl-2 Triisostearate Based)
Reasons for Selection
- Superior Compatibility: Your oil phase is composed of esters and hydrocarbons. Polyglyceryl-2 Triisostearate is a high-performance ester that is perfectly compatible with Coco-Caprylate/Caprate and Squalane. It will integrate seamlessly into the continuous phase of your W/O emulsion.
- Enhanced Pigment Dispersion: This version uses pigments treated with Isopropyl Titanium Triisostearate (ITT). ITT-treated pigments are specifically designed for oil-based systems, providing excellent wetting properties, which results in a smoother application and better color development compared to silicone-based dispersions in a non-silicone oil phase.
- Formula Stability: In a W/O system, the stability depends heavily on the compatibility of all ingredients in the external (oil) phase. Using an ester-based colorant in an ester/oil-heavy formula reduces the risk of phase separation or pigment agglomeration.
- Avoidance of Volatiles: The Cyclopentasiloxane Based version contains volatile silicone (D5). Since your formula requires heat to dissolve DHHB and Ethylhexyl Triazone, using a non-volatile ester base is safer and more stable, as you don't have to worry about the base evaporating during processing or affecting the final viscosity.
- Skin Feel and Adhesion: Polyglyceryl-2 Triisostearate provides good skin adhesion and a creamy feel, which complements the emollient nature of Squalane and Hydrogenated Polydecene in your sunscreen.
Suggestion for Color Adjustment
To achieve the desired skin tone (Beige/Nude), you will also need the Red and Black oxides in the same base to ensure consistent stability and performance:
- ReadyMix™ Iron Oxides Red (Polyglyceryl-2 Triisostearate Based)
- ReadyMix™ Iron Oxides Black (Polyglyceryl-2 Triisostearate Based)
Mixing Tip: Since you are using Polyhydroxystearic Acid as a dispersant for Zinc Oxide and Titanium Dioxide, the Polyglyceryl-2 Triisostearate based colors will work synergistically with it to ensure all powders and pigments are perfectly distributed throughout the formula.
