Formulating tips for Eclipse Z zinc oxides
Formulating uncoated or TECS-coated Eclipse Z
Three key formulating principles to get the best performance out of uncoated and TECS-coated Eclipse Z products
1. use a dedicated dispersion aid
Ensures stability of Eclipse , avoids agglomeration and keeps it well-dispersed in the oil phase
Helps to avoid interaction between ZnO and emulsifiers to ensure maximum emulsion stability and (sunscreen) performance.
Polyhydroxystearic Acid is a recommended dispersing aid
2. optimum amount of dispersing aid
Using the right amount of dispersing aid is key. An optimum amount ensures stabilisation of Eclipse and the emulsion.
Concentration ladder study
Create dispersions with 30-50% concentration of Eclipse with varying levels of dispersing aid.
Measure viscosity of such dispersions to create the ladder study and determine the optimum amount of dispersing aid.
50% dispersion of Eclipse Z1 in CCT, using varying concentrations of Dispersun DSP-OL100 (PHSA). Optimum level: 3% PHSA - relative to Eclipse Z1. This means: when using 20% Eclipse Z1 in a formula, 3% of 20% = 0.6% in formula needed.
3. building up the formulation and order of addition
A step-by-step build up ensures Eclipse ZnO is fully covered by dispersing aid and avoids the interactions between zinc oxide and other ingredients of the formula. These 5 steps will contribute to overall formula stability and (sunscreen) performance.
1. Combine ester and dispersing aid and no other ingredients
2. Add Eclipse ZnO, small doses at a time while mixing
3. Disperse Eclipse ZnO under high shear mixing
4. Add other oil phase ingredients
5. Combine oil and water phase to prepare final product
Additional formulating tips
Adding Eclipse to the oil phase
Do not add all of the Eclipse ZnO to the oil phase at once. Add in small doses and wait until absorbed before adding the next.
Making O/W emulsions
Add the hot (80-85˚C) oil phase, gradually, to the cold (40-50˚C) water phase to avoid phase inversion.
When using Xanthan gum as O/W thickener
Add xanthan gum post-emulsion to avoid formulation/emulsion inconsistencies and performance degradation.