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. 

Get in touch with us for more info, samples or support