Sunscreen “Milk” - Stability
I am working on a sunscreen fluid (SPF 30) with ZnO as the only active - 17.5%
The viscosity is low, 300-500cps and it is meant to be packaged with a shaker ball in a tottle.
After 9 weeks at 45C we see phase separation that is easily brought back to homogeneous with less than 5 shakes.
My question is for anyone who has formulated these low viscosity sunscreens, would this be considered a failure? Even though it is meant to be “shake well before use”. I would love to hear some perspective/opinions.