June 2017

Microchem Laboratory conducts hundreds of accelerated physical stability studies on personal care products each year.

Customers often ask the lab to recommend an appropriate time and temperature for the study. Most often, companies are looking for stability out to one year. We commonly suggest 10 weeks at 45°C (113°F) for this purpose. In our experience, that duration and elevated temperature reasonably predicts product stability after 1 year on store shelves. The basis for these parameters lies in the Arrhenius equation, which describes a two-fold increase in chemical reaction rates with each increase of 10°C.

Room temperature (real-time) stability tests are another option for determining shelf life. These tests may be performed alone, but they take much longer, so they are often run in conjunction with accelerated stability testing. Samples held at refrigerated temperatures serve as useful controls for both real-time and accelerated stability testing.

Ultimately, parameters for stability testing should be chosen by individual cosmetic manufacturers, taking into account the tendencies of each formulation and the anticipated commercial storage and display environment. No matter what route a company chooses to take, Microchem Laboratory is here to help.