The purpose of Stability Testing cosmetic products is to ensure that a new or modified product meets the intended physical, chemical and microbiological quality standards as well as functionality and aesthetics when stored under appropriate conditions. During the Stability test (3 months duration) various parameters are tested.
Microbiological tests: It is evaluated if the product is microbilogically stable
Physical / Chemical Test
These describe approaches to predicting how well cosmetics will resist common stresses such as temperature extremes and light. It’s determined whether to perform such specialized testing based on the vulnerabilities of the particular cosmetic product and its anticipated shipping, storage display and use conditions. Tests are performed at 4 0C, 37 0C, 45 0C during 3 months and at 5 circles (low-high temperatures).
Parameters evaluated are e.g. color, odor, pH value, viscosity, texture, specific gravity, and emulsion stability (signs of separation).
Packaging can directly affect finished product stability because of interactions which can occur between the product, the package, and the external environment. For example, product constituents may be absorbed into the container or may chemically react with the container. In addition, the container may not fully protect the product from the adverse effects of atmospheric oxygen and/or water vapor, or volatile product constituents (e.g. fragrances) may evaporate through the container.
Glass tests: Glass is the most inert material and does not react with a cosmetic product in any way. For this reason all testing should be done in glass and the actual packaging. In this way we can determine if the cause of product failure is the formula or the package.
Weight loss tests: To determine evaporation (water loss through the container wall or closure gaps) weight loss evaluation is one of the most important tests that must be conducted. The weight loss should not exceed 1% per month for the package to be considered acceptable.
Leaking tests: the packaged product is tested in various orientations (upright, inverted, on its side, etc.) to determine whether the packaging may leak (especially during transport).