The type and quality of packaging used also affects the stability of the product, as it protects the cosmetic product from the external environment.
On the other hand, potential leaching of substances in the packaging into the product must be evaluated. For this reason, compatibility between the packaging and its contents must be investigated, in order to ensure that no quality problems are introduced by the type of packaging material used.
All cosmetic products should be subjected to the stability and compatibility test; there are no exceptions as for the preservative efficacy test. Stability and compatibility tests must be repeated every time there is a change in the formula, packaging or manufacturing process.