Generally, there are three different types of stability in cosmetics:
The ability of a product to resist the colonization of microorganisms which
may metabolize important parts of the product and lead to deterioration and
therefore unstable galenic properties by degradation processes or pH
e.g. Microorganisms metabolize certain components of a product and the
resulting waste products cause a severe odor.
The ability of a product to withstand a change in chemical processes that can
make the product unstable.
e.g. Oxygen reacts with oils, causing the product to go rancid.
The ability of a product to withstand a change through physical
e.g. Separation of the emulsion by gravity.
Mostly this is a process composed of the above-mentioned processes.
e.g. Microorganisms metabolize an important part of the emulsion or greatly
lower the pH value. This not only causes chemical changes, but also physical