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Stability Testing/ Pao Testing
Stability testing is a test to evaluate the durability, effectiveness and safety of cosmetic products. These tests are important to ensure that the product remains stable throughout its shelf life.

Cosmetic products may be exposed to various chemical, physical and microbiological changes under storage conditions (factors such as light, temperature, humidity) and during use. Therefore, stability tests are systematic studies performed to determine the physical properties, chemical components, microbiological integrity and effectiveness of the product.

Stability tests can generally evaluate the following factors:
  1. Physical changes: Changes in physical properties such as odor, color and consistency are examined.
  2. Chemical changes: Chemical changes such as pH value of the formulation, decomposition or oxidation of active ingredients are observed.
  3. Microbiological integrity: Microbiological tests are performed to ensure that the product does not create a suitable environment for the growth of microorganisms.
  4. Label declarations: The accuracy of the features, usage instructions and expiration dates stated on the product label is checked.

Stability tests carried out in our laboratory allow you to guarantee the quality, effectiveness and safety of your cosmetic products. We strive to meet the requirements of your products by providing our customers with services in accordance with the latest technology and standards.

PAO (Period After Opening) Test – Usage Period Analysis After Opening
The PAO test is a scientific evaluation process to determine how long cosmetic products remain safe and stable after opening the packaging. This test is influenced by many factors such as the effectiveness of the preservative system in the product formulation, packaging material, storage conditions and user habits.
The lid of the product is opened in a simulation conducted in a laboratory environment, thus simulating consumer use. During the test period, the product is stored under the storage conditions specified on the label. The product is analyzed again in periods such as day 0, week 1, month 1,  month 2, month 3, month 6. The main parameters controlled are: 
 
  • Odor and color changes
  • Appearance stability
  • Chemical properties such as pH and density
  • Microbiological load and contamination control
The PAO period is usually indicated by the open lid symbol on the packaging. The expressions such as "6M" and "12M" next to this symbol indicate how many months the product can be used safely after opening. However, it should be noted that the PAO date and the expiration date are different: PAO represents the life of the opened product; expiration date represents the stability period of the unopened product.

PAO testing is an important part of the cosmetic product development process in terms of both ensuring legal compliance and providing safe usage information to the consumer.

If you would like to get more detailed information about your stability and Pao tests, you can contact our cosmetic analysis laboratory.
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