Reliable confirmation of a cosmetic product’s efficacy and safety requires a properly designed testing programme. Changing environmental conditions, new product development projects and the need to substantiate product claims with reliable evidence make appropriate test planning particularly important. In this article, we take a closer look at winter skincare efficacy testing, the importance of selecting the right study population and two key elements of microbiological safety assessment.
Find J.S. Hamilton on Skinobs
J.S. Hamilton is now available on Skinobs, an international platform connecting cosmetic brands with laboratories and research partners from around the world.
Our profile provides information about our testing capabilities and services for the cosmetics industry, including efficacy and safety testing, instrumental assessments and clinical studies conducted under specialist supervision.
Our presence on this international platform makes it easier for cosmetic brands to find a research partner and explore available laboratory capabilities when planning a project and selecting methods to substantiate specific product properties.
Meet J.S. Hamilton at COSMETIC 360 in Paris
On 14-15 October 2026, J.S. Hamilton representatives will be attending COSMETIC 360 in Paris, an international event dedicated to innovation in the cosmetics and fragrance industry.
The event provides an opportunity to exchange expertise and discuss current trends, technologies and challenges in cosmetic product development. It is also a valuable setting for conversations about efficacy testing, instrumental methods and approaches to substantiating cosmetic product claims.
COSMETIC 360 will take place at the Carrousel du Louvre in Paris. Schedule a meeting with members of our team by contacting us at cosm@jsh.com.pl to meet with them in person and discuss your planned research projects and potential opportunities for collaboration.
Winter Skin Testing – How Can the Efficacy of Winter Skincare Products Be Objectively Assessed?
Low temperatures, wind and dry air can negatively affect skin condition, leading to reduced hydration, increased transepidermal water loss (TEWL), greater roughness and impaired skin barrier function.
For cosmetic products intended for use during the winter season, it is therefore important to design studies in which the selected methods correspond to both the characteristics of the product and its intended claims.
Winter Skin Testing may include the assessment of:
- skin hydration using a Corneometer,
- skin barrier function through TEWL measurement,
- skin roughness and scaling,
- selected parameters related to skin colour and appearance.
An appropriately designed measurement panel provides objective data on product performance in areas particularly relevant to skin exposed to adverse environmental conditions.
The results can then be used to substantiate claims relating to hydration, support of the skin barrier function, or improvements in skin condition and appearance during the winter season – “For skin exposed to cold and dry conditions”.
Study Population Selection – Why Does It Matter for the Reliability of Results?
The reliability of an efficacy study depends not only on the measurement method used. The characteristics of the people participating in the study are equally important.
In human studies of cosmetic products, participants are selected according to criteria reflecting the characteristics of the product and its target group. Factors taken into account may include age, sex, skin characteristics and the presence of specific features targeted by the cosmetic product.
This approach streamlines the participant qualification process and helps establish a study population that corresponds as closely as possible to the product’s intended target group.
In clinical studies, the qualification process may include a detailed medical and dermatological interview as well as an assessment of skin condition by a dermatologist acting as the principal investigator. This allows the inclusion and exclusion criteria to be applied appropriately and helps limit factors that could affect the interpretation of study results.
Studies conducted under specialist supervision also enable more detailed characterisation of individual participants, documented in clinical observation records. Appropriate population selection is therefore one of the factors influencing the quality and usefulness of the data obtained.
Microbiological Quality and Challenge Testing – Two Different Elements of Safety Assessment
Assessing the microbiological safety of a cosmetic product requires consideration from more than one perspective. Microbiological quality testing and preservation efficacy testing answer different questions and should therefore not be treated as interchangeable methods.
What Does Microbiological Quality Testing Determine?
Microbiological quality testing assesses the microbiological status of a product at the time of analysis. It enables the determination of microbial counts and verification that the product does not contain specified microorganisms considered undesirable.
The results therefore provide information about the current microbiological quality of the cosmetic product.
What Does a Preservation Efficacy Test Assess?
A Preservation Efficacy Test (PET), also known as a Challenge Test, is used to assess the performance of the product’s preservative system.
During the test, specified test microorganisms are introduced into the product and their survival or reduction is subsequently monitored at defined time points. This makes it possible to verify whether the preservative system provides adequate protection in the event of potential microbiological contamination.
Microbiological quality testing and Challenge Testing therefore perform complementary functions. The former provides information about the microbiological quality of the product, while the latter assesses the effectiveness of its protection against microbial proliferation.
Plan Your Testing Programme Around Your Product and Its Intended Claims
The credibility of a cosmetic product is built at multiple stages – from ensuring microbiological safety and designing the study appropriately to selecting the right study population and using methods that objectively substantiate the product’s claimed performance.
A properly designed testing programme provides data that support product development and form the basis for reliable communication of its properties. It is particularly important to tailor the scope of testing to the formulation, target group, intended use and claims the manufacturer intends to communicate.
If you are planning cosmetic product testing and would like to select the scope of analyses according to the characteristics of your product and its intended claims, contact the J.S. Hamilton team using the form below.