Moisturizing cosmetics efficacy testing (GB/T 35823-2018)

Moisturizing cosmetics efficacy testing (GB/T 35823-2018)

Moisturizing cosmetics efficacy testing (GB/T 35823-2018):Moisturizing is one of the most fundamental and core functional demands of cosmetics, but there are numerous claims in the market such as' 72 hour long-lasting moisturizing 'and' deep moisturizing '. How can consumers distinguish between truth and falsehood? GB/T 35823-2018 "Guidelines for Evaluation of Moisturizing Efficacy of Cosmetics" serves as the authoritative standard for moisturizing testing of cosmetics in China, and establishes a unified standard for the industry through scientific and quantitative methods. As a third-party testing organization certified by CMA/CNAS, Zhongke Testing has completed over 2000 batches of product testing based on this standard and provided compliance support to more than 150 enterprises.

Standard Core Testing Principles and Indicator System

GB/T 35823-2018 adopts a combination technology route of 'capacitance method+closed chamber method' to construct an evaluation system from two dimensions: skin moisture content and barrier function. The moisture content of the stratum corneum (Corneometer) ® The moisture content is reflected by measuring changes in skin capacitance values. The baseline value for the inner forearm of healthy adults is usually between 30-50 AU (Arbitrary Unit). High quality moisturizing products can increase to 60-80 AU after 2 hours of use, and the 8-hour attenuation rate should be ≤ 30%. Transdermal water loss (TEWL, Tewameter) ® The integrity of the barrier is evaluated by monitoring the rate of moisture evaporation on the skin surface, measured in g/m ²/h. The lower the value, the stronger the water locking ability. After using qualified products, the TEWL value should be reduced by ≥ 15% compared to the baseline.

The standard emphasizes the importance of dynamic monitoring and requires the recording of change curves before use, 1 hour, 4 hours, 8 hours, and 24 hours after use. The test data of a known ming product pai hyaluronic acid face cream shows that its instant hydration increased the moisture content by 42%, maintained a 28% increase in 8 hours, and the TEWL value decreased by 23%, significantly better than the industry average. The characteristic of 'rapid increase slow release' is a typical manifestation of high-quality moisturizing products.

Standardized testing procedures and environmental control

Seemingly simple skin testing actually requires strict environmental control and operational standards. GB/T 35823-2018 specifies that the testing environment should maintain a temperature of (21 ± 2) ℃ and a relative humidity of (50 ± 10)%, and the subjects should sit quietly in the environment for 30 minutes to adapt. The constant temperature and humidity chamber of Zhongke Testing is equipped with the German Testo temperature and humidity monitoring system, with an accuracy of ± 0.5 ℃/± 2% RH, ensuring that data is not affected by environmental fluctuations.

The screening of subjects is equally crucial: healthy adults aged 18-65 should be selected, excluding patients with skin diseases and those who have recently used hormone drugs. The effective sample size for each group should be ≥ 30 cases. The testing area is usually selected as the 5cm × 5cm area on the inner side of the forearm, and evenly applied at a dosage of (2 ± 0.1) mg/cm ². To avoid subjective bias, the standard requires a double-blind controlled design, where both subjects and evaluators are unaware of the location of the test area and blank control.

In terms of instruments, it is recommended to use the Corneometer from Germany's Courage+Khazaka company according to the standard ® CM825 (moisture test) and Tewameter ® TM300 (TEWL test), these two devices are also the main models of Zhongke Testing. The capacitance measurement range of CM825 is 0-150 AU, with a resolution of 0.1 AU, ensuring the capture of subtle changes; TM300 adopts an open measurement principle with a response time of less than 10 seconds, making it suitable for dynamic monitoring.

Data reliability assurance and compliance services

As a cosmetics registration and filing testing institution recognized by the National Medical Products Administration, Zhongke Testing strictly follows the three-level quality control system of 'methodological validation sample testing data review' for moisturizing efficacy testing. Methodological validation requires assessment of precision (RSD ≤ 5%), repeatability (within group difference<8%), and stability (drift within 2 hours<3%); Sample testing shall be conducted in parallel with two people, and key data shall be reviewed and signed by the technical leader; Before the report is issued, it needs to undergo compliance verification through the LIMS system to ensure compliance with the requirements of the "Cosmetic Efficacy Claim Evaluation Specification".

The ceramide face cream of a cutting-edge brand had a problem of 'excellent immediate effect but insufficient long-term effect' in the detection. The technical team found that its film forming sealing performance was poor by comparing the TEWL curves at different time points. Based on this data, the company optimized the proportion of plant sterols in the formula, and the 8-hour moisturizing rate increased to 65% during secondary testing, successfully passing the registration. This closed-loop service of 'detection feedback optimization' is precisely the core value of professional testing institutions.

Industry challenges and technological innovation

There are still two major challenges facing current moisturizing testing: one is the exploration of in vitro model alternatives, such as 3D skin models that can simulate the structure of the stratum corneum, but the differences with the human body still need to be verified; The second factor is the influence of individual differences. Studies have shown that the response of different skin types to the same product can vary by up to 20% -30%. For this purpose, Zhongke Testing has established a skin database containing over 1000 samples, which can customize testing plans based on the target audience of the product.

With the deepening implementation of the Regulations on the Supervision and Administration of Cosmetics, it has become inevitable for efficacy claims to shift from a 'filing system' to a 'scientific verification system'. Choosing testing services certified by GB/T 35823-2018 is not only a requirement for enterprise compliance, but also a cornerstone for winning consumer trust. Zhongke Testing will continue to upgrade its technological capabilities and provide the industry with a full chain solution from raw material screening to finished product evaluation, helping the high-quality development of China's cosmetics industry.