Recent in Testing (page 10 of 21)

Analyzing Deposition from Rinse-off Hair Products

The most common approach to determine ingredient deposition on hair is to analyze the treated tresses, but this poses several challenges. Instead, the authors describe a novel approach based on determining the amount of ingredient collected in the rinse water, and back-calculating the amount deposited on hair. Development and validation efforts discussed here use polydimethylsiloxane as a model compound.

Method to Reproduce In vitro Cosmetic Product Photostability Findings

The present article describes a reproducible method for determining the photostability of sunscreen products. This method is based in part on the in vitro determination of the UVA protection factor as proposed by Colipa for the irradiation aspect, and on the spectroscopy of a sunscreen in dilute solution for the absorbance measurement aspect.

The Effect of Glycerol on the Water-holding Capacity of Chemically Irritated Skin*

Glycerol is one humectant commonly employed due to its high hygroscopic and hyperosmotic properties. It is used in cosmetics as a moisturizer and in pharmaceutical formulations as an active compound. Being naturally present in the skin, glycerol was quickly identified for its role in skin hydration, similar to natural moisturizing factors (NMF).

Octocrylene Concerns Flag Industry's Attention

The industry reacts to a new study published in Contact Dermatitis reviews reports of the UV absorber octocrylene for its potential to cause photo contact allergy.

Correlating Aging with Skin’s Mechanical and Optical Properties

The aim of this study was to monitor the evolution of biomechanical and optical properties of the skin with aging. Different biophysical parameters were measured, including skin: elasticity and firmness, color, brightness, fluorescence emission, sebum content, hydration and pH. A significant evolution of the evaluated parameters with aging was observed.

Proposed Method to Evaluate the Microbiological Stability of Cosmetics During Use

The authors propose an approach to assess the microbial stability of a product during use, referred to as the Microbiological Use Test (MUT), and apply this analysis in case studies to predict the microbiological risk of commercial products. The described test has been used successfully in the development of cosmetics.

Sandblasting to Improve the Reproducibility of In vitro Sunscreen Evaluation

SPF test results from substrates treated using a traditional sandblasting technique are compared with those from substrates treated using a new process. Based on the topographic control of 10 batches and 34 sunscreen evaluations, the authors concluded the new process had better topographic reproducibility, consequently improving the SPF repeatability and reproducibility in vitro.

Collagens I and III, and Elastin Activation for Anti-aging

As an alternative to semi-invasive facial rejuvenation techniques, the authors developed an active ingredient to reactivate senescent fibroblasts by stimulating metabolic pathways for collagens I and III, and elastin. The biological activity of the resulting ingredient is investigated here using in vitro models, ex vivo explants and human volunteers.

Measuring the Water Content of Hair

Consumers have demonstrated a clear desire for hair that isn’t “dried out” while also demonstrating a clear distaste for the effects of high humidity on hair. To find the balance in creating products, it is necessary to have an accurate means of measuring hair’s water content. This article describes equipment used to perform this task while highlighting experimental variables that can produce suspect results and lead to incorrect conclusions.

State of São Paulo in Brazil Bans Cosmetic Testing on Animals

This ban in the Brazilian state follows a ban from India, Israel and the European Union, as well as debate and potential regulation changes in countries like China.

‘Anti-imperfection’ Claims

Four tests can be undertaken to substantiate the claims covered in this article. Colorimetry analyzes pre- and post-product application skin tone. A Cutometer or dermal torque meter measures the rate of skin extension pre- and post-product treatment, and stratum corneum turnover tests and acute profilometry studies show the rate at which skin is renewed or changes in the evenness of skin occur.

Measuring Hair Strength, Part II: Fiber Breakage

In the mechanical testing world, the tendency for materials to fail under a repeated stimulus is termed fatigue testing, and this article discusses this topic in relation to hair breakage. It will be shown that this alternative testing approach provides considerable insight into the cause of hair breakage, and subsequently allows for the identification of strategies for its minimization; it will also be demonstrated how learning this provides the underlying theory by which anti-breakage and even “strengthening” claims are crafted.

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