A consumer cross-over trial suggests that there are significant seasonal changes of the tensile properties (wet) of human hair

© 2023 The Authors. International Journal of Cosmetic Science published by John Wiley & Sons Ltd on behalf of Society of Cosmetic Scientists and Societe Francaise de Cosmetologie..

OBJECTIVES: Through the cooperation with an industrial partner, we gained a set of data for the tensile properties (wet) of human hair. The hair samples originated from a cross-over study with two groups of individuals, using for a topical application sequentially two products (A and B). Each phase of the study lasted 6 months. The phases of the study by chance covered first largely the winter and then the summer period. Initially, tensile variables were chosen, which not only reflect the mechanical properties of hair (modulus, break strain, and break stress) but which are also considered to have a good connection to practice-relevant hair properties. The initial analysis of the data showed that changes were observed for the variables due to the treatment phases. However, these were either small or difficult to interpret.

METHODS: Against this background and using two-factor analysis of variance, we investigated the hypothesis that the tensile properties of hair (wet) may show significant seasonal changes. For this, we chose those two independent variables, which reflect the properties of the intermediate filaments (modulus) and the matrix (break strain) in the composite structure of the hair cortex.

RESULTS: The results support the 'seasonal' hypothesis and clearly show that the variables show significant changes from Winter to Summer (modulus: 10% increase; break strain: 3% decrease). The seasonal effect was thus a major reason, why the first stage of the analysis of the data was inconclusive.

CONCLUSIONS: The tensile properties of the main morphological components of the cortex show distinct seasonal changes. Towards the summer, the hair becomes stiffer and more brittle. Furthermore, the results suggest that seasonal effects may need to be taken into account when conducting studies on lengths of hair grown during different seasons.

Medienart:

E-Artikel

Erscheinungsjahr:

2024

Erschienen:

2024

Enthalten in:

Zur Gesamtaufnahme - volume:46

Enthalten in:

International journal of cosmetic science - 46(2024), 2 vom: 30. Apr., Seite 153-161

Sprache:

Englisch

Beteiligte Personen:

Wortmann, Franz J [VerfasserIn]
Wortmann, Gabriele [VerfasserIn]

Links:

Volltext

Themen:

Claim substantiation
Hair Preparations
Hair growth
Intermediate filaments and matrix
Journal Article
Seasonal changes
Statistics
Tensile properties (wet)

Anmerkungen:

Date Completed 03.04.2024

Date Revised 03.04.2024

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1111/ics.12917

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM362673608