Problems of in vitro SPF measurements brought about by viscous fingering generated during sunscreen applications

K. Fujikake, S. Tago, R. Plasson, R. Nakazawa, K. Okano, D. Maezawa, T. Mukawa, A. Kuroda, Kouichi Asakura

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Up to date, no worldwide standard in vitro method has been established for the determination of the sun protection factor (SPF), since there are many problems in terms of its repeatability and reliability. Here, we have studied the problems on the in vitro SPF measurements brought about by the phenomenon called viscous fingering. A spatially periodic stripe pattern is usually formed spontaneously when a viscous fluid is applied onto a solid substrate. For the in vitro SPF measurements, the recommended amount of sunscreen is applied onto a substrate, and the intensity of the transmitted UV light through the sunscreen layer is evaluated. Our theoretical analysis indicated that the nonuniformity of the thickness of the sunscreen layer varied the net UV absorbance. Pseudo-sunscreen composites having no phase separation structures were prepared and applied on a quartz plate for the measurements of the UV absorbance. Two types of applicators, a block applicator and a 4-sided applicator were used. The flat surface was always obtained when the 4-sided applicator was used, while the spatially periodic stripe pattern was always generated spontaneously when the block applicator was used. The net UV absorbance of the layer on which the stripe pattern was formed was found to be lower than that of the flat layer having the same average thickness. Theoretical simulations quantitatively reproduced the variation of the net UV absorbance led by the change of the geometry of the layer. The results of this study propose the definite necessity of strict regulations on the coating method of sunscreens for the establishment of the in vitro SPF test method.

Original languageEnglish
Pages (from-to)254-262
Number of pages9
JournalSkin Pharmacology and Physiology
Volume27
Issue number5
DOIs
Publication statusPublished - 2014

Fingerprint

Sun Protection Factor
Sunscreening Agents
Quartz
Ultraviolet Rays
In Vitro Techniques

Keywords

  • In vitro measurement
  • Simulation
  • Spontaneous pattern formation
  • Sun protection factor
  • Sunscreen application
  • Ultraviolet absorbance
  • Viscous fingering

ASJC Scopus subject areas

  • Pharmacology
  • Physiology
  • Dermatology
  • Medicine(all)

Cite this

Problems of in vitro SPF measurements brought about by viscous fingering generated during sunscreen applications. / Fujikake, K.; Tago, S.; Plasson, R.; Nakazawa, R.; Okano, K.; Maezawa, D.; Mukawa, T.; Kuroda, A.; Asakura, Kouichi.

In: Skin Pharmacology and Physiology, Vol. 27, No. 5, 2014, p. 254-262.

Research output: Contribution to journalArticle

Fujikake, K, Tago, S, Plasson, R, Nakazawa, R, Okano, K, Maezawa, D, Mukawa, T, Kuroda, A & Asakura, K 2014, 'Problems of in vitro SPF measurements brought about by viscous fingering generated during sunscreen applications', Skin Pharmacology and Physiology, vol. 27, no. 5, pp. 254-262. https://doi.org/10.1159/000356298
Fujikake, K. ; Tago, S. ; Plasson, R. ; Nakazawa, R. ; Okano, K. ; Maezawa, D. ; Mukawa, T. ; Kuroda, A. ; Asakura, Kouichi. / Problems of in vitro SPF measurements brought about by viscous fingering generated during sunscreen applications. In: Skin Pharmacology and Physiology. 2014 ; Vol. 27, No. 5. pp. 254-262.
@article{244838f195e148d2899455cced811973,
title = "Problems of in vitro SPF measurements brought about by viscous fingering generated during sunscreen applications",
abstract = "Up to date, no worldwide standard in vitro method has been established for the determination of the sun protection factor (SPF), since there are many problems in terms of its repeatability and reliability. Here, we have studied the problems on the in vitro SPF measurements brought about by the phenomenon called viscous fingering. A spatially periodic stripe pattern is usually formed spontaneously when a viscous fluid is applied onto a solid substrate. For the in vitro SPF measurements, the recommended amount of sunscreen is applied onto a substrate, and the intensity of the transmitted UV light through the sunscreen layer is evaluated. Our theoretical analysis indicated that the nonuniformity of the thickness of the sunscreen layer varied the net UV absorbance. Pseudo-sunscreen composites having no phase separation structures were prepared and applied on a quartz plate for the measurements of the UV absorbance. Two types of applicators, a block applicator and a 4-sided applicator were used. The flat surface was always obtained when the 4-sided applicator was used, while the spatially periodic stripe pattern was always generated spontaneously when the block applicator was used. The net UV absorbance of the layer on which the stripe pattern was formed was found to be lower than that of the flat layer having the same average thickness. Theoretical simulations quantitatively reproduced the variation of the net UV absorbance led by the change of the geometry of the layer. The results of this study propose the definite necessity of strict regulations on the coating method of sunscreens for the establishment of the in vitro SPF test method.",
keywords = "In vitro measurement, Simulation, Spontaneous pattern formation, Sun protection factor, Sunscreen application, Ultraviolet absorbance, Viscous fingering",
author = "K. Fujikake and S. Tago and R. Plasson and R. Nakazawa and K. Okano and D. Maezawa and T. Mukawa and A. Kuroda and Kouichi Asakura",
year = "2014",
doi = "10.1159/000356298",
language = "English",
volume = "27",
pages = "254--262",
journal = "Skin Pharmacology and Physiology",
issn = "1660-5527",
publisher = "S. Karger AG",
number = "5",

}

TY - JOUR

T1 - Problems of in vitro SPF measurements brought about by viscous fingering generated during sunscreen applications

AU - Fujikake, K.

AU - Tago, S.

AU - Plasson, R.

AU - Nakazawa, R.

AU - Okano, K.

AU - Maezawa, D.

AU - Mukawa, T.

AU - Kuroda, A.

AU - Asakura, Kouichi

PY - 2014

Y1 - 2014

N2 - Up to date, no worldwide standard in vitro method has been established for the determination of the sun protection factor (SPF), since there are many problems in terms of its repeatability and reliability. Here, we have studied the problems on the in vitro SPF measurements brought about by the phenomenon called viscous fingering. A spatially periodic stripe pattern is usually formed spontaneously when a viscous fluid is applied onto a solid substrate. For the in vitro SPF measurements, the recommended amount of sunscreen is applied onto a substrate, and the intensity of the transmitted UV light through the sunscreen layer is evaluated. Our theoretical analysis indicated that the nonuniformity of the thickness of the sunscreen layer varied the net UV absorbance. Pseudo-sunscreen composites having no phase separation structures were prepared and applied on a quartz plate for the measurements of the UV absorbance. Two types of applicators, a block applicator and a 4-sided applicator were used. The flat surface was always obtained when the 4-sided applicator was used, while the spatially periodic stripe pattern was always generated spontaneously when the block applicator was used. The net UV absorbance of the layer on which the stripe pattern was formed was found to be lower than that of the flat layer having the same average thickness. Theoretical simulations quantitatively reproduced the variation of the net UV absorbance led by the change of the geometry of the layer. The results of this study propose the definite necessity of strict regulations on the coating method of sunscreens for the establishment of the in vitro SPF test method.

AB - Up to date, no worldwide standard in vitro method has been established for the determination of the sun protection factor (SPF), since there are many problems in terms of its repeatability and reliability. Here, we have studied the problems on the in vitro SPF measurements brought about by the phenomenon called viscous fingering. A spatially periodic stripe pattern is usually formed spontaneously when a viscous fluid is applied onto a solid substrate. For the in vitro SPF measurements, the recommended amount of sunscreen is applied onto a substrate, and the intensity of the transmitted UV light through the sunscreen layer is evaluated. Our theoretical analysis indicated that the nonuniformity of the thickness of the sunscreen layer varied the net UV absorbance. Pseudo-sunscreen composites having no phase separation structures were prepared and applied on a quartz plate for the measurements of the UV absorbance. Two types of applicators, a block applicator and a 4-sided applicator were used. The flat surface was always obtained when the 4-sided applicator was used, while the spatially periodic stripe pattern was always generated spontaneously when the block applicator was used. The net UV absorbance of the layer on which the stripe pattern was formed was found to be lower than that of the flat layer having the same average thickness. Theoretical simulations quantitatively reproduced the variation of the net UV absorbance led by the change of the geometry of the layer. The results of this study propose the definite necessity of strict regulations on the coating method of sunscreens for the establishment of the in vitro SPF test method.

KW - In vitro measurement

KW - Simulation

KW - Spontaneous pattern formation

KW - Sun protection factor

KW - Sunscreen application

KW - Ultraviolet absorbance

KW - Viscous fingering

UR - http://www.scopus.com/inward/record.url?scp=84902030747&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84902030747&partnerID=8YFLogxK

U2 - 10.1159/000356298

DO - 10.1159/000356298

M3 - Article

C2 - 24923467

AN - SCOPUS:84902030747

VL - 27

SP - 254

EP - 262

JO - Skin Pharmacology and Physiology

JF - Skin Pharmacology and Physiology

SN - 1660-5527

IS - 5

ER -