SIST EN ISO 23675:2025
(Main)Cosmetics - Sun protection test methods - In vitro determination of sun protection factor (SPF) (ISO 23675:2024)
Cosmetics - Sun protection test methods - In vitro determination of sun protection factor (SPF) (ISO 23675:2024)
This document specifies a method for the in vitro determination of sun protection factor (SPF). This method is applicable to sunscreen products in form of an emulsion or alcoholic one-phase formulation, excluding in form of a loose or compressed powder or stick. Specifications are given to enable determination of the spectral absorbance characteristics of SPF protection in a reproducible manner.
Use of this method is strictly for the determination of a static sun protection factor. It is not applicable for the determination of water-resistance properties of a sun protection product.
Kosmetische Mittel - Untersuchungsverfahren für Sonnenschutzmittel - In vitro Bestimmung des Sonnenschutzfaktors (SSF) (ISO 23675:2024)
Dieses Dokument legt ein Verfahren zur In-vitro-Bestimmung des Sonnenschutzfaktors (SSF) fest. Dieses Verfahren ist anwendbar für Sonnenschutzmittel in Form einer Emulsion oder einer alkoholischen Einphasenrezeptur, ausgenommen Sonnenschutzmittel in Form eines losen oder gepressten Puders oder Stiftes. Es werden Spezifikationen angegeben, die eine reproduzierbare Bestimmung der spektralen Extinktionseigenschaften des SSF-Schutzes ermöglichen.
Dieses Verfahren dient ausschließlich der Bestimmung eines statischen Sonnenschutzfaktors. Für die Bestimmung der Wasserbeständigkeit eines Sonnenschutzmittels ist es nicht anwendbar.
Cosmétiques - Méthodes d’essai de protection solaire - Détermination in vitro du facteur de protection solaire (FPS) (ISO 23675:2024)
Le présent document spécifie une méthode de détermination in vitro du facteur de protection solaire (FPS). Cette méthode est applicable aux produits de protection solaire sous la forme d’émulsion ou de formulation alcoolique monophasée, mais pas à ceux sous la forme de poudre libre ou compacte ou de stick. Des spécifications sont fournies pour permettre de déterminer les caractéristiques d’absorbance spectrale de la protection FPS de façon reproductible.
L’utilisation de la présente méthode est strictement réservée à la détermination d’un facteur de protection solaire statique. Elle n’est pas applicable à la détermination de propriétés de résistance à l’eau d’un produit de protection solaire.
Kozmetika - Preskusne metode za zaščito pred soncem - Določanje faktorja zaščite pred soncem (SPF) in vitro (ISO 23675:2024)
Ta dokument določa metodo za določanje faktorja zaščite pred soncem (SPF) in vitro. Ta metoda se uporablja za izdelke za zaščito pred soncem v obliki emulzije ali alkoholne enofazne formulacije, razen izdelkov v prahu, kamnu ali stiku. Podane specifikacije omogočajo določitev lastnosti spektralne absorpcije zaščite pred žarki SPF na ponovljiv način.
Ta metoda se uporablja izključno za določanje statičnega zaščitnega faktorja zaščite pred soncem. Ne uporablja se za določanje vodoodpornih lastnosti izdelka za zaščito pred soncem.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-marec-2025
Kozmetika - Preskusne metode za zaščito pred soncem - Določanje faktorja
zaščite pred soncem (SPF) in vitro (ISO 23675:2024)
Cosmetics - Sun protection test methods - In vitro determination of sun protection factor
(SPF) (ISO 23675:2024)
Kosmetische Mittel - Untersuchungsverfahren für Sonnenschutzmittel - In vitro
Bestimmung des Sonnenschutzfaktors (SSF) (ISO 23675:2024)
Cosmétiques - Méthodes d’essai de protection solaire - Détermination in vitro du facteur
de protection solaire (FPS) (ISO 23675:2024)
Ta slovenski standard je istoveten z: EN ISO 23675:2025
ICS:
71.100.70 Kozmetika. Toaletni Cosmetics. Toiletries
pripomočki
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 23675
EUROPEAN STANDARD
NORME EUROPÉENNE
January 2025
EUROPÄISCHE NORM
ICS 71.100.70
English Version
Cosmetics - Sun protection test methods - In vitro
determination of sun protection factor (SPF) (ISO
23675:2024)
Cosmétiques - Méthodes d'essai de protection solaire - Kosmetische Mittel - Untersuchungsverfahren für
Détermination in vitro du facteur de protection solaire Sonnenschutzmittel - In vitro Bestimmung des
(FPS) (ISO 23675:2024) Sonnenschutzfaktors (SSF) (ISO 23675:2024)
This European Standard was approved by CEN on 22 November 2024.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 23675:2025 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 23675:2025) has been prepared by Technical Committee ISO/TC 217
"Cosmetics" in collaboration with Technical Committee CEN/TC 392 “Cosmetics” the secretariat of
which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by July 2025, and conflicting national standards shall be
withdrawn at the latest by July 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 23675:2024 has been approved by CEN as EN ISO 23675:2025 without any modification.
International
Standard
ISO 23675
First edition
Cosmetics — Sun protection test
2024-12
methods — In vitro determination
of sun protection factor (SPF)
Cosmétiques — Méthodes d’essai de protection solaire —
Détermination in vitro du facteur de protection solaire (FPS)
Reference number
ISO 23675:2024(en) © ISO 2024
ISO 23675:2024(en)
© ISO 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii
ISO 23675:2024(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles . 4
5 Reagents and/or materials . 4
5.1 Sample substrate — Double plate .4
5.2 Reference sunscreen .4
5.3 Finger-cot .4
5.4 Blank .4
6 Apparatus . 4
6.1 Spectrophotometers .4
6.1.1 Specification .4
6.1.2 Monitoring .5
6.2 Automatic positive-displacement pipette .5
6.3 Analytical balance .5
6.4 Robot .5
6.4.1 Specifications .5
6.4.2 Monitoring .5
6.5 Solar simulator .6
6.5.1 General .6
6.5.2 Quality of solar simulator radiation .6
6.5.3 Maintenance and monitoring the solar simulator .6
7 Procedure . 7
7.1 Outline of the test procedure .7
7.2 Preparation of reagents and materials .8
7.2.1 Plate preparation and handling .8
7.2.2 Finger cot.9
7.3 Product application on plates and robot automatic spreading .9
7.3.1 Weighing of product and application on plates .9
7.3.2 Automatic spreading .10
7.4 Measurement of initial absorbance using two plate types (290 nm to 400 nm) .10
7.4.1 Blank measurement .10
7.4.2 Initial absorbance measurement .10
7.4.3 Calculation of pre-irradiation in vitro SPF .11
i
7.5 Calculation of irradiation dose (based on pre-irradiation in vitro SPF ). 12
i
7.6 Irradiation with calculated dose . 12
7.7 Measurement of post-irradiation absorbance using two plate types . 12
7.8 Calculation of post-irradiation in vitro SPF . 12
i
7.9 Calculation of final in vitro SPF of each pair of plates . 13
i
7.10 Calculation of final in vitro SPF of the product . . 13
7.10.1 General . 13
7.10.2 Validation of final in vitro SPF . 13
8 Test report . 14
Annex A (normative) UV exposure and erythemal action spectra and solar simulator UV
spectrum .16
Annex B (normative) Specification sample plate .20
Annex C (normative) SPF reference sunscreen products .23
Annex D (normative) White petroleum and glycerin .35
iii
ISO 23675:2024(en)
Annex E (normative) Spectrophotometers specification and monitoring .37
Annex F (normative) Robot specification. 41
Bibliography .43
iv
ISO 23675:2024(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
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This document was prepared by Technical Committee ISO/TC 217, Cosmetics, in collaboration with the
European Committee for Standardization (CEN) Technical Committee CEN/TC 392, Cosmetics, in accordance
with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
ISO 23675:2024(en)
Introduction
Chronic exposure to solar ultraviolet radiation (UVR) is the main environmental source of damage to human
skin. Consumer protection against exposure to solar UVB and UVA radiation is, therefore, an important
public health issue. The use of sunscreens is a critical part of holistic programs of consumer UVR protection,
including the use of appropriate clothing, hats and minimising exposure to the sun around its zenith.
The in vivo sun protection factor (SPF) is historically measured by an in vivo method (see ISO 24444) to
[1]
communicate the amplitude of protection offered by sunscreens from erythemally-effective solar UVR.
[2]
In recent years, additional test methods have been developed to measure the breadth of protection from
[3]
solar UVR, namely the in vivo human persistent pigment darkening (PPD) test (and associated UVA-PF)
[4][5][6][7]
and an in vitro equivalent.
Invasive methods based on tests conducted on human beings are ethically problematic, time-consuming and
[8][9][10][11][12][13]
very costly. Therefore, it has for long been a desire to develop an in vitro SPF test method,
[14][15][16][17]
recognising the potential advantages of such methodology, including:
a) the use of a non-human model,
b) the significant improvements in speed and cost,
c) the improved repeatability and reproducibility,
d) the elimination of technically-challenging procedures (e.g., MED determination) and
e) the use of a method which is significantly more amenable to continuous improvement.
This in vitro SPF method is based on UVR transmittance spectroscopy, whereby spectrophotometric
measurement of UVR transmission through appropriate UVR-transparent substrates, allows prediction of in
[18][19][20][21][22]
vivo SPF values. This in vitro SPF method revealed a strong reproducibility and correlation
[23][24][25]
with in vivo SPF values.
vi
International Standard ISO 23675:2024(en)
Cosmetics — Sun protection test methods — In vitro
determination of sun protection factor (SPF)
1 Scope
This document specifies a method for the in vitro determination of sun protection factor (SPF). This method
is applicable to sunscreen products in form of an emulsion or alcoholic one-phase formulation, excluding
in form of a loose or compressed powder or stick. Specifications are given to enable determination of the
spectral absorbance characteristics of SPF protection in a reproducible manner.
Use of this method is strictly for the determination of a static sun protection factor. It is not applicable for
the determination of water-resistance properties of a sun protection product.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 24444, Cosmetics — Sun protection test methods — In vivo determination of the sun protection factor (SPF)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
sunscreen product
product containing any component able to absorb, reflect or scatter UV rays, which are intended to be
placed on the surface of human skin with the purpose of protecting against erythema and other ultraviolet
induced damage
3.2
emulsion
fine dispersion of minute droplets of one liquid in other(s) in which it is not soluble or miscible
3.3
in vitro sun protection factor
SPF
in vitro
protection factor of a sun protection product against erythema-inducing radiation calculated with spectral
modelling between 290 nm and 400 nm
3.4
reference solar spectrum
I (λ)
sol
spectral irradiance of mid-summer sunlight in the spectral range of 290 nm to 400 nm, at a latitude of 40 °N,
a solar zenith angle of 20° and an ozone layer thickness of 0,305 cm, as defined in Annex A
ISO 23675:2024(en)
3.5
solar UVR simulator
solar ultraviolet radiation simulator
light source emitting a continuous spectrum [S(λ)] with no gaps or extreme peaks of emission in the UV region
Note 1 to entry: The solar simulator has a spectral quality that complies with the required acceptance limits in
Annex A.
3.6
erythemal action spectrum
E(λ)
relative effects of individual spectral bands of an exposure source for an erythema response
Note 1 to entry: The symbol for the erythemal action spectrum is defined as s (λ) in ISO/CIE 17166 and E(λ) in the
er
ISO 24443.
Note 2 to entry: This entry was numbered 17-401 in CIE S 017:2011.
[SOURCE: CIE-ILV 17-26-065]
3.7
spectrophotometer
instrument for measuring the ratio of 2 values of a radiometric quantity at the same wavelength
Note 1 to entry: This entry was numbered 17-1235 in CIE S 017:2011.
[SOURCE: CIE-ILV 17-25-008]
3.8
monochromatic absorbance
A(λ)
sunscreen absorbance at wavelength λ calculated as logarithm to base 10 of the reciprocal of the spectral
internal transmittance, T(λ)
A(λ) = -log10 T(λ)
Note 1 to entry: This entry was numbered 17-1207 in CIE S 017:2011.
[SOURCE: CIE-ILV 17-24-090]
3.9
irradiance at a point of surface
I(λ)
quotient of the radiant flux dΦe incident on an element of the surface containing the point, by the area dA of
that element
-2
Note 1 to entry: Expressed in W·m .
Note 2 to entry: Note that the symbol for the irradiance is defined as E in CIE-ILV 017:2020 but because it could be
confused with the symbol used in ISO 24443:2021 for the erythemal action spectrum, here we use I(λ).
Note 3 to entry: This entry was numbered 17-608 in CIE S 017:2011.
[SOURCE: CIE-ILV 17-21-053]
3.10
spectroradiometer
instrument for measuring radiometric quantities in narrow wavelength intervals over a given spectral region
Note 1 to entry: This entry was numbered 17-1236 in CIE S 017:2011.
[SOURCE: CIE-ILV 17-25-007]
ISO 23675:2024(en)
3.11
radiometer
instrument for measuring the intensity of electromagnetic radiation (UV radiation specifically for this
standard)
Note 1 to entry: In the context of this document, a UV radiometer measures the irradiance for the UV spectral range
from 290 nm to 400 nm.
Note 2 to entry: This entry was numbered 17-1031 in CIE S 017:2011.
[SOURCE: CIE-ILV 17-25-006]
3.12
reference sunscreen formula
product used to validate the testing procedure
3.13
dose
-2
UV exposure dose (J·m ) for pre-irradiation of sunscreen products
Note 1 to entry: The UV dose is the product of UV intensity (expressed as energy per unit surface area) and time.
3.14
plate
piece of polymethylmethracylate (PMMA) on which test product is to be applied for absorbance
measurements
Note 1 to entry: See Annex B.
3.15
erythemal irradiance
I (λ)
ER
effective irradiance computed from the product of the spectral irradiance, I(λ) and the erythema spectral
weighting function, s (λ)
er
-2
Note 1 to entry: Expressed in W⋅m .
Note 2 to entry: This entry was numbered 17-403 in CIE S 017:2011.
[SOURCE: CIE-ILV 17-26-067]
3.16
UVB
electromagnetic radiation in the range of 290 nm to 320 nm
3.17
UVA
electromagnetic radiation in the range of 320 nm to 400 nm
3.18
UVA-I
electromagnetic radiation in the range of 340 nm to 400 nm
3.19
UVA-II
electromagnetic radiation in the range of 320 nm to 340 nm
3.20
percentage relative cumulative erythemal effectiveness
% RCEE
description of the spectral distribution of the solar simulator in terms of cumulative erythemal effective
irradiance by successive wavelength bands, as defined in Annex A
ISO 23675:2024(en)
4 Principles
The test is based on the assessment of UV-transmittance through a thin film of sunscreen spread on at
least three moulded PMMA plates and on at least three sandblasted surface PMMA plates, before and after
exposure to a controlled dose of radiation from a solar simulator. Samples submitted for testing should not
have a SPF or UVA-PF target or other protection category description.
5 Reagents and/or materials
5.1 Sample substrate — Double plate
Moulded and sandblasted PMMA plates shall be used for sunscreen application according to this method
(see Annex B).
5.2 Reference sunscreen
The formulae details and manufacturing instructions for the reference formulations are given in Annex C. At
least once a month, the following reference standards shall be tested: P2 or P3 reference standard, and P5
or P6 reference standard, and P8 reference standard. The results shall be within the respective acceptance
ranges given in Table C.1, Annex C.
5.3 Finger-cot
Finger-cots should be manufactured from untextured and un-powdered latex. As example, for a probe as
F.2, a finger-cot of a medium size should be used. If alternative finger-cots are used, a validated equivalent
result shall be demonstrated in this method. The finger-cot should be tight on the robot finger probe without
ripples or breaks where product can get caught.
5.4 Blank
Glycerin or a modified glycerin solution (see Table B.1), or white petroleum in accordance with Annex D shall
be used for blank measurement.
6 Apparatus
6.1 Spectrophotometers
6.1.1 Specification
The spectrophotometer shall span the spectral range from 290 nm to 400 nm. The wavelength increment
step shall be 1 nm. A spectrophotometer that does not use a monochromator to analyse the reflected or
transmitted radiation from the test sample should employ a fluorescence rejection filter. Its input optics
should be designed for diffuse illumination and/or diffuse collection of the transmitted irradiance through
the roughened polymethylmethacrylate (PMMA)plate, with and without the sunscreen layer spread on its
surface. The size of the diameter of the entrance port of the spectrophotometer probe should be smaller
than the size of the light spot to be measured at the sample level (in order to account for stray light). The
area of each reading site shall be at least 0,5 cm in order to reduce the variability between readings and
to compensate for the lack of uniformity in the product layer. The wavelength should be accurate to within
1 nm, as checked using a holmium-doped filter (see Annex E). The ability of an instrument to accurately
measure absorbance is limited by the sensitivity of the instrument. The minimum required dynamic range
for this methodology is 2,2 absorbance units as determined in accordance with Annex E. The maximum
measured absorbance should be within the dynamic range of the device used. If the test measurements yield
absorbance curves that exceed the determined upper limit of the spectrophotometer, the product should be
re-tested using an instrument with increased sensitivity and dynamic range.
ISO 23675:2024(en)
In order to minimise scatter, the distance between the closest side of the plate and the emission source or
the integrating sphere should not be more than 2 mm. The plate shall be positioned in a horizontal plane
during all steps including UV measurement steps.
The lamp in the spectrophotometer (or spectroradiometer) that is used to measure the absorbance shall emit
a continuous spectrum of radiation (with no gaps or extreme peaks of emission in the UV region) over the
range of 290 nm to 400 nm, and the level of irradiance should be sufficiently low, so that the photostability
of the product is not unduly challenged, wherein the UV dose during one measurement cycle should not
-2
exceed 0,2 J·cm .
6.1.2 Monitoring
The spectrophotometer shall be validated every month by measurements of reference materials.
A four-fold test is required, as described in Annex E:
— dynamic range of the spectrophotometer;
— linearity test of the spectrophotometer;
— wavelength trueness test;
— absolute transmission trueness.
6.2 Automatic positive-displacement pipette
Positive displacement pipettes, micro-pipettes, automatic pipettes or any similar device should use piston-
driven displacement and shall be capable of delivering accurate and repeatable aliquots of approximately
1,6 mg to 1,8 mg of a sunscreen product (as described in 7.3.1).
NOTE 1,6 mg to 1,8 mg correspond to approximately 1,6 µl to 1,8 µl, respectively.
6.3 Analytical balance
-4
A laboratory balance with at least 10 g precision shall be used.
6.4 Robot
6.4.1 Specifications
The robot shall be in accordance with Annex F and shall have:
a) positional repeatability of at least ±0,1 mm in x, y and z axes,
b) degrees of freedom equal to at least 6 rotating joints,
c) a payload of at least 0,5 kg,
d) a vertical force (z axis), measured in the centre of the plate (with the finger tool and finger cot, without x
and y axis movement), of (6,0 ± 0,5) N.
6.4.2 Monitoring
The robotic appliance shall be checked by a suitably qualified expert at regular intervals (at least every
twelve months) to ensure compliance to the mechanical and spreading specifications given in 6.4.1.
The finger tool shall be replaced after every cycle of 400 spreading operations or when damaged (e.g.
cracks, etc.).
ISO 23675:2024(en)
6.5 Solar simulator
6.5.1 General
A xenon arc solar simulator with appropriate filters should be used and shall conform with the spectral
specifications described in Table A.1 and Figure A.1. It shall be able to maintain a stable plate temperature
of (27 ± 2) °C.
6.5.2 Quality of solar simulator radiation
The output from the solar UVR simulator shall be continuous, uniform, stable, with no gaps or extreme
peaks of emission in the UVR region and suitably filtered to create a spectral quality that complies with the
required acceptance limits (see Table A.1).
To ensure that appropriate amounts of UVA radiation are included in the spectrum of the solar UV
simulator, the total radiometric proportion of UVA-II irradiance of the simulator (320 nm to 340 nm) shall
be ≥ 20,0 % of total UVR irradiance (290 nm to 400 nm) in accordance with ISO 24444 which requires the
same solar irradiance. Additionally, UVA-I region (340 nm to 400 nm) irradiance shall be ≥ 60 % of total
UVR irradiance. The source spectral specification is described in terms of cumulative erythemal effective
irradiance by successive wavelength bands, 290 nm to 400 nm. The erythemal effective irradiance of each
wavelength band is expressed as a percentage of total erythemal effective irradiance, 290 nm to 400 nm, or
as percentage relative cumulative erythemal effectiveness (%RCEE). The calculation of %RCEE values shall
be in accordance with Annex A, where acceptance limits are shown in Table A.1.
-2
Total irradiance shall not exceed 200 W·m . The output of the solar simulator shall be measured with a
broad-spectrum sensor (capable of measuring between 280 nm and 1 600 nm) calibrated against a standard
reference source over the range of 280 nm to 1 600 nm. Alternatively, the source may be measured with a
calibrated spectroradiometer over this same wavelength range to determine the total irradiance.
In broad-beam UV-sources, spectra from different locations under the beam shall be recorded over at least
5 different locations (a location is defined for each plate) in order to account for uniformity.
The uniformity shall be ≥ 90 % as calculated by Formula (1):
U = (1-(max-min)/(X̅ )) (1)
where
U is the uniformity in percentage;
X̅ is the average.
If the uniformity is less than 90 %, then optical components should be adjusted (and a new beam uniformity
control shall be performed) or appropriate compensation for different irradiance shall be made in the
exposure time on each plate.
6.5.3 Maintenance and monitoring the solar simulator
The emission of the UV exposure source used for exposure shall be checked for compliance with the given
acceptance limits by a suitably qualified expert (at least) every 12 months, or 2 500 h of lamp running time
and after changing any significant physical (optical) component of the solar simulator (including the bulb only
if the bulb was not already previously calibrated with the associated solar simulator). The inspection should
be conducted with a spectroradiometer that has been calibrated against a standard lamp that is traceable
to a national or an international calibration standard. Prior to the UV exposure of sample, the UV intensity
of the exposure source output shall be measured and recorded with a spectroradiometer (as detailed in 6.1)
or an erythema weighted radiometer cross-calibrated against a spectroradiometric measurement of each
assigned solar simulator output as detailed in 6.5.2. Optical alignment shall be configured to ensure accurate
radiometer alignment and reproduction of the assigned simulator output at the same optical reference
ISO 23675:2024(en)
plane measured with the spectroradiometer. A calibration factor Y for each radiometer with assigned solar
simulator output shall be determined by Formula (2):
Y = I /I (2)
ersp err
where
Y is the calibration factor for each radiometer;
I is I(λ) × s (λ) measured by the spectroradiometer;
ersp er
I is I(λ) × s (λ) measured by the radiometer.
err er
7 Procedure
7.1 Outline of the test procedure
1) Preparation of reagents and materials.
2) Product application on plates and robot automatic spreading.
3) Measurement of initial absorbance using two plate types (290 nm to 400 nm).
4) Calculation of initial in vitro SPF.
5) Calculation of irradiation dose (based on initial in vitro SPF).
6) Irradiation with calculated dose.
7) Measurement of final post-irradiation absorbance using two plate types (290 nm to 400 nm).
8) Calculation of final in vitro SPF.
See Figure 1.
ISO 23675:2024(en)
a
Incubation at (27 ± 2) °C, at least 12 h before.
b
Finger tool and finger cot installation.
c
At least three moulded PMMA plates and three sandblasted plates.
d
Product deposit.
e
Spreading and drying step.
f
First absorbance measurements.
g
UV exposure.
h
Second absorbance measurements.
Figure 1 — Key steps of the method
7.2 Preparation of reagents and materials
7.2.1 Plate preparation and handling
Three (at least) moulded PMMA plates and three (at least) sandblasted plates shall be used, each in
accordance with the specifications in Annex B.
Plates and product shall be stored, in the dark, at (27 ± 2) °C for at least twelve hours before the start of the test.
The surface of sandblasted plates should be cleaned with a dry, antistatic microfibre cloth.
The plates should be handled carefully by holding them by the edges, avoiding finger contact with the
surface.
A reference mark should be made on edge of each plate, outside of spreading area, to ensure the whole
measurement process proceeds in the same order with plate placed in same orientation each time.
The plates shall be used without additional treatment on surface (chemical and/or physical). The plates shall
be used only once.
ISO 23675:2024(en)
7.2.2 Finger cot
7.2.2.1 Preparation
A latex finger-cot is first placed on the robot finger probe. It is important to verify that there are no creases in
the finger-cot after fitting and to verify that the finger cot remains firmly in place and does not break during
the spreading procedure. If creases should appear on the finger-cot or if it breaks during the spreading
procedure, it shall be replaced, and the plate currently being spread shall be discarded.
7.2.2.2 Saturation
To ensure saturation of the finger cot, a standard spreading procedure is first performed with a moulded
PMMA plate, using the same protocol as described in 7.3. This plate shall be discarded and is not part of the
final calculation. The same finger cot can be used for the complete set of plates of one product test, unless it
gets damaged in the process. Each time that there is a change in finger cot, the saturation procedure shall be
repeated.
7.3 Product application on plates and robot automatic spreading
7.3.1 Weighing of product and application on plates
Liquid sunscreen products shall be shaken well before application to the plates.
Plates shall, first of all, be placed onto the weighing pan of an analytical balance (with the roughened side
uppermost), in order to check the weight of the plate before and after application of product.
Using an automatic positive-displacement pipette capable of dispensing repeated identical aliquots of
product:
-2 [17][19]
— moulded plate: 1,3 mg.cm (±1,6 %) of product is applied to each plate; ;
-2 [17][19]
— sandblasted plate: 1,2 mg.cm (±1,5 %) of the same product is applied to each plate.
NOTE 1 For viscous/gelled products for which the use of an automatic volumetric pipette would be difficult, the
sampling speed can be reduced or the end of the tip can be cut to widen the opening. If these measurements remain
insufficient, another tool can be used, such as a spatula by applying a minimum of 12 points (ideally 16 points) evenly.
For the alcoholic one phase formulations, the application dose shall be determined while reducing the
evaporation lost during application.
NOTE 2 For application of the alcoholic one phase formulations, when the type of plates allows it, the plates can
be tared by superimposing 2 plates on top of each other (plate A-2 on the top of the plate A-1). The product is applied
on the plate below (plate A-1), then immediately covered by the one above (plate A-2) to limit evaporation during
weighing control. The 2 plates (plate A-1 and plate A-2) are then placed on the robot platform and the top plate (plate
A-2) is removed just as the spreading process begins.
Spray products supplied in a pressure container shall first be sprayed in a jar or be degassed by puncturing
a very small pinhole in the container to relieve all of the pressure, then left to stand for at least 24 h at room
temperature before accessing the liquid to be tested.
Spreading area is defined as the whole area of the plate. Droplet application should be uniform, achieved
with at least 16 equally-spaced droplets of approximately 1,6 mg to 1,8 mg each (depending on the density of
the applied products; as described in the diagram here after for example) as Figure 2.
NOTE 3 1,6 mg to 1,8 mg correspond to approximately 1,6 µl to 1,8 µl, respectively.
ISO 23675:2024(en)
Figure 2 — Diagram of droplet application
If the applied weight is too low, up to four more equal droplets can be added to the plate in a uniform manner,
to achieve the desired target final weight. If the applied weight is too high, product can be removed carefully
using the pipette tip, until the desired weight is achieved.
Deposit and weighing shall not take more than 30 s. After the sunscreen product is deposited on the surface
of the plate, it shall be spread immediately over the whole surface.
7.3.2 Automatic spreading
Once the product is deposited on plates (refer to 7.3.1), each plate is immediately placed on the measurement
stage of the robot and the automated spreading sequence starts (see Figure F.1 and Figure F.2). For each
plate, the time between the start of droplet application and placing the plate on the robot measurement
stage shall be no more than 30 s. The spreading should be completed within one minute after placing of the
plate on the robot measurement stage.
Immediately after the robot application sequence stops, the plates shall be placed in a dark environment for
at least 30 min (up to a maximum of 60 min) at (27 ± 2) °C.
7.4 Measurement of initial absorbance using two plate types (290 nm to 400 nm)
7.4.1 Blank measurement
It is necessary to first determine the absorbance of UVR radiation through “blank” PMMA plates to establish
the baseline for the measurement device. Therefore, a “blank” plate should be prepared for both moulded
and sandblasted plates by spreading a few microlitres of glycerine/white petroleum on the roughened side
of the plate. This “blank” measurement should be done at least with each new batch of plates. The amount of
glycerine/modified glycerine solution/white petroleum should be such that the entire surface is completely
covered without excess (approximately 15 mg for a 50 mm ⨯ 50 mm ± 4 % plate)
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