CEN/TS 927-12:2023
(Main)Paints and varnishes - Coating materials and coating systems for exterior wood - Part 12: Ultraviolet and visible radiation transmittance
Paints and varnishes - Coating materials and coating systems for exterior wood - Part 12: Ultraviolet and visible radiation transmittance
This Technical Specification describes a test method to measure the ultraviolet (UV) and visible (VIS) spectral transmittance in the wavelength range from 280 nm to 700 nm of coatings for exterior wood. From the spectral transmittance the transmittance of UV, VIS and the UV plus VIS wavelength range can be calculated.
It is applicable to free coatings films or coatings applied on a UV-transparent substrate.
Beschichtungsstoffe - Beschichtungsstoffe und Beschichtungssysteme für Holz im Außenbereich - Teil 12: Durchlässigkeit für ultraviolette und sichtbare Strahlung
Dieses Dokument beschreibt ein Prüfverfahren zum Messen des spektralen Transmissionsgrades von Beschichtungen für Holz im Außenbereich für ultraviolette Strahlung und sichtbares Licht im Wellenlängenbereich von 280 nm bis 700 nm. Aus dem spektralen Transmissionsgrad kann der Transmissionsgrad für den UV , den VIS- und den kombinierten UV und VIS Wellenlängenbereich errechnet werden.
Es ist auf direkt aufgetragene Beschichtungsfilme und auf Beschichtungen anwendbar, die auf ein UV transparentes Substrat aufgetragen werden.
Peintures et vernis - Produits de peinture et systèmes de peinture pour le bois extérieur - Partie 12: Transmission du rayonnement ultraviolet et visible
Barve in laki - Premazi in premazni sistemi za zaščito lesa za zunanjo uporabo - 12. del: Prepustnost ultravijoličnih in vidnih žarkov
Ta tehnična specifikacija opisuje preskusno metodo za merjenje ultravijolične (UV) in vidne (VIS) spektralne prepustnosti v območju valovne dolžine od 280 nm do 700 nm za premaze za zaščito lesa za zunanjo uporabo. Na podlagi spektralne prepustnosti je mogoče izračunati prepustnost v območju valovne dolžine UV, VIS in UV plus VIS.
Uporablja se za prozorne premaze ali premaze, nanesene na UV-prosojno podlago.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2023
Barve in laki - Premazi in premazni sistemi za zaščito lesa za zunanjo uporabo - 12.
del: Prepustnost ultravijoličnih in vidnih žarkov
Paints and varnishes - Coating materials and coating systems for exterior wood - Part
12: Ultraviolet and visible radiation transmittance
Beschichtungsstoffe - Beschichtungsstoffe und Beschichtungssysteme für Holz im
Außenbereich - Teil 12: Durchlässigkeit für ultraviolette und sichtbare Strahlung
Peintures et vernis - Produits de peinture et systèmes de peinture pour le bois extérieur -
Partie 12: Transmission du rayonnement ultraviolet et visible
Ta slovenski standard je istoveten z: CEN/TS 927-12:2023
ICS:
71.100.50 Kemikalije za zaščito lesa Wood-protecting chemicals
87.040 Barve in laki Paints and varnishes
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
CEN/TS 927-12
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
May 2023
TECHNISCHE SPEZIFIKATION
ICS 87.040
English Version
Paints and varnishes - Coating materials and coating
systems for exterior wood - Part 12: Ultraviolet and visible
radiation transmittance
Peintures et vernis - Produits de peinture et systèmes Beschichtungsstoffe - Beschichtungsstoffe und
de peinture pour le bois extérieur - Partie 12: Beschichtungssysteme für Holz im Außenbereich - Teil
Transmission du rayonnement ultraviolet et visible 12: Durchlässigkeit für ultraviolette und sichtbare
Strahlung
This Technical Specification (CEN/TS) was approved by CEN on 24 March 2023 for provisional application.
The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to
submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.
CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS
available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in
parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.
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
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 927-12:2023 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Abbreviations . 5
5 Principle . 6
6 Apparatus and materials . 6
6.1 Film applicator for coating material . 6
6.2 Substrate for free coating film preparation . 6
6.2.1 Preparation of free film and test specimen . 6
6.2.2 Coating application . 6
6.3 Film thickness measurement . 7
6.4 UV/VIS spectrophotometer . 7
6.5 Long-pass filter specification for check . 8
7 Test procedure . 8
7.1 Test procedure with spectrophotometer . 8
7.2 Check of spectrophotometer with long-pass filter . 9
7.3 Spectral transmittance of the specimen (film) . 9
7.4 Calculation of transmittance. 10
8 Precision . 10
9 Test report . 10
Annex A (normative) Spectral transmittance of long-pass filter . 12
Annex B (informative) Application and evaluation references . 13
Bibliography . 14
European foreword
This document (CEN/TS 927-12:2023) has been prepared by Technical Committee CEN/TC 139 “Paints
and varnishes — Coating materials and coating systems for exterior wood — Ultraviolet and visible
radiation transmittance”, the secretariat of which is held by DIN.
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.
A complete listing of these bodies can be found on the CEN website.
According to the CEN/CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to announce this Technical Specification: 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.
FprCEN/TS 927-12:2022 (E)
Introduction
Wood is a natural material that must be protected against solar radiation, heat, rain, and microorganisms
to maintain its appearance and mechanical integrity when used outdoors. Wood and its components
(especially lignin) are sensitive to photo oxidation and must therefore be protected by suitable coatings,
particularly against ultraviolet (UV) and visible (VIS) radiation in the violet and blue region.
Clear and transparent coating films may be modified by fine sized transparent (mostly yellow or red
ferrous oxide-based) pigments and more or less colourless, organic and inorganic UV-absorbers to reduce
the harmful part of solar radiation. As these additives are not visible, there is a demand for a test method
to determine their efficiency.
The transmittance in a specific wavelength range allows to evaluate the UV and VIS radiation protection
of a coating film.
1 Scope
This document describes a test method to measure the ultraviolet (UV) and visible (VIS) spectral
transmittance in the wavelength range from 280 nm to 700 nm of coatings for exterior wood. From the
spectral transmittance the transmittance of UV, VIS and the combined UV and VIS wavelength range can
be calculated.
It is applicable to free coatings films or coatings applied on a UV-transparent substrate.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
EN ISO 2808, Paints and varnishes - Determination of film thickness (ISO 2808)
EN ISO 4618, Paints and varnishes - Terms and definitions (ISO 4618)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN ISO 4618 and the following
apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
transmittance
τ
quotient of transmitted radiant flux, Φ , and incident radiant flux, Φ
t m
Φ
t
τ=
Φ
m
Note 1 to entry: Transmittance is also defined spectrally in terms of wavelength, in which case, “spectral” is added
before the quantity name.
Note 2 to entry: Due to energy conservation, α + ρ + τ = 1 except when polarized radiation is observed, where α is
absorptance and ρ is reflectance.
Note 3 to entry: Transmittance, τ, is the sum of regular transmittance, τr, and diffuse transmittance, τd: τ = τr + τd.
Note 4 to entry: The transmittance has unit one.
[SOURCE: CIE S 017:2020]
4 Abbreviations
UV ultraviolet radiation in the wavelength range from 280 nm to 400 nm
VIS visible radiation in the wavelength range from 400 nm to 700 nm
FprCEN/TS 927-12:2022 (E)
5 Principle
The UV and VIS transmittance through a coating film is measured using an UV/VIS spectrophotometer
equipped with a radiation source, a limiting aperture, an integrating sphere (Ulbricht sphere), and a
spectroradiometer with a diffraction element and a detector.
A beam of optical radiation, limited by an aperture, with an incident radiant flux Φ is directed on a film
m
specimen. The transmitted radiant flux Φ enters an integrating sphere. The sphere is equipped with the
t
input optics of a spectroradiometer with which spectrally resolved measurements of the unfiltered Φ(λ)
m
and the filtered (transmitted) radiant flux Φ(λ) can be performed. The quotient Φ(λ)/Φ (λ) is the
t t m
spectral transmittance τ(λ). τ(λ) multiplied by 100 represents the percentage of the transmitted radiant
flux at a specific wavelength or wavelength range passing through the film compared to the incident
radiant flux Φ (λ). From the spectral transmittance, the transmittance in a specific wavelength range can
m
be calculated as described in 7.4.
The spectral transmittance is recorded in wavelength increments over the entire wavelength range of
280 nm to 700 nm continuously during a wavelength scanning (e.g. in 2 nm to 10 nm steps depending on
the apparatus used and the resolution needed). Depending on the application the transmittance of the
specific wavelength ranges for UV, VIS, and UV+VIS can be calculated.
6 Apparatus and materials
6.1 Film applicator for coating material
A suitable doctor blade to apply coatings films of defined wet layer thickness shall be used. As an example
for high build wood stains a dry film thickness of approximately 90 µm to 120 µm should be achieved.
6.2 Substrate for free coating film preparation
6.2.1 Preparation of free film and test specimen
A clean and plane substrate shall be used to apply the wet coating materials to prepare the free coating
films of correct uniform layer thickness. Ideal as substrate to separate later the coating film without
1)
damage is a PTFE coated smooth metal plate or a PE-, PP-foil, or silicone paper fixed on e.g. a smooth
glass or metal plate. In case of low viscosity coatings silicone rubber rings can be used after balancing
them horizontally, on e.g. a glass plate to fill in the liquid coating material. The coating material normally
is sufficiently dry after a minimum of 7 days or better of 28 days at (23 ± 2) °C at (50 ± 5) % relative
humidity (according to EN 23270) or as per the coating supplier’s specification.
NOTE Soaking in water is another suitable method for the detachment of free films from a substrate. But this
method of preparation of free films can influence the test results. The usual method for preparation of free films is
without using water on a low energy substrate such as polypropylene. Alternatively, the coatings can be measured
directly on a UV-transparent substrate like quartz.
For each coating, a minimum of three specimens shall be cut out from a uniform section of the film
without any damages. The size of the specimens shall be adjusted to the specific spectrophotometer
under use.
6.2.2 Coating application
The coating shall be applied on a 1 mm to 2 mm thick quartz substrate with a spectral transmittance of
at least 90 % in the wavelength range from 280 nm to 700 nm.
1)
PTFE – Poly tetra fluoro ethylene.
----------------------
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.