INTERNATIONAL ISO

STANDARD 2810

Third edition
2020-09

Paints and varnishes — Natural

weathering of coatings — Exposure
and assessment
Peintures et vernis — Vieillissement naturel des revêtements —
Exposition et évaluation

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ISO 2810:2020
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bcb853a24b3b/iso-2810-2020

Reference number
ISO 2810:2020(E)

© ISO 2020
ISO 2810:2020(E)


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ISO 2810:2020
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bcb853a24b3b/iso-2810-2020

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Contents Page

Foreword......................................................................................................................................................................................................................................... iv
1 Scope.................................................................................................................................................................................................................................. 1
2 Normative references....................................................................................................................................................................................... 1
3 Terms and definitions...................................................................................................................................................................................... 1
4 General............................................................................................................................................................................................................................. 1
5 Exposure racks........................................................................................................................................................................................................ 2
6 Apparatus for measurement of climatic factors................................................................................................................... 3
6.1 Measurement of solar radiation................................................................................................................................................ 3
6.1.1 Pyranometers...................................................................................................................................................................... 3
6.1.2 Pyrheliometers................................................................................................................................................................... 3
6.1.3 Total-ultraviolet radiometers................................................................................................................................ 4
6.1.4 Narrow-band ultraviolet radiometers............................................................................................................ 4
6.2 Other climate-measuring instruments................................................................................................................................ 4
7 Test specimens........................................................................................................................................................................................................ 4
8 Procedure..................................................................................................................................................................................................................... 5
9 Supplementary test conditions.............................................................................................................................................................. 5
10 ​Evaluation of properties................................................................................................................................................................................ 6
11
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Precision........................................................................................................................................................................................................................ 6
12 (standards.iteh.ai)
Test report.................................................................................................................................................................................................................... 6
Annex A (normative) Environment and climate ........................................................................................................................................ 8
ISO 2810:2020
Annex B (informative) Classification of climates...................................................................................................................................10
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Bibliography.............................................................................................................................................................................................................................. 12

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ISO 2810:2020(E)


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 has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely 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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www​.iso​.org/​patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
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World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www​.iso​.org/​
iso/​foreword​.html. (standards.iteh.ai)
This document was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee
SC 9, General test methods for paints and varnishes, ISOin2810:2020
collaboration with the European Committee for
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Standardization (CEN) Technical Committee CEN/TC 139, Paints and varnishes, in accordance with the
Agreement on technical cooperation between bcb853a24b3b/iso-2810-2020
ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 2810:2004), which has been technically
revised. The main changes compared to the previous edition are as follows:
— in Clause 4, the list in b) has been amended by radiant exposure and temperature;
— the time of wetness has been deleted from the list of additional observations on climate in A.2 and
replaced by a note with the reference to ASTM Practice G84;
— the climate classification in Annex B has been updated to ISO 877-1:2009;
— the text has been editorially revised and the normative references have been updated.
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.

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INTERNATIONAL STANDARD ISO 2810:2020(E)

Paints and varnishes — Natural weathering of coatings —

Exposure and assessment

1 Scope
This document specifies the conditions to take into consideration when selecting the type of natural
weathering and the natural weathering procedure to determine the resistance of coatings or coating
systems (direct weathering or weathering behind window glass).
Natural weathering is used to determine the resistance of coatings or coating systems (denoted in this
document by coatings) to the sun's radiation and the atmosphere.
This document does not take into account special atmospheric influences, e.g. industrial pollution.

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.
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ISO 1514, Paints and varnishes — Standard panels for testing
ISO 2808, Paints and varnishes —(standards.iteh.ai)
Determination of film thickness
ISO 4618, Paints and varnishes — Terms and ISOdefinitions
2810:2020
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WMO Publication No, 8, Guide to bcb853a24b3b/iso-2810-2020
meteorological instruments and methods of observation, World
Meteorological Organization, Geneva, 2012

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 4618 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://​w ww​.iso​.org/​obp
— IEC Electropedia: available at http://​w ww​.electropedia​.org/​
3.1
durability
ability of a specimen to resist the deleterious effect of its environment
3.2
time of wetness
period during which an exposed coating has surface moisture present on it

4 General
The durability of a coating during natural weathering depends on how, where and when the coating is
weathered. Therefore, these parameters and the intended use of the coating shall be taken into account
when exposures are carried out.

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In particular, the following parameters shall be considered:

a) the location of the exposure site, for example industrial, marine, rural; in choosing sites, those
which differ markedly in the type or level of pollution from the normal shall be avoided, unless they
are appropriate to the intended end use of the coating under test;
b) the height, angle and orientation of the exposure rack; these parameters govern the extent to
which the specimens are affected, for example by radiant exposure, temperature, dew, frost and
atmospheric pollutants;
c) the nature of the terrain on which the rack is constructed (for example concrete, grass, gravel);
the terrain may affect the climatic conditions around the specimen under test; it would rarely be
feasible to select an ideal terrain in practice, but the effect of such variations in climatic conditions
will be minimized by ensuring that all specimens are situated sufficiently high above the ground
(see Clause 5);
d) whether the performance of the coating on the front and/or the back of the specimen is of interest;
certain types of degradation, for example rust formation and/or mould growth, are frequently
more severe on the shaded parts of the specimen;
e) the intended use of the coating, including its substrate, and whether the coating is to be washed or
polished in service.
The results of tests on an exposure rack apply precisely only to the environment in which they were
obtained.
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Provided that the test conditions are reasonably appropriate to the intended end use, the relative
performance of a number of coatings tested at the same time enables valid deductions to be drawn. It is
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recommended that each series of specimens under evaluation include coatings of known performance
to act as reference standards.
ISO 2810:2020
The results of natural weathering may vary according to the time of year during which the tests are
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carried out. The influence of these variations is reduced if the exposure period is sufficiently long. The
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exposure period should be at least one year, or a multiple of one year. The reproducibility of the results
is improved if the exposure period always starts at the same time of year, preferably in spring.
Natural weathering tests are normally carried out for a fixed period of time. However, in many cases
it is preferable to define the test period in terms of a certain degree of degradation or by the radiant
exposure (dosage) of solar radiation to which the specimen is to be subjected (see Clause 6). The latter
procedure can reduce the influence of seasonal variations but does not eliminate it.
Radiant exposure can be determined by measurement of irradiance, and integration of the
measurements over the period of natural weathering.
The climatic conditions shall be monitored, and a complete record shall be reported, together with the
other conditions of weathering.
Care is required in the selection of test specimens of substrates with variable (anisotropic) properties,
for example wood or steel. In these cases, replication of the tests is essential to avoid misleading results.
Washing and polishing during exposure affects the durability of the coating. It shall therefore be
mentioned in the test report.

5 Exposure racks
Unless otherwise specified or agreed, use exposure racks on which the specimens are facing towards
the equator. The specimens shall be firmly held on the racks by attachments made of stainless steel or
other corrosion-resistant material, in such a manner that they are mechanically stressed as little as
possible.

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The exposure racks shall be constructed so that the atmosphere has free access to the specimens and
that water that drains from one specimen does not drain onto another. In addition, the racks can be
designed so that a portion of the specimens can be covered to allow evaluation between an exposed and
a masked area. By using special devices, particular conditions may be simulated, for example by using a
“black box” in accordance with SAE J 1976 to simulate automotive conditions or backing the test panel
with plywood or other insulation material to simulate building side wall or roof area conditions.
Metal substrates for corrosion tests shall not be in electrical contact with metals during the exposure
period or, as far as possible, in direct contact with wood or other porous materials. If specimens are
supported in grooves, suitable drainage holes shall be provided to prevent accumulation of water.
Unless otherwise stated, the racks shall be constructed so that all specimens are supported either at a
minimum height of 0,45 m above the ground or at a height sufficient to avoid contact with vegetation
and to prevent damage.
The area beneath and in the vicinity of the racks shall be characterized by low reflectance and by
ground cover typical of that climatological area. In desert areas, the racks shall be located on gravel, in
most temperate areas on low-cut grass.
Usually the panels are supported at an angle of 45° to the horizontal. Depending on the intended end
use of the coating, other angles may be agreed, for example 5° for automotive finishes or roof coatings,
or vertical exposure for textured wall finishes.
NOTE When testing corrosion performance, it is appropriate to expose specimens vertically facing away
from the equator as well as inclined at 45° and 5° facing towards the equator (see EN 13523-19).
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Specimens facing away from the equator will remain wet for longer periods since they dry less rapidly
than those exposed facing towards the equator. This leads to a higher tendency to corrode.
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The racks shall be situated so that, at a sun height of 20° and more, no shadow falls on to the specimens.
ISO 2810:2020
When testing the durability of coatings for interior use which are exposed to radiation which has
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passed through window glass, racks that are covered by a window pane are used. Since, depending
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on the quality, the transmission of window glass in the UV range is different, the type of window glass
shall be agreed upon between the interested parties for each particular case (see Clause 9).

6 Apparatus for measurement of climatic factors

6.1 Measurement of solar radiation

6.1.1 Pyranometers

Pyranometers are radiometers used to measure the total solar radiant energy incident upon a surface
per unit time per unit area.
The energy measured includes direct and diffuse radiant energy as well as radiant energy reflected
from the background.
Pyranometers shall meet at least the requirements for a second class instrument as defined by the
World Meteorological Organization (WMO), WMO Publication No. 8. In addition, pyranometers shall
be calibrated at least annually, and their calibration factor shall be traceable to the World Radiometric
Reference (WRR) WMO Publication No. 8, Chapter 9.

6.1.2 Pyrheliometers

Pyrheliometers are radiometers used to measure the direct (beam) solar irradiance incident on a
surface normal to the sun's rays.

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The energy measured excludes diffuse radiant energy as well as radiant energy reflected from the
background.
Pyrheliometers shall meet at least the requirements for a first class instrument as defined by the WMO
Publication No. 8. In addition, pyrheliometers shall be calibrated at least annually, and their calibration
factor shall be traceable to the WRR WMO Publication No. 8.

6.1.3 Total-ultraviolet radiometers

When used to define exposure stages, total-ultraviolet radiometers shall have a passband that
maximizes the acceptance of radiation in the 300 nm to 400 nm, 295 nm to 385 nm, or any other
commonly used total-ultraviolet wavelength region, and they shall be cosine-corrected to include
ultraviolet sky radiation. Commercially available total-ultraviolet radiometers require annual
calibration checks if they are deployed between latitudes 40° north and 40° south. Outside these
latitudes, annual calibration is not a requirement but it is considered good practice.

6.1.4 Narrow-band ultraviolet radiometers

When used to define exposure stages, narrow-band ultraviolet radiometers shall be cosine-corrected if
used in conjunction with either natural fixed-angle or glass-filtered exposures. They shall be calibrated
following the manufacturer’s instructions.

6.2 Other climate-measuring instruments

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Instrumentation required for the measurement of air temperature, specimen surface temperature,
relative humidity, rainfall, time of wetness, and sunshine hours shall be appropriate to the exposure
(standards.iteh.ai)
method used and shall be agreed upon between the interested parties.

ISO 2810:2020
7 Test specimens https://standards.iteh.ai/catalog/standards/sist/a175498d-febc-4ec2-bab2-
The simplest and most widely used test specimen bcb853a24b3b/iso-2810-2020
is a flat panel of the appropriate substrate, but much
useful additional information can be obtained by carrying out exposure tests on structures. This is
particularly true of wooden assemblies such as window frames, where coating performance at the
joints is of interest. Design features which allow accumulation and entrapment of water can also lead
to premature coating degradation. Therefore, test specimens should preferably be included which show
the characteristics of such structures.
Unless otherwise agreed, use standard test panels in accordance with ISO 1514, with the area of the
panels at least 0,03 m2 and no side less than 100 mm long.
Coat the panels with the product(s) under test by the appropriate method and dry (or stove) each coat
in the specified manner for the specified time, followed (if appropriate) by conditioning or ageing. Coat
both faces and the edges of the panels with the product under test, unless the panel would not be used
in such manner. Alternatively, the back and edges may be coated with a good-quality protective paint
[see Clause 4, d)].
If specified or agreed, particularly in the case of corrosion tests, provide uncoated areas on the
specimen, preferably by one or more of the following methods.
a) After the specified drying time and immediately before placing the specimens on the exposure
rack, make a straight scratch or scribe mark through the coating to the substrate. To make the
scratch, use an instrument with a hard tip. The scratch shall have a width of 0,2 mm to 1,0 mm,
unless otherwise agreed. As the result of the test depends on, e.g. the depth of the scratch and the
scratching tool used, the details of how the scratch was made shall be stated in the test report.
NOTE Normally, vertical and/or horizontal lines are used. By agreement, diagonal criss-cross lines (a
St. Andrew's cross) can be employed. However, in this case, the coating might flake where the lines cross
which makes evaluation, e.g. by image analysis, difficult.

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b) Before applying the product(s) under test, attach to the prepared specimen a strip of pressure-
sensitive adhesive tape of agreed size at an agreed location. Coat the specimen in the normal way.
Either directly after coating or immediately before placing on the exposure rack, carefully remove
the tape. Clean off any residues of adhesive with a suitable solvent which does not affect the coating.
Determine the thickness, in micrometres, of the coating by using one of the non-destructive methods
specified in ISO 2808. Provide the specimens with a suitable marking which is resistant to natural
weathering.
The number of test specimens depends on
— the number of different properties to be investigated and the number of specimens required for
each test method, and
— the number of times each test method is to be carried out before, during and after weathering.
If not otherwise specified or agreed, the number of test specimens shall be not less than three.
The use of reference specimens of known durability and of composition similar to that of the test
specimen is recommended.

8 Procedure
After any conditioning or specified pre-aging, expose the specimens on the rack for the specified time or
until the specified level of radiant exposure has been reached or until a defined degree of degradation
is reached. iTeh STANDARD PREVIEW
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If specified, wash all or part of the specimen at the required intervals. If only part of the specimen is to
be washed, it is preferable to wash a strip on the right or left of the specimen, rather than at the top or
bottom. It can also be necessary to define exactly the particular area to be washed. When the specimen-
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is not specified in detail, use water in accordance with ISO 3696, grade 3, to which
a suitable wetting agent has been added. Apply the washing solution with a soft brush or soft sponge,
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subsequently rinsing the surface thoroughly with water of grade 3, avoiding mechanical damage.
If specified, wash and polish all or part of each specimen at the required intervals, using the
specified polish.
Examine the specimens at defined intervals, separately noting the resistance of the coating on the front,
back, edges or bare areas. Examinations shall be at intervals appropriate to the rate of degradation, for
example for change of colour, for loss of gloss, for blistering of the coating and for signs of corrosion of
the substrate. If specified, also examine with ×10 magnification for cracking, blistering of the coating
and for signs of corrosion of the substrate. Examine for signs of chalking by pressing and rotating (or
wiping) a piece of velvet of contrasting colour over the surface, for example in accordance with the
method described in ISO 4628-7.
After the specified period of exposure, carry out a final examination of the coating. If it is required to
examine the substrate for signs of attack, remove the coating by the specified method.

9 Supplementary test conditions

For any particular application of the test method specified in this document, more details, in addition to
those in the preceding clauses, might be required.
To enable the method to be carried out, the following test conditions shall be laid down as appropriate:
a) the material, the thickness and the surface preparation of the substrate;
b) the method of application of the coating materials under test to the substrate;

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