ISO 18951-2:2022
(Main)Imaging materials — Scratch resistance of photographic prints — Part 2: Sclerometer test method
Imaging materials — Scratch resistance of photographic prints — Part 2: Sclerometer test method
Matériaux pour l'image — Résistance à la rayure des épreuves photographiques — Partie 2: Méthode d'essai au scléromètre
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 18951-2
First edition
2022-11
Imaging materials — Scratch
resistance of photographic prints —
Part 2:
Sclerometer test method
Matériaux pour l'image — Résistance à la rayure des épreuves
photographiques —
Partie 2: Méthode d'essai au scléromètre
Reference number
ISO 18951-2:2022(E)
© ISO 2022
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ISO 18951-2:2022(E)
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© ISO 2022
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ISO 18951-2:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
4.1 General . 1
4.2 Constant load . 2
5 Test device . 2
5.1 Test device description . 2
5.2 Selection of stylus . 3
6 Samples . 4
6.1 General . 4
6.2 Test target . 4
6.3 Preparation . 4
6.4 Conditioning. 4
7 Test procedure .5
7.1 General . 5
7.2 Testing conditions . 5
7.3 Constant load . 5
8 Evaluation . 6
8.1 General . 6
8.2 Visual evaluation of surface deformation . 6
8.3 Scratch susceptibility . 6
9 Test report . 7
Bibliography . 8
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ISO 18951-2:2022(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
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 42, Photography.
A list of all parts in the ISO 18951 series can be found on the ISO website.
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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ISO 18951-2:2022(E)
Introduction
This method is one of a series ISO 189xx relating to permanence and durability of image prints, which
is their resistance to mechanical, chemical and/or environmental stresses in conditions of use. The
permanence of the image under environmental stresses is tested by each stress factor individually:
[6] [5] [7] [8]
light (ISO 18937 ), heat (ISO 18936 ), ozone (ISO 18941 ), and humidity (ISO 18946 ). These
stress factors are given by the ambient conditions, over which the user often has limited control. The
exposure to mechanical and physical stress may often be controlled by the user, unless intense handling
is integral to intended use. Tests for rubbing of prints resulting in abrasion or smearing of the image are
[9] [10] [3]
handled in ISO 18947-1 and ISO 18947-2 , scratch resistance (of film) is addressed in ISO 18922
[4]
and durability tests to simulate accidental exposure to water are described ISO 18935 .
Photographic prints are also susceptible to scratching when handled. This problem is particularly
evident with digital prints, which may be composed of various layers and may include colorants on the
surface that are not protected from physical damage. Test methods for evaluating the scratch resistance
of photographic prints are another means to characterise the physical durability of photographic prints.
This document provides standardized requirements to evaluate the scratch resistance of image prints
in their various formats. Scratch might occur accidentally or repeatedly by handling of the image. The
following are some examples of sources of scratching:
— fingernails;
— sharp edge of metallic or mineral object (e.g. accessories such as rings);
— improper cleaning.
Test devices for scratch tests allow a wide variety of test conditions and parameters. Therefore, the
test method and test conditions should be carefully determined considering the print material and its
expected use.
Scratching tends to occur in a specific location at a single point of contact, as opposed to abrasion which
affects larger areas of the print material.
There is no general correlation between damage to digital prints from abrasion and from scratches.
For example, some inkjet prints show both abrasion and scratch damage, while other inkjet prints
are damaged from scratches but not abrasion. Similarly, some digital press samples are damaged by
[14]
abrasion, but not from scratches .
All types of digital prints may benefit from additional protection against abrasion and scratches.
Polyester or polyethylene sleeves and laminates, including liquid, thermal, and pressure-sensitive
materials, can provide this additional protection. Eliminating contact with adjacent surfaces, which
is achieved with window-matted prints, is also effective in preventing damage from abrasion and
[5]
scratches .
[2]
As a test method for scratching, the pencil test is well-known . However, it was determined to be
insufficient for photographic prints through round-robin testing in this committee because scratch
resistance of photographic prints has wider variety than the scale of pencil hardness. The pencil test
also proved difficult to carry out in a reproducible manner with photographic prints.
[13]
The sclerometer is also used extensively in determining the scratch resistance of paints and
[1][12]
varnishes .
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INTERNATIONAL STANDARD ISO 18951-2:2022(E)
Imaging materials — Scratch resistance of photographic
prints —
Part 2:
Sclerometer test method
1 Scope
This document specifies test parameters, test procedures, test targets, and reporting requirements
for determining the scratch resistance of photographic prints using the sclerometer test method. It
is applicable to photographic prints that have no protection as well as photographic prints that are
protected by a coating or lamination. It is specifically useful as a low-cost, easily implemented procedure
for evaluating scratch resistance of these prints.
It is not the purpose of this document to define limits of acceptability or failure. Limits would be
determined by the user and the intended application.
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 18913, Imaging materials — Permanence — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 18913 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:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
sclerometer
handheld, pen-like instrument used to determine scratch susceptibility of a material by drawing a
tungsten carbide tip across the material at a specified force
Note 1 to entry: The shape and size of the tungsten carbide tip, as well as its angle towards the surface under test,
affects the severity of scratching for a given force. The force is adjusted by means of a compressed spring in the
pen-like instrument.
4 Principle
4.1 General
Scratch resistance is a desirable property of prints and substrates. The degree to which it is required
depends on the intended applications of the photographic print.
1
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ISO 18951-2:2022(E)
The scratch test for the print is applied using a stylus which moves relative to the print with a specific
force. The vertical load on the stylus may cause a surface indentation. When the stylus moves along the
surface, the friction induces compressive/tensile/shear stress and deformation in the print surface. It
can cause deformation and damage at four different levels:
Level 0: No damage observed.
Level 1: Plastic deformation of the surface which forms a dent or line of indentation as pressure line or
changes to the surface gloss without cohesive failure of the coating
...
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