ISO 19252:2025

International
Standard
ISO 19252
Second edition
Plastics — Determination of scratch
2025-05
properties
Plastiques — Détermination du comportement à la rayure
Reference number
© ISO 2025
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Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 5
5 Apparatus . 5
5.1 Test machine .5
5.1.1 General .5
5.1.2 Frame .5
5.1.3 Scratch tip.5
5.1.4 Test load .5
5.1.5 Test speed .6
5.1.6 Test specimen support .6
5.1.7 Force indicator .6
5.1.8 Scratch-tip displacement gauge .6
5.2 Instruments for measuring the test specimen dimensions .6
5.3 Monitoring and inspection devices (optional) .6
5.3.1 Monitoring device.6
5.3.2 Scratch inspection device .6
6 Test specimens . 7
6.1 Shape and dimensions .7
6.2 Preparation .7
6.2.1 Moulding .7
6.2.2 Inspection of specimens and measurement of specimen dimensions.7
6.3 Number of test specimens .7
6.4 Conditioning.7
7 Procedure . 8
7.1 Test atmosphere .8
7.2 Scratch test .8
7.2.1 General .8
7.2.2 Scratch tip.8
7.2.3 Test load .8
7.2.4 Test speed .9
7.2.5 Test direction.10
7.2.6 Clamping .10
7.2.7 Testing .10
7.2.8 Recording of data .10
7.2.9 Monitoring of scratch behaviour and inspection of the scratched surface
(optional) .10
8 Expression of results .11
8.1 General .11
8.2 Determination of type of scratch behaviour .11
8.3 Creation of scratch map .11
8.4 Determination of critical normal load . 12
9 Test report . 14
Annex A (informative) Photographic illustrations of different types of scratch behaviour .16
Annex B (informative) Example of a test machine . 17
Bibliography .18

iii
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
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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
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Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 2, Mechanical
behaviour.
This second edition cancels and replaces the first edition (ISO 19252:2008), which has been technically
revised.
The main changes are as follows:
— the Scope has been updated to specify materials suitable for use with the test method defined in this
document;
— the list of normative references (Clause 2) has been updated;
— the terms and definitions clause (Clause 3) has been updated;
— in 6.1, permission to use flat sample has been added.
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.

iv
International Standard ISO 19252:2025(en)
Plastics — Determination of scratch properties
1 Scope
This document specifies a method for determining the scratch properties of plastics under defined
conditions.
The method defined in this document is used to investigate the behaviour of specified types of specimens
under the scratch conditions defined and for classifying the type of scratch of specimens within the
limitations inherent in the test conditions. It can also be used to determine comparative data for different
types of material by means of a so-called scratch map in which the types of scratch behaviour for each set of
test conditions of test load and test speed are determined using the basic method of constant-load testing,
and also by means of the so-called critical normal load determined using an alternative method of linearly
increasing load testing.
The method is suitable for use with the following range of materials.
— thermoplastic moulding, extrusion and casting materials, including filled and reinforced compounds in
addition to unfilled types;
— thermosetting moulding materials, including filled and reinforced compounds;
— thermosetting sheets, rigid thermoplastic moulding and extrusion materials, including filled and
reinforced compounds in addition to unfilled types.
The method specifies the preferred dimensions for the test specimen and the preferred scratch-tip geometry.
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 291, Plastics — Standard atmospheres for conditioning and testing
ISO 294-1, Plastics — Injection moulding of test specimens of thermoplastic materials — Part 1: General
principles, and moulding of multipurpose and bar test specimens
ISO 10724-1, Plastics — Injection moulding of test specimens of thermosetting powder moulding compounds
(PMCs) — Part 1: General principles and moulding of multipurpose test specimens
ISO 20753, Plastics — Test specimens
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 https:// www .electropedia .org/

3.1
scratch
damage made by a hard instrument (scratch tip) when moved across a test specimen surface under specified
conditions of tip geometry, test load,P (3.2) and test speed, v (3.3)
Note 1 to entry: See Figure 1.
Key
P test load (N)
v test speed (mm/s)
R scratch tip radius (mm)
1 test specimen
2 scratch tip
Figure 1 — Schematic representation of a scratch
3.2
test load
P
force applied by the scratch tip perpendicularly to the test specimen during the test
Note 1 to entry: It is expressed in Newtons (N).
3.3
test speed
v
relative rate of displacement between the scratch tip and the test specimen during the test
Note 1 to entry: It is expressed in millimetres per second (mm/s).
3.4
scratch force
Fs
horizontal force between the scratch tip and the test specimen at any given moment during the test
Note 1 to entry: It is expressed in Newtons (N).

3.5
scratch-tip displacement
d
vertical displacement of the scratch tip relative to the test specimen surface at any given moment during the test
Note 1 to entry: It is expressed in micrometres (µm).
3.6
scratch distance
s
horizontal distance travelled by the scratch tip relative to the test specimen at any given moment during the test
Note 1 to entry: It is expressed in millimetres (mm).
3.7
scratch behaviour
type of deformation of the material under the action of the scratch tip
Note 1 to entry: Scratch behaviour is classified into three types: ploughing (p), wedge formation (w) and cutting (c), as
defined in 3.7.1 to 3.7.3.
Note 2 to entry: See Annex A
3.7.1
ploughing
p
scratch behaviour in which the scratch force, Fs (3.4) and scratch-tip displacement, d (3.5) are constant over
the scratch distance during the test
Note 1 to entry: See Figure 2, a) and Figure A.1 a).
Note 2 to entry: The surface of the scratch is smooth along its whole length rather than rough.
Note 3 to entry: A small, inherent level of episodic signal oscillation (of amplitude less than 3 N in the scratch force and
10 µm in the tip displacement) is acceptable.
3.7.2
wedge formation
w
scratch behaviour in which the scratch force, Fs (3.4) and/or scratch-tip displacement, d (3.5) oscillate,
resulting in a corresponding increase in the actual distance travelled by the scratch tip during the test
Note 1 to entry: See Figure 2, b) and Figure A.1 b).
Note 2 to entry: The surface of the scratch exhibits a continuous serrated or wedge-like pattern, and stick-slip occurs.
3.7.3
cutting
c
scratch behaviour in which the scratch force, Fs (3.4) and/or scratch-tip displacement, d (3.5) vary randomly,
resulting in a corresponding increase in the actual distance travelled by the scratch tip during the test
Note 1 to entry: See Figure 2, c) and Figure A.1 c).
Note 2 to entry: During the test, chips are cut from the surface.

a) Ploughing (p) b) Wedge formation (w) c) Cutting (c)
Key
X scratch distance, s (mm)
Y1
scratch force, F (N)
s
Y2 scratch-tip displacement, d (µm)
1 ploughing
The scratch force and scratch-tip displacement are constant over the whole scratch distance and the scratched
surface is smooth along the whole length of the scratch (see 3.7.1).
2 wedge formation
The scratch force and/or scratch-tip displacement oscillate as the scratch distance increases, the scratched surface
exhibits a continuous serrated or wedge-like pattern and stick-slip occurs (see 3.7.2).
3 cutting
The scratch force and/or scratch-tip displacement vary randomly as the scratch distance increases and chips are
produced (see 3.7.3).
Figure 2 — Typical scratch force/scratch distance diagram, scratch-tip displacement/scratch
distance diagram and photo of scratched surface for each type of scratch behaviour

3.8
critical normal load
P
c
minimum normal force at which wedge formation or cutting, whichever occurs first, takes place at a given
test speed
Note 1 to entry: It is calculated from the relationship given in Formula (1) and Formula (2).
Note 2 to entry: It is expressed in Newtons (N).
4 Principle
A standard test specimen is scratched by a hard tip which applies a load perpendicular to the test specimen
and moves lengthwise across the surface at a constant speed along the centreline of the test specimen.
During the scratch, the horizontal force between the scratch tip and the test specimen (the scratch force),
the vertical displacement of the scratch-tip (scratch-tip displacement) and the scratch distance are each
measured continuously and recorded. The scratch force/scratch distance and tip displacement/scratch
distance diagrams thus produced describe the scratch behaviour of the test specimen. Using the basic method
of constant-load testing, the type of scratch behaviour can be determined for a series of test conditions (load
and speed) and expressed as a so-called scratch map. Using an alternative method of linearly increasing load
testing, the critical normal load can be determined at a given test speed (see Table 1). Changes in slope and/
or spikes in the scratch force/scratch distance curve indicate transitions from one type of scratch behaviour
to another (e.g. from ploughing to wedge formation or to cutting).
5 Apparatus
5.1 Test machine
5.1.1 General
The test machine shall consist essentially of a frame with a specimen support, a scratch tip with its associated
fittings, and a device for applying the load (see Figure B.1 in Annex B), and shall meet the specifications
given in 5.1.2 to 5.1.8.
5.1.2 Frame
The frame of the machine shall be capable of being levelled and shall not be deformed by more than 3 µm
under the maximum load.
5.1.3 Scratch tip
The scratch tip shall be hardened to at least Rockwell HRC 64 hardness, shall be polished to a roughness of
less than 0,20 µm and shall not show any deformation or damage after a test.
The scratch tip shall be hemispherical in shape, with an outside radius R of 0,5 mm ± 0,025 mm.
NOTE Tips made from hardened and polished steel or tungsten carbide have been found to be satisfactory.
5.1.4 Test load
The machine shall be capable of maintaining the test load within a tolerance of ±1 %, for any test load chosen
as specified in 7.2.3, and shall be capable of applying the load perpendicular to the test specimen within a
tolerance of ±5°.
5.1.5 Test speed
The machine shall be capable of maintaining the test speed within a tolerance of
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