GB/T 6739-2022 English PDF (GBT6739-2022)

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GB/T 6739-2022: Paints and varnishes -- Determination of film hardness by pencil test
GB/T 6739-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 87.040
CCS G 50
Replacing GB/T 6739-2006
Paints and Varnishes – Determination of Film Hardness by
Pencil Test
(ISO 15184:2020, MOD)
ISSUED ON: DECEMBER 30, 2022
IMPLEMENTED ON: JULY 1, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative References ... 6
3 Terms and Definitions ... 7
4 Principle ... 7
5 Apparatus ... 7
6 Sample ... 9
7 Test Panel ... 10
8 Operation Procedure ... 10
9 Type of Defect ... 11
10 Precision ... 12
11 Test Report ... 12
Appendix A (Informative) Technical Differences and Causes between this Document
and ISO 15184:2020 ... 13
Appendix B (Informative) Applicability of Pencil Hardness Test ... 14
Foreword
This document was drafted as per the rules specified in GB/T 1.1-2020 Directives for
Standardization – Part 1: Rules for the Structure and Drafting of Standardizing Documents.
This Document replaced GB/T 6739-2006 Paints and Varnishes - Determination of Film
Hardness by Pencil Test. Compared with GB/T 6739-2006, the major technical changes of this
Document are as follows besides the structural adjustments and editorial modifications:
a) Change the “Scope” (see Clause 1 of this Edition; Clause 1 of the 2006 Edition);
b) Change the "Normative References" (see Clause 2 of this Edition; Clause 2 of the 2006
Edition);
c) Delete the relevant content of "definition of defects" in the definition of the term pencil
hardness (see Clause 3 of the 2006 Edition);
d) Change the “Principle” (see Clause 4 of this Edition; Clause 4 of the 2006 Edition);
e) Delete “Required supplementary information” (see Clause 5 of the 2006 Edition);
f) Change the load exerted by the pencil port on the surface of the paint film (see 5.1of this
Edition; 6.1 of the 2006 Edition); known applicable pencil models and manufacturers
(see 5.2 of this Edition; 6.2 of the 2006 Edition); and add relevant contents that can also
use the pencil lead in the pen holder (movable/automatic pencil) (see 5.2 of this Edition);
g) Delete the relevant content that can also use the drawing eraser to clean the template (see
6.5 of the 2006 Edition);
h) Change the "Operating Procedures" (see Clause 8 of this Edition; Clause 9 of the 2006
Edition);
i) Add "Defect Type" (see Clause 9 of this Edition);
j) Change "Precision" (see Clause 10 of this Editon; Clause 10 of the 2006 Edition);
k) Change the "Test Report" (see Clause 11 of this Edition; Clause 11 of the 2006 Edition);
l) Change the content of "Required Supplementary Information" (see Appendix B of this
Edition; Appendix A of the 2006 Edition).
This Document modified and adopted ISO 15184:2020 Paints and Varnishes - Determination
of Film Hardness by Pencil Test.
Compared with ISO 15184:2020, this Document made the following structural adjustments:
--- Appendix B corresponded to Appendix A in ISO 15184:2020.
Paints and Varnishes – Determination of Film Hardness by
Pencil Test
IMPORTANT TIPS: The electronic version of this Document contains color content that
is intended to assist in the correct understanding of this Document. Therefore, users
should consider using a color printer to print this Document.
1 Scope
This Document specifies a method for determining the hardness of paint films by pushing a
pencil of known hardness across the film.
This Document is applicable to the determination of the paint film hardness of a single coating
of paints, varnishes and related products; and is also applicable to the determination of the paint
film hardness of the top layer of a multi-coating.
This Document is not applicable to comparing the pencil hardness of different paint films. This
Document is applicable to providing a relative rating of a series of painted test panels with
significant differences in pencil hardness.
This Document is only applicable to the determination of paint film hardness on smooth
surfaces.
2 Normative References
The provisions in following documents become the essential provisions of this Document
through reference in this Document. For the dated documents, only the versions with the dates
indicated are applicable to this Document; for the undated documents, only the latest version
(including all the amendments) is applicable to this Document.
GB/T 3186 Paints varnishes and raw materials for paints and varnishes – Sampling (GB/T
3186-2006, ISO 15528:2000, IDT)
GB/T 9271 Paints and varnishes standard panels for testing (GB/T 9271-2008, ISO
1514:2004, MOD)
GB/T 13452.2 Paints and varnishes - Determination of film thickness (GB/T 13452.2-2008,
ISO 2808:2007, IDT)
GB/T 20777 Paints and varnishes - Examination and preparation of samples for testing
(GB/T 20777-2006, ISO 1513:1992, IDT)
GB/T 37356 Paints and varnishes - Lighting and procedure for visual assessments of
coatings (GB/T 37356-2019, ISO 13076:2012, IDT)
ISO 4618 Paints and varnishes – Terms and definitions
NOTE: GB/T 5206-2015 Paints and varnishes – Terms and definitions (ISO 4618:2014, IDT)
3 Terms and Definitions
For the purposes of this Document, the following terms and definitions given in ISO 4618 apply.
ISO and IEC maintain terminology databases used for standardization work at:
--- ISO online browsing platform: available from https://www.iso.org/obp;
--- IEC Electrical Encyclopedia: Available from http://www.electropedia.org/.
3.1 Pencil hardness
The ability of a paint film surface to resist scratches or other defects when a pencil of specified
size, shape and pencil lead hardness is pushed across the paint film surface.
4 Principle
Use a pencil lead with a specified geometric shape to press down on the surface of the paint
film at an angle of 45° under a load of (7.35 ± 0.15) N; and measure the pencil hardness of the
paint film by pushing the pencil on the paint film. Gradually increase the pencil hardness until
visible defects appear on the surface of the paint film. The pencil hardness of the paint film is
expressed as the hardness of the hardest pencil that does not cause defects in the paint film.
5 Apparatus
5.1 The test instrument consists of a metal block with a wheel on each side, as shown in Figure
1. The used wheel shall not scratch the surface of the paint film during the measurement process.
In the middle of the metal block, there is a cylindrical hole inclined at an angle of (45±1)° for
holding a pencil.
With the help of the clamp, the pencil is fixed to the instrument and always remains in the same
position.
A level instrument is installed on the top of the instrument to ensure the level of the instrument
7 Test Panel
7.1 Substrate
Unless otherwise agreed, the substrate specified in GB/T 9271 shall be selected; and the same
type of material as that used in actual use shall be selected as much as possible. The substrate
should be flat and without deformation.
7.2 Shape and size
The shape and size of the test panel shall ensure that the test panel remains level during the test.
7.3 Treatment and coating
Unless otherwise agreed, each test panel shall be treated according to the provisions of GB/T
9271; and then coated with the tested product or system according to the prescribed method.
7.4 Drying and conditioning
Each painted test panel is dried (or baked) under the specified conditions and stand (if
applicable)...