GB/T 6739-2022 in English

《GB/T 6739-2022色漆和清漆 铅笔法测定漆膜硬度》由TC5（全国涂料和颜料标准化技术委员会）归口，TC5SC7（全国涂料和颜料标准化技术委员会涂料产品及试验方法分会）执行，主管部门为中国石油和化学工业联合会。

Paints and varnishes — Determination of film hardness by pencil test

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1 Scope

This document specifies a method for determining the film hardness by pushing pencils of known hardness over the film.

This document is applicable to the determination of the film hardness of single coating of a paint, varnish or related product, or to the determination of the film hardness of the upper layer of a multi-coat system.

It has not been found to be useful in comparing the pencil hardness of different coatings. It is more useful in providing relative ratings for a series of coated panels exhibiting significant differences in pencil hardness.

This document is applicable only to the determination of the film hardness of smooth surfaces.

2 Normative references

The following referenced documents are indispensable for the application 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.

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 terms and definitions given in ISO 4618 and the following apply.

3.1
pencil hardness
resistance of the surface of a paint film to marking, or the formation of some other defect, as a result of the action of a pencil, with a lead of specified dimensions, shape and hardness, which is pushed across the surface

4 Principle

A pencil lead with a defined geometry is pushed over the paint surface at an angle of 45°, exerting a force of (7.35 ± 0.15) N on the surface. The hardness of the pencil lead is increased in steps until the surface of the coating is marked by visible defects. The test result is the highest hardness at which no marking occurs.

Foreword II
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Apparatus
6 Sampling
7 Test panels
8 Procedure
9 Types of defect
10 Precision
11 Test report
Annex A (Informative) Technical deviations between this document and ISO 15184:2020 and their justifications
Annex B (Informative) Applicability of the pencil hardness test