GB/T 30789.1-2015Paints and varnishes -- Evaluation of degradation of coatings -- Designation of quantity and size of defects, and of intensity of uniform changes in appearance -- Part 1: General introduction and designation system (English PDF)
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Issued by
General Administration of Quality Supervision, Inspection and Quarantine
Level / Type
National · Recommended
Issue date
June 2, 2015
Implementation date
January 1, 2016
Scope
GB/T 30789.1-2015 (Paints and varnishes -- Evaluation of degradation of coatings -- Designation of quantity and size of defects, and of intensity of uniform changes in appearance -- Part 1: General introduction and designation system) is available as an English-translated PDF.
GB/T 30789.1-2015 is the Chinese standard "Paints and varnishes -- Evaluation of degradation of coatings -- Designation of quantity and size of defects, and of intensity of uniform changes in appearance -- Part 1: General introduction and designation system".
Its scope clause reads: This Part of GB/T 30789 defines a system for designating the quantity and size of defects and the intensity of changes in appearance of coatings and outlines the general principles of the system used throughout GB/T 30789.
This system is intended to be used, in particular, for defects caused by ageing and weathering, and for uniform changes such as colour changes, for example yellowing.
The other parts of GB/T 30789 provide pictorial standards or other means of evaluating particular types of defect. As far as possible, already existing evaluation schemes have been used as the basis.
This Part of GB/T 30789 can also be used for assessing defects not covered by the other parts of GB/T 30789. Its clauses include general principles of the designation system.
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Document preview — GB/T 30789.1-2015
National Standard of the People's Republic of China
- ICS
- 87.040
- Classification
- G 50
Issued by: General Administration of Quality Supervision, Inspection and Quarantine
Contents
- Foreword3
- 1 Scope5
- 2 General principles of the designation system5
- 3 Assessment of defects and of intensity of changes6
- 4 Expression of results7
- 5 Test report8
1 Scope
This Part of GB/T 30789 defines a system for designating the quantity and size of defects and the intensity of changes in appearance of coatings and outlines the general principles of the system used throughout GB/T 30789. This system is intended to be used, in particular, for defects caused by ageing and weathering, and for uniform changes such as colour changes, for example yellowing.
The other parts of GB/T 30789 provide pictorial standards or other means of evaluating particular types of defect. As far as possible, already existing evaluation schemes have been used as the basis.
This Part of GB/T 30789 can also be used for assessing defects not covered by the other parts of GB/T 30789.
2 General principles of the designation system
A uniform convention has been adopted for designating the quantity and size of defects and the intensity of changes by means of ratings on a numerical scale ranging from 0 to 5.0 denoting no defects or changes, and 5 denoting defects or changes so severe that further discrimination is not reasonable. The other ratings, corresponding to the numbers 1, 2, 3 and 4, are so defined that they give optimum discrimination over the whole range of the scale.
The use of intermediate half-steps is permissible, if specified, to give a more detailed report on the defects or changes observed.
NOTE 1 The quantity of small defects scattered over the test area may be assessed by means of a grid method. Details of such a method are described in ISO 4540, Metallic coatings - Coatings cathodic to the substrate - Rating of electroplated test specimens subjected to corrosion tests.
NOTE 2 The GB/T 30789 ranking may be different from the ranking schemes used in
GB/T 30789.4-2015 | GB/T 30790.2-2014 | GB/T 30790.1-2014 | GB/T 30789.8-2015 | […]
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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 8 pages — is available in the English PDF.
Referenced standards
Cited by
- GB/T 20853-2026Corrosion of metals and alloys - Corrosion in artificial atmosphere - Accelerated corrosion test involving exposure under controlled conditions of humidity cycling and intermitted spraying of a salt solution
- GB/T 41954-2022Paints and varnishes - On-site test methods on quality assessment for interior wall coatings
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Related Standards
GB/T 30789.2-2014 — Paints and varnishes -- Evaluation of degradation of coatings -- Designation of quantity and size of defects, and of intensity of uniform changes in appearance -- Part 2: Assessment of degree of blistering
GB/T 30789.3-2014 — Paints and varnishes—Evaluation of degradation of coatings—Designation of quantity and size of defects,and of intensity of uniform changes in appearance—Part 3:Assessment of degree of rusting
GB/T 30789.4-2015 — Paints and varnishes -- Evaluation of degradation of coatings -- Designation of quantity and size of defects, and of intensity of uniform changes in appearance -- Part 4: Assessment of degree of cracking
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