GB/T 7048-2026 Colour black—Determination of chrominance English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS
CCS
National Standard of the People's Republic of China
GB/T 7048-2026
Colour black - Determination of chrominance
色素炭黑 色度的测定
Issue date: 2026-02-27 Implementation date: 2026-09-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative References
3 Terms and Definitions
4 Principle
5 Reagents or Materials
6 Apparatus
7 Sample
8 Test Conditions
9 Test Procedure
10 Test Data Processing
11 Precision
12 Test Report
Colour carbon black — Determination of colour
WARNING — Persons using this document should have practical experience in regular laboratory work. This document does not purport to address all safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health measures and to ensure compliance with the conditions specified by relevant national regulations.
1 Scope
This document describes the test methods for the determination of colour (blackness, lightness and hue) of colour carbon black.
This document applies to the determination of colour of colour carbon black.
2 Normative references
The contents of the following documents constitute essential provisions of this document through normative reference. For dated references, only the edition cited applies. For undated references, the latest edition (including all amendments) applies.
GB/T 3780.8 Carbon black — Part 8: Determination of heating loss
GB/T 7044 Colour carbon black
GB/T 8170 Rules for rounding off of numerical values and expression and judgement of limiting values
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 object colour
The colour of light reflected or transmitted by an object.
NOTE: See GB/T 3979. The quantitative representation methods for object colour and luminous body colour involve relevant standards of SAC/TC 120 and SAC/TC 224, respectively, both of which are based on the CIE standard system.
3.2 chrominance
A three dimensional quantitative representation of object colour based on ISO/CIE 11664 4.
NOTE: Chrominance is divided into lightness and hue.
3.3 lightness
A visual characteristic value representing the brightness of an object colour.
NOTE: Lightness, also known as "brightness", is graded with absolute white and absolute black as references and is one of the three attributes of colour. See Annex A and GB/T 15608. It is represented by the coordinate L* in the three dimensional CIE 1976 colour space. The larger the value, the brighter the colour and the closer to white; the smaller the value, the darker the colour and the closer to black.
3.4 hue
A visual characteristic value representing the type of object colour, such as red, yellow, green, blue, purple, etc.
NOTE: Hue, also known as "tone", is one of the three attributes of colour. See Annex A and GB/T 15608. It is represented by the coordinates a* and b* in the three dimensional CIE 1976 colour space. a* represents the hue shift from red to green: a positive value indicates a reddish colour, and a negative value indicates a greenish colour. b* represents the hue shift from yellow to blue: a positive value indicates a yellowish colour, and a negative value indicates a bluish colour.
3.5 ink film
A stable ink paste film obtained by mixing an appropriate proportion of carbon black with linseed oil according to a specified procedure, followed by grinding and film formation.
3.6 reflectivity of light
The percentage ratio of the intensity of reflected light to that of incident light.
3.7 blackness
carbon black blackness
The value equal to 50 times the ratio of the light reflectivity of the ink film prepared from the carbon black and refined linseed oil to that of the ink film prepared from the standard reference carbon black and refined linseed oil, after both have been mixed, ground and formed into ink films.
4 Principle
4.1 The colour carbon black test sample (hereinafter referred to as "test sample") and the reference carbon black SRB3# or IRC4# (hereinafter referred to as "reference sample") are each mixed with refined linseed oil and ground to obtain a uniform ink paste, which is then coated to form an ink film.
4.2 The light reflectivity of the ink film of the test sample and that of the reference sample are measured separately using a light reflectometer or a spectrophotometer. The blackness value of the test sample is represented by 50 times the ratio of the light reflectivity of the test sample ink film to that of the reference sample ink film.
4.3 The coordinate values L, a, b* in the three dimensional CIE 1976 L*a*b* colour space of the ink film are measured using a spectrophotometer, where L* represents the lightness of the test sample, and a* and b* represent the hue of the test sample.
5 Reagents or materials
5.1 Ethanol (CAS: 64 17 5), chemically pure (95%).
5.2 Refined linseed oil: dynamic viscosity (20 °C): 4.0 Pa·s to 5.0 Pa·s; acid value (as KOH): < 10 mg/g; colour (iron cobalt method): < No. 10.
5.3 Reference carbon black SRB3# or IRC4#.
.4 Absorbent cotton or soft thin paper, absorbent, lint free.
5.5 Sulphuric acid paper or glassine paper (for wrapping ink paste).
6 Apparatus
6.1 Analytical balance: actual scale interval d = 0.1 mg.
6.2 Automatic flat grinding mill: adjustable pressure not less than 0.017 MPa, ground glass surface, with an automatic counter.
6.3 Light reflectometer: measuring range 0 to 199.9, resolution 0.1.
6.4 Spectrophotometer: suitable for the ISO/CIE 11664 4 standard system, 45/0 optical geometry, accuracy 0.5%.
6.5 Oven: gravity convection type, capable of controlling the temperature at (125 ± 2) °C.
6.6 Syringe: accuracy 0.1 mL.
6.7 Desiccator: containing an effective desiccant.
6.8 Ink mixing knife: flexible, made of stainless steel, tapered, length 100 mm to 150 mm.
6.9 Ink film applicator: groove depth: 0.07 mm to 0.10 mm, capable of producing an ink film with uniform thickness and a flat surface (see Figure 1).
6.10 Glass plate.
7 Sample
Sampling shall be carried out in accordance with GB/T 7044.
Standard
GB/T 7048-2026 Colour black—Determination of chrominance (English Version)
GB/T 7048-2026 Colour black—Determination of chrominance English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS
CCS
National Standard of the People's Republic of China
GB/T 7048-2026
Colour black - Determination of chrominance
色素炭黑 色度的测定
Issue date: 2026-02-27 Implementation date: 2026-09-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative References
3 Terms and Definitions
4 Principle
5 Reagents or Materials
6 Apparatus
7 Sample
8 Test Conditions
9 Test Procedure
10 Test Data Processing
11 Precision
12 Test Report
Colour carbon black — Determination of colour
WARNING — Persons using this document should have practical experience in regular laboratory work. This document does not purport to address all safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health measures and to ensure compliance with the conditions specified by relevant national regulations.
1 Scope
This document describes the test methods for the determination of colour (blackness, lightness and hue) of colour carbon black.
This document applies to the determination of colour of colour carbon black.
2 Normative references
The contents of the following documents constitute essential provisions of this document through normative reference. For dated references, only the edition cited applies. For undated references, the latest edition (including all amendments) applies.
GB/T 3780.8 Carbon black — Part 8: Determination of heating loss
GB/T 7044 Colour carbon black
GB/T 8170 Rules for rounding off of numerical values and expression and judgement of limiting values
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 object colour
The colour of light reflected or transmitted by an object.
NOTE: See GB/T 3979. The quantitative representation methods for object colour and luminous body colour involve relevant standards of SAC/TC 120 and SAC/TC 224, respectively, both of which are based on the CIE standard system.
3.2 chrominance
A three dimensional quantitative representation of object colour based on ISO/CIE 11664 4.
NOTE: Chrominance is divided into lightness and hue.
3.3 lightness
A visual characteristic value representing the brightness of an object colour.
NOTE: Lightness, also known as "brightness", is graded with absolute white and absolute black as references and is one of the three attributes of colour. See Annex A and GB/T 15608. It is represented by the coordinate L* in the three dimensional CIE 1976 colour space. The larger the value, the brighter the colour and the closer to white; the smaller the value, the darker the colour and the closer to black.
3.4 hue
A visual characteristic value representing the type of object colour, such as red, yellow, green, blue, purple, etc.
NOTE: Hue, also known as "tone", is one of the three attributes of colour. See Annex A and GB/T 15608. It is represented by the coordinates a* and b* in the three dimensional CIE 1976 colour space. a* represents the hue shift from red to green: a positive value indicates a reddish colour, and a negative value indicates a greenish colour. b* represents the hue shift from yellow to blue: a positive value indicates a yellowish colour, and a negative value indicates a bluish colour.
3.5 ink film
A stable ink paste film obtained by mixing an appropriate proportion of carbon black with linseed oil according to a specified procedure, followed by grinding and film formation.
3.6 reflectivity of light
The percentage ratio of the intensity of reflected light to that of incident light.
3.7 blackness
carbon black blackness
The value equal to 50 times the ratio of the light reflectivity of the ink film prepared from the carbon black and refined linseed oil to that of the ink film prepared from the standard reference carbon black and refined linseed oil, after both have been mixed, ground and formed into ink films.
4 Principle
4.1 The colour carbon black test sample (hereinafter referred to as "test sample") and the reference carbon black SRB3# or IRC4# (hereinafter referred to as "reference sample") are each mixed with refined linseed oil and ground to obtain a uniform ink paste, which is then coated to form an ink film.
4.2 The light reflectivity of the ink film of the test sample and that of the reference sample are measured separately using a light reflectometer or a spectrophotometer. The blackness value of the test sample is represented by 50 times the ratio of the light reflectivity of the test sample ink film to that of the reference sample ink film.
4.3 The coordinate values L, a, b* in the three dimensional CIE 1976 L*a*b* colour space of the ink film are measured using a spectrophotometer, where L* represents the lightness of the test sample, and a* and b* represent the hue of the test sample.
5 Reagents or materials
5.1 Ethanol (CAS: 64 17 5), chemically pure (95%).
5.2 Refined linseed oil: dynamic viscosity (20 °C): 4.0 Pa·s to 5.0 Pa·s; acid value (as KOH): < 10 mg/g; colour (iron cobalt method): < No. 10.
5.3 Reference carbon black SRB3# or IRC4#.
.4 Absorbent cotton or soft thin paper, absorbent, lint free.
5.5 Sulphuric acid paper or glassine paper (for wrapping ink paste).
6 Apparatus
6.1 Analytical balance: actual scale interval d = 0.1 mg.
6.2 Automatic flat grinding mill: adjustable pressure not less than 0.017 MPa, ground glass surface, with an automatic counter.
6.3 Light reflectometer: measuring range 0 to 199.9, resolution 0.1.
6.4 Spectrophotometer: suitable for the ISO/CIE 11664 4 standard system, 45/0 optical geometry, accuracy 0.5%.
6.5 Oven: gravity convection type, capable of controlling the temperature at (125 ± 2) °C.
6.6 Syringe: accuracy 0.1 mL.
6.7 Desiccator: containing an effective desiccant.
6.8 Ink mixing knife: flexible, made of stainless steel, tapered, length 100 mm to 150 mm.
6.9 Ink film applicator: groove depth: 0.07 mm to 0.10 mm, capable of producing an ink film with uniform thickness and a flat surface (see Figure 1).
6.10 Glass plate.
7 Sample
Sampling shall be carried out in accordance with GB/T 7044.
