GB/T 3181-2008Colour standard for paint film (English PDF)

3.1 Surface color

The surface color of an opaque object.

3.2 Achromatic color (neutral color)

The surface color of an object without spectral selectivity, a series of neutral grays from black to white.

3.3 Chromatic color

The color beyond the achromatic color.

3.4 White

Neutral color with object lightness greater than 8.5.

3.5 Black

Neutral color with object lightness less than 2.5.

3.6 Grey

Neutral color with object lightness between 2.5 and 8.5.

3.7 Absolute white

The ideal white with the object lightness of 10.

3.8 Absolute black

The ideal black with the object lightness of 0.

3.9 Complementary color

Two colors mixed in an appropriate ratio to generate the neutral color. For example, red and green, blue and yellow.

3.10 Gloss

The nature of the object surface of oriented selective reflection. It is the apparent perceptual nature of the object surface due to the spatial distribution of the reflected light; it is related to the size of the surface oriented reflective component and the […]

3.18 CIE standard illuminants

A specific relative spectral power distribution incident on an object as specified by CIE, including:

a) Standard illuminator A: a complete radiator with an absolute temperature of 2856K as specified by the international practical temperature scale.

b) Standard illuminator C: the average daylight with the correlated color temperature about 6774K.

c) Standard illuminator D65: average daylight with correlated color temperature about 6504K. Standard illuminator D55: daylight with correlated color temperature about 5503K. Standard illuminator D75: daylight with correlated color temperature about 7504K.

3.19 CIE standard sources

In order to realize the standard illuminators A, C, D65, etc.; the artificial light source specified by CIE.

3.20 Color temperature

When the chromaticity of the light source is the same as that of the complete radiator at a certain temperature, the absolute temperature of such complete radiator is the color temperature of the light source. The symbol of color temperature is Tc, in K.

3.21 Colorimeter

Instrument for measuring the color tristimulus values or chromaticity coordinates.

3.22 Visual filed

The solid angle range of the object being observed when the eye position is not moving.

3.23 Illuminating-viewing condition

The geometrical conditions among illumination source, object and observer. Such as 0/45 (vertical illumination/45° direction observation), d/8 (diffuse illumination/8° direction observation), 0/d (vertical illumination/diffuse observation), etc.

3.24 CIE 1931 standard colorimetric system

The colorimetric system represented by spectral tristimulus values of (lambda), (lambda), (lambda) specified by CIE 1931. measured according to the provisions of GB/T 3979; the test conditions are D65 light source, 10° visual filed, d/0 illumination observation condition.

6.1 Test template

6.1.1 Unless otherwise specified, the test template shall be the tinplate, hard aluminum plate, steel plate or glass plate specified in GB/T 9271. The plate surface shall be flat; the size shall be no less than 120mm × 50mm.

6.1.2 Unless otherwise specified, each test template shall be handled according to the provisions of GB/T 9271; then coat the test product as per the specified or agreed method, dry (or bake and maintain) each painted test template to the specified time.

NOTE: The paint film shall completely cover the substrate. For the paint film that can't cover the substrate completely, its color is affected by the color of the substrate and thickness of paint film (determined as per a method specified in GB/T 13452.2).

6.2 Colorimetry

6.2.1 Colorimetric method

The color shall be compared as per the provisions of GB/T 9761. Generally, the conventional method is used to visually compare the test template with color standard under the natural daylight or artificial light source. The colorimeter can also be used, directly measure the color difference (delta E) under the agreed light source (D65 light source or C light source), illumination observation conditions [45/0, 0/45, d/8(0) or 8(0)/d] and visual filed conditions (10° or 2°). […]

6.2.2 Light source