What lighting conditions are required for checking paint colour according to this standard?

The test should be conducted under diffuse natural daylight or artificial daylight that matches CIE standard illuminant D-65.

Which Indian Standard provides the reference colour cards used during this test?

IS 5 provides the standard colours for ready-mixed paints and enamels used for visual matching.

How should the test panel be held relative to the observer and light source?

It should be held such that it is illuminated at normal incidence and viewed at an angle of 45 degrees, or vice versa, at a distance of about 500 mm.

IS 101 Part 2/Sec 1

: 1986

Methods of sampling and test for paints, varnishes and related products: Part 2 Optical properties Section 1 Colour

CurrentSpecializedTesting MethodMaterials Science · Painting, Coatings and Surface Finishing

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This section of IS 101 specifies the testing procedures to evaluate the optical properties, specifically the colour, of paints and varnishes. Engineers and quality control inspectors use this code to determine whether a cured paint film visually matches a specified standard colour (typically from IS 5) under standardized lighting conditions.

Specifies methods for determining the colour of paints, varnishes, and related products by visual comparison and instrumental methods.

Quick Reference Values

Standard viewing angle for visual comparison45 degrees to the incident light

Standard viewing distanceApproximately 500 mm

Preferred artificial illuminantCIE Standard Illuminant D65

Practical Notes

Visual colour assessment should always be performed under standard daylight conditions or in a standardized colour matching cabinet (D65 light) to prevent metamerism.

Always ensure the paint film is completely dry before evaluating its final colour, as wet and dry paint colours often differ significantly.

Avoid direct glare during inspection by viewing the panel at an angle of 45 degrees rather than straight on.