BS 8493:2008+A1:2010

BS 8493 specifies the method of test to determine the Light Reflectance Value (LRV) of different surfaces of materials. LRV is the proportion of visible light reflected by a surface compared to the sensitivity to light of the human eye.

BS 8493 applies to:

• Opaque paint coatings and paint systems, including those that cause extreme angular dependences of reflected light and those that have a surface texture of <2 mm
• Opaque coverings including those that cause extreme angular dependences of reflected light, and those that have an unyielding texture of <2 mm
• Opaque coverings with a yielding pile, e.g. carpet
• Opaque materials, including those that cause extreme angular dependences of reflected light, and those that have a texture of <2 mm, e.g. finished metals
• Opaque materials coated with non-opaque coatings or coverings, e.g. timber door coated with a woodstain, including those that cause extreme angular dependences of reflected light, and those that have a texture of <2 mm
• Multi-coloured surfaces
• Ordinary materials.

The method of test is not suitable for the following surfaces:

• Thermochromic
• Photochromic
• Retroreflecting
• Fluorescent
• Phosphorescent
• Surfaces involving electrical power for light emission
• Self-luminous characteristics or for free-standing, non-opaque materials, e.g. glass and clear plastic for curved surfaces.

BS 8300 points out that the LRV between two visually adjacent surfaces can help to predict the ability of people who are visually impaired to see a difference. The greater the LRV difference between two visually adjacent surfaces, the more likely that the difference would be identified. Paint manufacturers therefore also need to cater for visually impaired people.

Contents:

• Foreword
• 1 Scope
• 2 Normative references
• 3 Terms and definitions
• 4 Principle
• 5 Apparatus
• 6 Preparation of test specimens
• 7 Procedure
• 8 Test
• 9 Expression of results
• 10 Test report
• Annexes
• Annex A (informative) Comparison between the BS colour code and the LRV of colours within BS 4800
• Bibliography