BS 8493:2008+A1:2010

This standard BS 8493:2008+A1:2010 Light reflectance value (LRV) of a surface. Method of test is classified in these ICS categories:

• 11.040.70 Ophthalmic equipment

This British Standard specifies the method of test to determine the Light Reflectance Value (LRV) of different surfaces of materials, including preparation of representative specimens of surfaces of materials in standardized conditions.

The method of test is applicable 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.

NOTE 1 The results of the measurements could then be published as complying with the measurement method described in this standard.

The method described in this standard is not appropriate for making on-site measurements.

Therefore it is recommended that published LRV data, determined in accordance with this standard, are used for the determination of visual contrast.

NOTE 2 See BS 8300 which offers guidance on the application of LRV to provide an inclusive environment.

For opaque paint coatings and systems the LRV values are valid for coatings and systems, whatever the optical nature of the substrate, to which they are applied as long as the specified number of coats are applied at the specified spreading rate.

For opaque coverings, the LRV values determined by the use of this standard are valid for those coatings and systems whatever the optical nature of the substrate they are covering.

For opaque materials coated or covered with non-opaque coatings or coverings the LRV values are valid where the specimen is fully representative of the materials and the coating or covering.

Where surfaces have a surface texture of ≥2 mm and the material, coating or covering is uniform, the surface texture may be reduced to <2 mm and the LRV measured in accordance with this standard.

It is emphasised that, by using this standard, the LRV of any colour can be determined.

NOTE 3 Annex A shows the LRV of colours within BS 4800.