BS 8475:2006 pdf free.Instrumental colour measurement of textiles – Method.
BS 8475 This British Standard specifies procedures to be used in preparingrepresentative textile materials for presentation to an instrumentappropriate for the measurement of surface colour. It includes procedures for acquiring the data for the determination of a numericalcolour specification.
The following referenced documents are indispensable for the application of this document. For dated references, only the referencecited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
The specimen is prepared and presented to the aperture of the selectedinstrument and its colour is measured.
Spectrophotometer, using one of the optical geometries specifiedin CIE Publication 15, for the measurement of reflectance throughoutthe visible spectrum.The preferred optical geometry of specimenillumination and viewing is diffuse/normal (d/0) as defined in CIE 15.NOTE The angle between the normal to the specimen and the a.cis of theviewing beam should not exceed 10°.
Tristimulus colorimeter, which may be used only for colourcomparisons of non-metameric materials.
The specimen shall be of a size adequate to completely cover theaperture of the instrument. Measurement shall be with the largestaperture possible.An area of the specimen that is uniform in colour,evenly constructed and clean shall be presented to the aperture of theinstrument, avoiding specimen irregularities or spots visible to the eyein the measurement.
The specimen shall be of sufficient thickness so as to be opaque.Allspecimens shall be measured in the same thickness where the colourdifference between specimens is being measured.
NOTE 1 Establishing opacity will depend upon the nature of thespecimen, e.g. fabric should be folded and yarn should be wound in multiple layers. If a specimen is not opaque, light passing through it willreflect from the backing material or holder causing an erroneous measurement. The opacity of a specimen may be checked by measuring itover a black background,and separately over a white background. If thecolour difference between these two measurements is within CMC(2:1)AE= 0.2, the prepared specimen is adequately opaque.
NOTE2 Care should be taken not to increase the thickness of the specimenbeyond that which is necessary to achieve practical opacity in order toavoid intrusion of the specimen beyond the plane of the measurement portof the instrument, which can itself cause error in measurement.
Present the specimen to the instrument in a flat and relaxed state.NOTE 3 Excessive tension on the mounted specimen can cause distortion,leading to erroneous measurements. If the mounting is too slack, shadowscan appear from the attendant wrinkling, giving incorrect measurements.BS 8475 pdf download.