Dyed or Printed material is exposed in day light / artificial xenon arc lamp light to assess the Light fastness Property.It is assessed on a scale of eight (1……..8): 1 representing the least fastness and 8 the best.
A specimen of the textile is exposed to daylight under prescribed conditions, including protection from rain, along with eight dyed wool standards. The fastness is assessed by comparing the change in color of the specimen with that of the standards.
Blue wool standards produced in Europe are identified by the numerical designation 1 to 8. These standards are blue wool clothes dyed with the dyes listed below. The range from 1 (very low light fastness) to 8 (very high light fastness).
List Of Standard Wool Dyes
|S.No||LF dye rating||CI Designation||Chemical class|
|1||Acilan Brilliant Blue FFR||CI Acid Blue 104||Triaryl methane|
|2||Acilan Brilliant Blue FFB||CI Acid Blue 109||Triaryl methane|
|3||Coomassie Brilliant Blue R||CI Acid Blue 83||Triaryl methane|
|4||Supramine Blue EG||CI Acid Blue 121||Azine|
|5||Solway Blue EG||CI Acid Blue 47||Anthraquinonoid|
|6||Alizarin Light Blue 4GL||CI Acid Blue 23||Anthraquinonoid|
|7||Soledon Blue 4 BC pdr||CI Solubilised Vat Blue 5||Indigoid|
|8||Indigosol Blue AGG||CI Solubilised Vat Blue 8||Indigoid|
Table – List Of Standard Wool Dyes
The dyeing strength in both of the standard systems of 1 to 8 are omitted because of certain manufacturing problems but the sets of the standard dyeing are marketed after getting them matched in the depth of shade and fading rate with those of the master set.
Assessment Of Light Fastness
Compare the change in color of the test specimen with the changes which have occurred in the standard patterns. The light fastness of the specimen is the number of the standard pattern which shows similar changes in color ( the Visual contrast between the exposed and unexposed portions of the specimen). If the specimen shows changes in color, approximately half way between two standards, half rating may be given for eg, 3 – 4.
Blue Wool Scale Rating