Light fastness standard fabric, blue wool fabric (8 pieces / bag, grade 1 ~ 8), in accordance with ISO / BS standard. The wool fabrics dyed with special blue dyes of No.1 ~ No.8 series products provide blue wool in the range from very low light fastness to very high light fastness. They form an ordinal series from 1 to 8. 1 represents the lowest light fastness to 8 represents the highest light fastness. This product can grade the fabric with a gray scale meter for measuring color change, which is related to the performance during use, They are used in the tests of ISO 105 B series.