SDCE Blue Wool is a series of 8 wool fabrics dyed with specific blue dyes. This allows blue wool fabrics to be used from very low light fastness to very high light fastness. It has a numerical scale from 1 to 8 with 1 being the lowest light intensity and 8 being the best light intensity. These are used in the ISO 105 B series of tests and can be used in conjunction with the Humidity Control fabric for machine calibration.