SDCE Light Fastness Standards 1–8 (Each pattern size: 15 × 25 cm)

The SDC Blue Wool Fabric Set consists of eight wool fabrics dyed with carefully specified blue dyes to create a standardized light fastness scale. The range represents performance levels from very low to very high light fastness, forming a numerical scale from Grade 1 to Grade 8—where Grade 1 indicates the lowest resistance to light and Grade 8 indicates the highest.

These standards are used to assess and grade fabrics for light fastness by comparing colour change with the Grey Scale for Change in Colour. The results help predict product suitability for specific end uses. Typically, apparel fabrics require a minimum rating of Grade 4, while furnishing fabrics generally require Grade 6 or higher.

The Blue Wool Standards are widely used in the ISO 105 B series of light fastness tests and may also be used in combination with Humidity Control fabric for machine calibration purposes.

To complement the Blue Wool range, specially prepared mounting cards are available. These cards are free from optical brightening agents, ensuring accurate grading without background colour interference. Since background colour can influence visual assessment, the neutral mounting card enhances consistency and reliability in evaluation.