Standard Setup Rules for Four Point Greige Perches
Standard four-point greige perches require a 45-60 degree tilt, 1200+ lux D65 lighting, synchronized tension drive, and strict ASTM D5430 demerit point scoring.
Color Rendering Index
Source Fidelity
Standard measurement of light quality determines how accurately an artificial source reveals the true colors of dyed textiles compared to natural daylight. A high color rendering index is necessary in the linen inspection room to ensure that the subtle shades of flax fabric are evaluated correctly. The grader notes this light quality value in the daily room log.
While the mill’s own standard permits a value of ninety, the buyer’s acceptance criteria for premium linen requires a minimum of ninety-five to prevent shade discrepancies at retail. When evaluating fine linen yarns, an insufficient light source can lead to incorrect grading of yarn hairiness and slub distribution because shadows are rendered poorly.
Light Measurement
Evaluation of eight standardized pastel color samples provides the basis for this quantitative metric. The test light source is compared directly to a reference illuminant of the same color temperature. In the case of bleached linen, poor color rendering can mask yellowing or uneven bleaching, leading to false passes.
The resulting value is recorded on the lighting fixture’s certification document in the facility maintenance database.
Quality Standard
Maintaining consistent color across different production lots depends on the accuracy of the grading station lights. If the index drops below the specified minimum, the inspection is invalid and must be postponed until the lamps are replaced. This rule is enforced during the pre-shipment inspection of export-grade linen cloth.
Correct light rendering is checked and verified in the pre-shipment compliance report.