Development of Reference Cotton Materials for Calibration and Validation of Fiber Fineness and Maturity Measurements

Fiber maturity and fineness are important cotton quality attributes, yet the cross-section method used as the reference measurement technique is labor-intensive and impractical for routine testing. To address the diminishing supply of the reference cotton set developed by Hequet et al. a new set of commercially produced whole-bale reference materials was established for calibration and validation of maturity and fineness measurements. Eight reference bales were selected, blended using standardized procedures, and characterized using High Volume Instrument (HVI), Advanced Fiber Information System (AFIS), and cross-section measurements. More than 30,000 fiber cross-sections were analyzed per bale, providing robust estimates of maturity (θ) and standard fineness (Hs). The reference set spans a maturity range of 0.46–0.58 and a standard fineness range of 129–224 mtex. Although individual fiber measurements overlapped substantially, sample-level aggregation produced stable estimates, with coefficients of variation among sample means of 2.3–3.6%. Comparisons between cross-section and AFIS measurements showed strong bale-level relationships while highlighting systematic differences between measurement principles. The resulting reference materials provide substantially larger quantities of cotton than the original reference set and are intended to support development, calibration, and validation of current and emerging technologies for measuring fiber maturity and fineness.