Cotton colour grading
The colour of cotton fibre is one of the parameters that determine its value. We explain how cotton colour is assessed and how the world's standards differ.
Why cotton colour matters
The colour of raw cotton affects its suitability for dyeing and its price. It is assessed by two parameters: the reflectance degree Rd (brightness — how bright the fibre is) and the yellowness degree +b (how yellow). These two values place a sample on the cotton colour chart and assign it a colour grade.
Different standards worldwide
Historically, cotton colour was assessed visually against physical standards. Today instrumental measurement dominates, but the grading standards differ between countries:
- USDA (United States) — the most widely cited colour-grade system, based on the Rd and +b parameters, originally derived with the Nickerson-Hunter colorimeter and today with HVI (High Volume Instrument) systems.
- Other national and regional systems — China, India and other major producers use their own grades and standards, which do not always map 1:1 to the USDA scale.
These discrepancies complicate international trade, which is why there is a growing push toward objective instrumental measurement and a common colour description (Rd, +b and CIE L*a*b*) that is unambiguous regardless of country.
Measurement in practice
For objective colour assessment of fibre, yarn and fabric, spectrophotometers and colorimeters are used, reporting Rd, +b, whiteness index, yellowness index and CIE L*a*b* coordinates at once. Learn more about colour control in textiles on the textile applications page.
Frequently asked questions
How is cotton colour assessed?
By two parameters: the reflectance degree Rd (brightness) and the yellowness degree +b. Their combination sets the colour grade on the cotton colour chart. The measurement is made instrumentally — with a colorimeter or spectrophotometer.
Why do grading standards differ?
Individual countries developed their own grade systems and standards (e.g. USDA in the US, separate systems in China or India). They do not always map 1:1, which complicates trade — hence the push for an objective colour description with common parameters.
What is HVI in the context of cotton colour?
HVI (High Volume Instrument) is an automated system for measuring cotton parameters, including colour (Rd, +b). It replaced visual assessment and the original Nickerson-Hunter colorimeter, providing fast, repeatable measurement of large lots.