Textile Colour Measurement: Measuring the Colour of Pre-Dyed and Dyed Cotton Yarns
#color #spectrophotometer #ageral2
Workshop 2 - Measuring the Colour of Pre-Dyed and Dyed Cotton Yarns.
Now we move on to the colour measurement of pre-dyed and dyed cotton yarns. Consistent, accurate colour assessment is essential to ensuring that textile products meet quality expectations. Whether you're evaluating yarns before dyeing or checking post-dye results, precise colour data helps reduce variability, support uniformity, and maintain control throughout the production process.
Why Measure Pre-Dyed Yarns.
Before dyeing takes place, it’s important to assess the natural colour of the yarn. This helps colourists adjust for batch variations and evaluate the yarn’s cleanliness and whiteness. When you reduce variation at this early stage, you set the foundation for better dye uptake and consistent final colour.
Demonstration.
We start by securing the yarn with a skein holder. This tool helps maintain uniform tension and opacity during measurement. When yarn layers are inconsistent in thickness or density, measurements can vary. The skein holder helps eliminate that problem and ensures accuracy.
The Challenges of Measuring Yarn on Cards or Looms.
Some mills choose to measure yarn by wrapping it onto cards or looms. While this can be convenient, it often introduces inconsistencies. Background colour can influence readings, and differences in fibre tension, humidity, or dye bath parameters can create additional variations.
Using standardized tools like skein holders or bobbin adapters gives more reliable, repeatable results across batches and environments.
Measuring Dyed Yarns for Quality.
For dyed yarns, colour consistency is everything. Small changes in dyeing variables can lead to visible differences between batches. To monitor this, operators use colour scales and indices to track:
Overall colour accuracy using ΔE*
Visual differences using Gray Scale ratings
Key metrics like Whiteness Index and Metamerism Index.
Demonstration.
We measure using the industry’s #1 colour spectrophotometers for dyed yarn, HunterLab’s Agera L2. This instrument can operate independently or be connected to EasyMatch QC software for deeper analysis. Agera L2 helps you evaluate colour precisely and maintain high standards in post-dye quality control.
Applying the Kubelka-Munk Algorithm.
Behind every accurate dyeing process is a bit of science. The Kubelka-Munk theory relates a yarn’s colour to its absorption and scattering properties, depending on dye concentration. Understanding this relationship allows mills to fine-tune their dye formulations and control shade outcomes more effectively.
Practical Tips for Reliable Colour Measurements.
To reduce variation in colour measurement:
Mount yarn samples with even tension and avoid twists
Ensure each layer is consistent and homogeneous
Use opacity correction when needed
Average multiple readings to eliminate outliers.
Common indices include:
CIELab, CIELCh, and Rdab colour scales
Whiteness Index (WI E313) for pre-dyed yarns
Metamerism Index (MI) for dyed yarns
ΔE* and Gray Scale for evaluating colour differences
These practices help operators standardize their process and maintain visual consistency.
Process Variables That Affect Yarn Colour.
Yarn colour is influenced by several variables. For example, L* values—representing lightness—change with dye concentration. Higher concentrations lower L* values, creating darker colours. Lower concentrations increase L* values, resulting in lighter shades. This applies across all dye types and colours.
Levi Strauss & Co. uses the b/L ratio as a benchmark for indigo depth. Other process factors include:
Fabric loading weight
Liquor ratio
Running rate
Cycle time
Dosing rate
Temperature
Adsorption rate.
Cotton yarn typically shows an 80% dye pick-up rate. Monitoring these parameters helps mills keep results consistent and reduce costly colour mismatches.
Recap and Takeaway.
Colour measurement is more than a technical process—it is a powerful tool for ensuring quality and consistency in textile production. By mastering these techniques, your mill can reduce variability, improve efficiency, and meet customer expectations every time.
https://www.hunterlab.com/en/
Workshop 2 - Measuring the Colour of Pre-Dyed and Dyed Cotton Yarns.
Now we move on to the colour measurement of pre-dyed and dyed cotton yarns. Consistent, accurate colour assessment is essential to ensuring that textile products meet quality expectations. Whether you're evaluating yarns before dyeing or checking post-dye results, precise colour data helps reduce variability, support uniformity, and maintain control throughout the production process.
Why Measure Pre-Dyed Yarns.
Before dyeing takes place, it’s important to assess the natural colour of the yarn. This helps colourists adjust for batch variations and evaluate the yarn’s cleanliness and whiteness. When you reduce variation at this early stage, you set the foundation for better dye uptake and consistent final colour.
Demonstration.
We start by securing the yarn with a skein holder. This tool helps maintain uniform tension and opacity during measurement. When yarn layers are inconsistent in thickness or density, measurements can vary. The skein holder helps eliminate that problem and ensures accuracy.
The Challenges of Measuring Yarn on Cards or Looms.
Some mills choose to measure yarn by wrapping it onto cards or looms. While this can be convenient, it often introduces inconsistencies. Background colour can influence readings, and differences in fibre tension, humidity, or dye bath parameters can create additional variations.
Using standardized tools like skein holders or bobbin adapters gives more reliable, repeatable results across batches and environments.
Measuring Dyed Yarns for Quality.
For dyed yarns, colour consistency is everything. Small changes in dyeing variables can lead to visible differences between batches. To monitor this, operators use colour scales and indices to track:
Overall colour accuracy using ΔE*
Visual differences using Gray Scale ratings
Key metrics like Whiteness Index and Metamerism Index.
Demonstration.
We measure using the industry’s #1 colour spectrophotometers for dyed yarn, HunterLab’s Agera L2. This instrument can operate independently or be connected to EasyMatch QC software for deeper analysis. Agera L2 helps you evaluate colour precisely and maintain high standards in post-dye quality control.
Applying the Kubelka-Munk Algorithm.
Behind every accurate dyeing process is a bit of science. The Kubelka-Munk theory relates a yarn’s colour to its absorption and scattering properties, depending on dye concentration. Understanding this relationship allows mills to fine-tune their dye formulations and control shade outcomes more effectively.
Practical Tips for Reliable Colour Measurements.
To reduce variation in colour measurement:
Mount yarn samples with even tension and avoid twists
Ensure each layer is consistent and homogeneous
Use opacity correction when needed
Average multiple readings to eliminate outliers.
Common indices include:
CIELab, CIELCh, and Rdab colour scales
Whiteness Index (WI E313) for pre-dyed yarns
Metamerism Index (MI) for dyed yarns
ΔE* and Gray Scale for evaluating colour differences
These practices help operators standardize their process and maintain visual consistency.
Process Variables That Affect Yarn Colour.
Yarn colour is influenced by several variables. For example, L* values—representing lightness—change with dye concentration. Higher concentrations lower L* values, creating darker colours. Lower concentrations increase L* values, resulting in lighter shades. This applies across all dye types and colours.
Levi Strauss & Co. uses the b/L ratio as a benchmark for indigo depth. Other process factors include:
Fabric loading weight
Liquor ratio
Running rate
Cycle time
Dosing rate
Temperature
Adsorption rate.
Cotton yarn typically shows an 80% dye pick-up rate. Monitoring these parameters helps mills keep results consistent and reduce costly colour mismatches.
Recap and Takeaway.
Colour measurement is more than a technical process—it is a powerful tool for ensuring quality and consistency in textile production. By mastering these techniques, your mill can reduce variability, improve efficiency, and meet customer expectations every time.
https://www.hunterlab.com/en/