Textile Colour Measurement: Measuring the Colourant Strength of Dyes in Fabric and Garments
#color #spectrophotometer #dyes #vista #ageral2
Workshop 3 – Measuring the Colourant Strength of Dyes in Fabric and Garments.
It is time to discuss measuring the colourant strength of dyes—a topic that’s critical but often underutilized in the dyeing industry. Understanding how strong a dye is can make a huge difference in maintaining consistent colour quality, adjusting formulations with precision, and ensuring smooth collaboration with suppliers. Today, we’ll explore two key methods that help colour professionals quantify dye strength and improve colour performance: the static method and the dynamic method.
Static Method – Measuring Transmittance.
The Static Method is a proven technique for evaluating dye solutions in their original liquid form. This approach uses UV-Visible spectrophotometry to measure how much light passes through the sample — revealing the dye’s optical density and concentration without requiring a specific starting formulation.
How It Works:
Prepare the dye solution in deionized (DI) water and transfer it to a 10 mm optical glass cuvette.
Place the cuvette in a HunterLab transmission spectrophotometer—such as the Vista®.
Standardize the instrument for transmission mode using the appropriate reference standards.
Measure the absorbance of the sample and compare it against a known reference or standard.
Key control factors—like solution temperature, complete dye dissolution, and fixed measurement timing—are essential to ensure data accuracy and repeatability.
Why is this useful? Because even slight variations in dye concentration can change how the dye interacts with fabric. This method gives colourists a full spectral profile — far more informative than single-point absorbance measurements used in basic UV-Vis tools.
Dynamic Method – Measuring Reflectance.
Now let’s move to the dynamic method, which is more familiar in textile settings. This approach involves evaluating fabric samples that have been dyed using standard and incoming dye batches.
Steps include:
Prepare lab dips with equal dye concentrations, weight, and dyeing time.
Place samples on a white background to standardize reflectance.
Use directional colour spectrophotometers like Agera® L2.
Compare the reflectance of both samples under the same lighting conditions.
This method provides real-world insights into how a dye behaves on fabric, capturing critical variables like dye penetration and pick-up ratio.
L* values are especially telling: lower L* indicates darker shades, usually from higher dye concentrations. Levi Strauss, for example, uses the b/L ratio to assess indigo dye depth.
Science Behind Dye Strength – Kubelka-Munk Theory.
To understand why these methods matter, we need to look at the Kubelka-Munk equation. It relates a dye’s colourant strength to how it absorbs and scatters light. This gives rise to K/S values, which quantify dye performance.
Imagine comparing two blue dyes. At first glance, they may look the same. But their spectral curves might show different shapes, indicating different absorption behaviors. Sample 2 might show a colourant strength of 76.9990% versus a standard. That’s a meaningful difference — confirmed by higher K/S values like compared to 1.4492 compare to 1.8821. This tells us Sample 1 (standard) will produce a deeper shade and likely require less dye in production.
Scales and Indices Used.
To evaluate colour differences and dye strength, professionals use:
Colour scales: CIELab, CIELCh, Yxy
Indices: %Colourant Strength, Dominant Wavelength, Metamerism Index, Excitation Purity
Differences: ΔE*, Δh*, ΔC*, Δa*, Δb*, and ΔMetamerism Index.
Practical Tips for Better Standardization.
For consistent results:
Calibrate instruments regularly
Keep dye concentration, fabric weight, and time consistent
Apply proper dilution techniques for transmission measurements
Maintain consistent environmental conditions
Using both static and dynamic methods gives you a more complete picture of dye performance. The static method uncovers detailed spectral and chromaticity data, while the dynamic method shows how dyes behave on actual fabric under real conditions.
Together, they provide a powerful toolkit for ensuring colour consistency, improving process control, and reducing waste.
https://www.hunterlab.com/en/
Workshop 3 – Measuring the Colourant Strength of Dyes in Fabric and Garments.
It is time to discuss measuring the colourant strength of dyes—a topic that’s critical but often underutilized in the dyeing industry. Understanding how strong a dye is can make a huge difference in maintaining consistent colour quality, adjusting formulations with precision, and ensuring smooth collaboration with suppliers. Today, we’ll explore two key methods that help colour professionals quantify dye strength and improve colour performance: the static method and the dynamic method.
Static Method – Measuring Transmittance.
The Static Method is a proven technique for evaluating dye solutions in their original liquid form. This approach uses UV-Visible spectrophotometry to measure how much light passes through the sample — revealing the dye’s optical density and concentration without requiring a specific starting formulation.
How It Works:
Prepare the dye solution in deionized (DI) water and transfer it to a 10 mm optical glass cuvette.
Place the cuvette in a HunterLab transmission spectrophotometer—such as the Vista®.
Standardize the instrument for transmission mode using the appropriate reference standards.
Measure the absorbance of the sample and compare it against a known reference or standard.
Key control factors—like solution temperature, complete dye dissolution, and fixed measurement timing—are essential to ensure data accuracy and repeatability.
Why is this useful? Because even slight variations in dye concentration can change how the dye interacts with fabric. This method gives colourists a full spectral profile — far more informative than single-point absorbance measurements used in basic UV-Vis tools.
Dynamic Method – Measuring Reflectance.
Now let’s move to the dynamic method, which is more familiar in textile settings. This approach involves evaluating fabric samples that have been dyed using standard and incoming dye batches.
Steps include:
Prepare lab dips with equal dye concentrations, weight, and dyeing time.
Place samples on a white background to standardize reflectance.
Use directional colour spectrophotometers like Agera® L2.
Compare the reflectance of both samples under the same lighting conditions.
This method provides real-world insights into how a dye behaves on fabric, capturing critical variables like dye penetration and pick-up ratio.
L* values are especially telling: lower L* indicates darker shades, usually from higher dye concentrations. Levi Strauss, for example, uses the b/L ratio to assess indigo dye depth.
Science Behind Dye Strength – Kubelka-Munk Theory.
To understand why these methods matter, we need to look at the Kubelka-Munk equation. It relates a dye’s colourant strength to how it absorbs and scatters light. This gives rise to K/S values, which quantify dye performance.
Imagine comparing two blue dyes. At first glance, they may look the same. But their spectral curves might show different shapes, indicating different absorption behaviors. Sample 2 might show a colourant strength of 76.9990% versus a standard. That’s a meaningful difference — confirmed by higher K/S values like compared to 1.4492 compare to 1.8821. This tells us Sample 1 (standard) will produce a deeper shade and likely require less dye in production.
Scales and Indices Used.
To evaluate colour differences and dye strength, professionals use:
Colour scales: CIELab, CIELCh, Yxy
Indices: %Colourant Strength, Dominant Wavelength, Metamerism Index, Excitation Purity
Differences: ΔE*, Δh*, ΔC*, Δa*, Δb*, and ΔMetamerism Index.
Practical Tips for Better Standardization.
For consistent results:
Calibrate instruments regularly
Keep dye concentration, fabric weight, and time consistent
Apply proper dilution techniques for transmission measurements
Maintain consistent environmental conditions
Using both static and dynamic methods gives you a more complete picture of dye performance. The static method uncovers detailed spectral and chromaticity data, while the dynamic method shows how dyes behave on actual fabric under real conditions.
Together, they provide a powerful toolkit for ensuring colour consistency, improving process control, and reducing waste.
https://www.hunterlab.com/en/