ΔE
ΔE is a color-difference index that compares a reference color and a sample color using numerical values in color space to show how different they appear.
Contents6 sections
Definition and Overview
ΔE is a color-difference index that expresses the gap between a standard color and a sample color using numerical coordinates that quantify color. The smaller the value, the closer the two colors are; the larger the value, the greater the color difference. It is used for color matching in dyeing, fabric, trims, printing, and other applications.
Color-difference values are managed based on values obtained with a colorimeter, but there are multiple calculation methods for color difference. Even with the same sample, the evaluation may change if the formula, light source, or viewing conditions differ, so it is important not to compare values on their own.
Characteristics and Effect on Appearance
ΔE is not a value that indicates the properties of the color itself or the texture of the fabric; it is a management value that shows the difference between two colors. For that reason, even with the same ΔE, the impression people receive differs depending on whether the difference is in brightness, redness, yellowness, or another direction.
On materials with luster, nap, unevenness, or sheerness, the way the color looks changes depending on the viewing angle and background. Metamerism, in which the color-match appearance changes under different lighting, also occurs, so measured values are used together with visual inspection.
- Dark colors and low-brightness colors may stand out even with slight color differences.
- Fabric, sewing thread, tape, zipper, and other items of the same color are checked side by side.
- For yarn-dyed patterns, the ground color and pattern color may be checked separately for color difference.
Main Applications
In apparel, it is used for comparing lab dips and approval samples, managing lot-to-lot variation in mass production, checking color matching between fabric and trims, and confirming the color tone of prints. It is especially important for set-up-and-down items, panel designs, and specifications that show the lining, where color mismatch is likely to appear in the overall look.
It is not an index limited to a particular season or item, but for products that require a uniform color tone and consistency, such as light-colored shirts and blouses, formalwear, and uniforms, a color-difference standard may be defined in the specifications.
Selection and Handling Precautions
When placing an order, clearly define the reference physical sample, color number, measurement conditions, and the color-difference calculation method to be used, and share the acceptable range with the trading partner. Since the storage condition and changes over time of the reference sample also affect the judgment, manage it to avoid dirt, fading, and yellowing.
Color change due to washing, friction, sweat, sunlight, or heat treatment cannot be judged by the initial ΔE alone. Depending on the intended use of the product, various fastness tests must be checked, and color difference should be evaluated before and after washing or before and after processing.
During sewing, check the colors of the shell fabric, sewing thread, interlining, tape, and other materials under lighting equivalent to natural light. When combining different materials, differences in luster and surface reflection by material may make the colors appear not to match even if the color numbers are the same.
Differences from Similar Terms
Fastness is a performance measure that evaluates resistance to color change and transfer caused by washing, rubbing, light, and similar factors. In contrast, ΔE is a numerical expression of the difference between two colors compared at a given point in time, and does not indicate durability itself.
A lab dip is a small dyeing sample made before mass production. ΔE is a measurement index used to determine how close that lab dip or mass-produced fabric is to the approved color. Metamerism refers to the phenomenon in which the color-match relationship changes depending on the lighting.
Frequently Asked Questions
If the ΔE value is small, will the colors always look the same?
Not necessarily. It is affected by the direction of the color difference, the gloss and surface shape of the material, the lighting, the viewing angle, and surrounding colors. In addition to confirming ΔE through color measurement, it is important to place the actual materials together and make a visual judgment under the specified light source.
What points should be noted when checking color matching between fabric and trims?
Even with the same color number, fabric, sewing thread, zipper tape, resin trims, and similar items may use different materials or dyes, and color differences may become noticeable depending on the lighting. In addition to comparing them with the reference color, check them in multiple lighting conditions as adjacent combinations on the product.
Can color change after washing be evaluated only with ΔE?
The color change before and after washing can be quantified with ΔE, but transfer, staining of white areas, and surface changes must be checked separately. Make a judgment by combining tests for washing fastness and rubbing fastness suitable for the application with post-wash appearance and visual evaluation.
