Color Fastness

Definition and Overview

Color fastness is a quality evaluation used to check the color durability of dyed or printed textile products. It examines how little the original color changes when exposed to influences during use or care, and how little it stains other fabrics it comes into contact with.

In evaluation, fading and color change, where the color itself becomes lighter or the tone changes, are distinguished from staining, where color transfers to attached fabrics such as white cloth. Results vary depending on the fabric color, dyes or pigments, type of fiber, processing conditions, and other factors.

• Wash fastness: resistance to fading and staining caused by washing.
• Rubbing fastness: resistance to color transfer when rubbed in dry or wet conditions.
• Sweat fastness: resistance to fading and staining caused by liquids simulating sweat.
• Light fastness: resistance to fading and discoloration caused by exposure to light.

Features and Product Impact

If color fastness is not sufficient for the intended applications, color transfer during washing, staining due to friction with bags or chairs, and fading in areas exposed to sunlight may occur. Dark colors, vivid colors, and products that are easily wetted may require especially careful checking.

Color fastness does not directly indicate fabric strength or shrink resistance. Even with the same color name or the same fiber composition, differences can occur depending on the dyeing method, aftertreatment, depth of shade, and lot, so it is important to check each color and each fabric individually.

Main Applications and How to Evaluate

For shirts, cut-and-sew items, underwear, and sportswear that are washed regularly, check wash and sweat fastness according to the intended applications. For dark casual wear such as denim, color transfer caused by rubbing should also be considered at the planning stage.

For curtains, products used near windows, and clothing worn outdoors, light resistance affects the appearance of the product. Include linings, accessories, and printed areas, and select evaluation items based on the light-colored materials they may contact and the wearing and storage environment.

• When combined with white or light-colored attached fabrics or linings, check the staining evaluation.
• If exposure to sweat or rain is possible, also pay attention to color transfer from rubbing when wet.
• For printed fabrics, check the required performance for both the pattern area and the ground color area.

Selection and Handling Notes

When selecting fabric, confirm the required test items, evaluation methods, target colors, and test-result lot with the supplier. Required levels vary depending on product applications, buyer standards, and care labels, so confirm the test conditions as well as the numbers.

For dark-colored items and color-blocked products, handling in accordance with the care label is necessary, such as washing separately or with similar colors for the initial wash. Since leaving items wet or rubbing them strongly can cause color transfer, labeling for wearers should also be considered.

At the prototyping stage, also check changes in appearance caused by sewing, washing processes, pleating, and other post-manufacturing treatments. Even if there are test results for the fabric alone, it is important to separately check the risk of staining due to combinations with trims and processing.

Differences from Similar Terms

Shrinkage ratio refers to the degree of dimensional change in fabric due to washing and similar processes, and its evaluation target is different from color fastness, which indicates color durability. Pilling is the phenomenon in which fuzz balls form due to friction, and skew is the phenomenon in which the grain of knitted or woven fabric twists after washing.

Yarn dyed, piece dyed, and printed describe the process or method of adding color. These methods can affect color fastness, but the process name itself does not guarantee a certain level of color fastness.

Frequently Asked Questions

If a fabric has high color fastness, will fading or color transfer never occur?

Even with good color fastness, fading or color transfer may still occur. Under conditions such as strongly rubbing a dark-colored product while wet, soaking it in water for a long time, or using detergent or bleach improperly, effects may appear. Handle according to the care label.

Should wash fastness or rubbing fastness be checked?

In principle, both should be checked according to the intended applications. For clothing that is washed frequently, wash fastness is important. For dark-colored garments that may contact bags, be subject to sitting, or get wet from sweat or rain, rubbing fastness should also be checked. The required test items are determined by the product's usage environment.

Is yarn dyed fabric more colorfast than piece dyed fabric?

Color fastness cannot be judged as better or worse simply from whether the fabric is yarn dyed or piece dyed. Fiber type, dyes or pigments, depth of shade, dyeing and washing conditions, and aftertreatment all affect the result. Do not judge by the fabric production method name; it is necessary to check test results for the color and lot to be adopted.