Imagine you have created a whole new line of jackets for your brand that are bluish gray in color, and you have installed zippers into these jackets that you thought were the same bluish gray color. However, when you take one of those jackets outside into daylight, the zipper inside of the jacket appears to be grayer in color than blue, and it really does not match the jacket at all. This phenomenon is known as metamerism where colored objects appear to match in one light source, but not in another.
In order to avoid metamerism, YKK recommends matching your fabric color with the YKK Color Card for zippers under a D65 light source. According to the article, “What is D65 and what is it used for?,” D65 is a light source that is used in industries that require a simulation of natural daylight, such as the apparel, digital art, film, photography and other visually demanding industries.
D65 is a widely used color standard for measuring white point. We discuss both the D65 spectrum as well as its chromaticity coordinates.
The article, “Light Sources & Metamerism,” found in the YKK Zipper Usage Instruction Manual, advises that a selection of a light source other than D65 for color matching with the standard YKK Color Card may result in a difference in color found between a dyed zipper and a garment when they are subjected to different lighting.
The article goes on to say that some common problems due to metamerism include a noticeable difference in color observed between a garment fabric and a zipper under fluorescent lighting in an office; a color difference found among zipper components, i.e. zipper tape, slider and elements (zipper chain); and problems with customer selected and approved zipper tape matching a garment fabric based on the YKK Color Card due to using a light source other than D65.
YKK Product Manual
To minimize a color difference due to metamerism, YKK advises using a D65 light source for all standard colors selected from the YKK Color Card. If a light source other than D65 is used (such as CWF, TL84, V3000, INCA), the company suggests specifying for DTM (Dye-to-match) under the specific light source for color approval.
In addition, YKK states that for DTM processing, customers are advised to submit fabrics that are more than 3cm x 3cm in size in order to ensure high accuracy in color matching and assessment.