| Matching inspiration - the effect of substrate on color by Maria C.Thiry, AATCC Review, Apr 2004 The flash of inspiration for a color can come from anywhere. And designers often ask puzzled – and sometimes frustrated – manufacturers to produce that same color on a textile. “In today's world what we are matching to can be anything, a leaf, a photograph – anything that is an inspiration,” notes Michael Bradbury of Color Solutions International. Sometimes the colors are unachievable in textiles. That's why it's important to use the final substrate for a color standard as early as possible in the process. There are times designers ask manufacturers to produce colors that match across different substrates. In some areas, such as intimate apparel, the various substrates involved are mostly textile substrates. But in some cases, such as automobile interiors and athletic shoes, designers ask manufacturers to match their color inspiration across widely different substrates. Even with just textile substrates, matching and controlling color between two or more substrates can be complicated due to different fibers, different levels of brightness, different surface effects, and different constructions. Today, technology is available to enable a closer match in color between two different substrates, but Datacolor's Karen Gaskins notes that, "Color is a very fuzzy science. Although the mathematics of color is very precise, and spectrophotometers measure color very accurately, our brains don't measure things the way spectrophotometers do. Many things affect the way we see color. The influence of substrate is one of those fuzzy areas." It is not always easy to match that flash of inspiration. Substrate
Texture
Brightness
Software and Intrumentation
Inconstancy and metatmerism
Trim and accesories
Ending up with the right colour -------------------------------------------------------------------------------------------------------- SUBSTRATE Matching Color One of the most common obstacles in matching color between different textile substrates is the simple fact that different textile fibers require different dyes. According to Brooks Tippett of Pantone, "Fiber type can play a large role in the matching process. Natural fibers react very differently to dyes than synthetic fibers do and the process is much harder to control. In addition, each fiber type has a corresponding dye class and these classes of dyes provide different color gamuts.” Some of the difficulty in matching color across substrates is due to the color standards chosen. Sometimes the single-substrate standards used by retailers are problematic. These standards can be set without consideration of fiber or construction. Fundamental things such as opacity make a single standard almost impossible to use in multicomponent products. Opacity affects shade— and leather and plastics are opaque but textiles are not. Lee Pek Seng of eWarna suggests that one way to coordinate standards for a multicomponent product is to "set a master referenced standard for comparing all the colors of the different substrates. This can be done by using software with a multi-compare or sort feature and acceptance will be based on those that can fit into the group." The process of matching colors across a variety of substrates is called harmoni-zation. "Harmonization often depends on visual assessment, to see if the different ways that the colors are represented on different fibers work together," says Bradbury. "Often, to be able to produce a multicomponent product like a running shoe or automotive interior in bulk, manufacturers need to have a standard for each component." Controlling Color Ann Laidlaw of GretagMacbeth notes that for multicomponent products, strict color matching requirements are necessary. "In cases where the standard is on a substrate different from the production substrate, plants often have informal 'internal' standards on production materials," says Laidlaw. "This works well if the retailer is working with only one manufacturer, but there can be problems when multiple sourcing is involved." "If five different locations supply different components, it's not a simple task to come up with a harmonious match," agrees Doug Bynum of Archroma. "There are limitations in areas of the color spectrum that can't be made in every class of dyes." 
--------------------------------------------------------------------------------------------------------- TEXTURE A fabric's construction (knit or woven) and surface characteristics (pile or satin) also influence the ability to accurately match color. According to Tippett, "Fabric construction plays a significant role in the depth and appearance of a color. Generally, woven fabrics provide more of a flat color appearance, while knits and jacquard fabrics add a shadowed, two-tone effect to the color. Also, higher thread count twill fabrics allow for deeper shades than low weight poplins." The influence of construction and surface characteristics highlights the difference between instrumental and visual color assessment. Instrumentally, sphere geometry is used to diffusely illuminate the sample. The sample is illuminated from many different angles and then evaluated from only one angle to eliminate the influence of texture. However, Gaskins says that when people visually evaluate the sample, the influence of texture does make a difference. A machine performs a color assessment but people perform an appearance assessment. There is a difference between the color (expressed as data) and the appearance (judged in a visual assessment). "We visually can't eliminate the influence of texture," notes Gaskins. It is often more difficult to mstm-mentally assess fabrics with heavy pile, so those fabrics are often assessed visually. Instrumental assessment is possible, according to Bradbury, but "accurate viewing conditions are very important. The carpet industry has developed some techniques to do it more accurately, but in the apparel industry, the difficulties are usually handled by giving a wider tolerance." --------------------------------------------------------------------------------------------------------- BRIGHTNESS Color and brightness of the substrate itself will often affect the final color on that substrate. Most synthetic fibers such as polyester come from a clear polymer. The color of the substrate can be controlled, as can the brightness. Natural fibers, like cotton, always have their own color, despite bleaching. "The whiteness index of a natural fabric can play a significant role in matching shades. Residual yellowness in a natural fabric can cause shades to have slight flare or prevent a completely clean look," says Tippett. Also, "Preparation may affect dye absorption (shade depth) and residual sizes and fabric finishes can create a challenging color match." Colors dyed on natural fibers like cotton will always appear flatter than colors dyed on synthetics. This may not be a problem unless you need to match colors on both natural and synthetic fabrics. "If you start with a bright fiber for bright shades and try to match to a delustered fiber or cotton, you can't really get a match. At best, you will get an interpretation of that target," says Bradbury. "Also, cotton fibers have a low level of sheen (gloss) when compared to nylon, silk, or polyester," says Tippett. "It can be very difficult to match a high-sheen color with a natural fabric and vice versa. If the standard is a bright substrate (nylon, for example), the color will be very hard to match on cotton. The cotton shade will always appear duller and possibly dirty. The exact opposite occurs if the standard is cotton and is being matched on a bright synthetic fabric. The color will always look too bright and is difficult to tone down." This is more of a problem with bright or light shades. According to Gretchen Adams of Victoria's Secret, designers understand that cotton fabrics can't achieve the same brightness as polyester fabrics. "We know we can't get both fabrics the same color, so we try to get them tonally similar." --------------------------------------------------------------------------------------------------------- SOFTWARE AND INSTRUMENTATION Software can help dyers compensate for differences in the brightness, transparency, and shine of different substrates in their color formulations. "Digital color information and formulation software play a big role in today's color matching," notes Tippett. "Formulation packages can overlap color gamuts across substrates using the dyehouse's primary colorants." Although software can help with dye formulation and instrumentation such as spectrophotometers can match spectral reflectance curves (color "fingerprints"), there are still many factors, such as texture, that affect the appearance of a color and will influence the color match. So mills must often refine the color through visual assessment. However, just because the technology can't locate a specific address yet, doesn't mean it doesn't get in the neighborhood. "We have found that some people quote the limitations as a way of doing nothing," says Gaskins. "But the instrumentation technology can get you closer to a starting formula that works. It saves time and you end up with a more consistent and balanced formula." --------------------------------------------------------------------------------------------------------- INCONSTANCY AND METAMERISM As well as using software, instrumentation, and procedures to accurately communicate color, manufacturers often use dye formulation software to control metamerism and color inconstancy. "Both of these factors are best handled at the formulation stage," comments Tippett. "Most formulation software packages allow users to choose colorant combinations based on cost, metamerism, and reproducibility. The newer programs also allow users to evaluate color inconstancy." Inconstancy Color inconstancy, or "flare," (the change in color of a single piece of fabric under different light sources) can be more difficult to control than metamerism. "Color inconstancy is one of the most poorly understood properties," says Bill Sherrill ofArchroma. "It's physics, not chemistry. Changing a formulation will do very little to change color inconstancy." According to RolfKuehni of North Carolina State University (NCSU), "Color constancy is conditional to light sources. It is not possible to make approximately constant colorations for more than two or at most three light sources. In other words, there are no colorations of constant appearance in any light source." Niraj Agarwal of Archroma says that, "Inconstancy is primarily determined by the color itself and only secondarily by the colorants used. Some colors with certain characteristic curve shapes will always be color inconstant regardless of the recipe used." Metamerism Metamerism is the situation in which fabrics have matching color under some light sources but not others. "Metamerism can only be controlled by using similar colorants in the color standard and the sample. Attempting to reduce the color inconstancy of a color standard does not in any way reduce the possibility of metamerism," says Agarwal. "It is entirely possible to get highly metameric matches for color constant shades and it is also possible to get nonmetameric matches for color inconstant shades." --------------------------------------------------------------------------------------------------------- TRIM AND ACCESSORIES The issues of matching color on different substrates become sharply focused when it comes to matching trim and accessories to a garment. "We make many garments that have to match each other," says Adams. "We use the same standard for up to as many as nine substrates on the same garment. We know that they will all go on the garment together. When matching the colors on these different substrates, we need to know yhere each substrate is located on the garment. It is important to know where the will go first—that will be our primary®^ substrate. We want the components to match in the same direction, hue, and strength. Edge laces and some trims are secondary and we let suppliers generally match those. The primary material is the primary match in a garment—everyone else needs to match to that and the standard or to shift the hue and depth to where we need them to be. Suppliers will sometimes make up a mockup of a garment if they are unsure. The garments that have four to five different fabrics from different countries arc challenging. Sometimes we need to share with the suppliers a sample of the primary matched fabric to give them hue and depth directions as a guide to achieve the standard and a matching garment." Even though Adams communicates standards digitally, she relies heavily on visual assessment for matching color between so many different substrates. "In the industry, most trim and accessories are often matched by eye. Because of the size of the samples, digital techniques can't easily be used. Also, items such as buttons are three dimensional so they are almost impossible to measure using current techniques," says Sue Williams of Global Color Solutions/DigiEye. "Emerging camera systems offer new possibilities for digitally communicating color for trim and accessories." "Digital color matching can be applied to trim products as long as the presentation method to the spectrophotometer can be controlled consistently," asserts Lee. "In the case of sewing threads, when preparing the sample cards, the winding lay and tension is very important. Poor winding lay will create areas of shadow and higher tension will render the thread to be perceived as a darker color. Zippers can be measured the same as fabric but the spectrophotometer will most likely be on small area view due to the small presentation area." --------------------------------------------------------------------------------------------------------- ENDING UP WITH THE RIGHT COLOR Despite technical advances and new technology and color services, capturing a designer's color inspiration on a textile isn't simple. This is especially true when the job involves matching the color of a standard substrate that is nothing like the color of the production substrate. Questions of substrate aside, conveying that color is a painstaking undertaking. "We know much more than we used to about how to accurately measure and communicate color," says Bradbury. "What is universal is a poor execution of what we know. People often don't put proper procedure into practice. They take shortcuts. And then what results is that we don't get the colors in the stores that the designers created." With all the technological tools at our disposal, "it is evident that despite technical advances, the job of the colorist will continue to remain in part an art," says Kuehni. Color, from inspiration, to communication, to fabrication, to appreciation—despite the complexities of physics and chemistry that enables it—is a human form of expression, after all. --------------------------------------------------------------------------------------------------------- |
