Industrial Color Challenges

By Martin Bide, President, AATCC

University of Rhode Island

The American Association of Textile Chemists and Colorists (AATCC) is one of the founding societies of the Inter-Society Color Council (ISCC), and the two organizations hold occasional joint symposia. The latest of these took place in Charlotte, N.C. on February 22-23, with around 100 attendees listening to talks centered on the theme of “Industrial Color Challenges.” The steering committee, consisting of Ann Laidlaw, Sy Commanday, Frank O’Donnell, and David Hinks assembled a program that was both wide-ranging and coherent.

Many attendees from retail store chains were present to hear their peers describe the challenges of communicating color through the supply chain. Keith Hoover of JC Penney revealed “The Truth About Color” and the cost of rejecting lab dips that are approvable when visual evaluation takes precedence over instrumental evaluation, as shown by little or no reduction in DEcmc between standard and submit over four iterations. Later, he compared the “Two World Views Of Global Color Communication,” the (chaotic) evolutionary model and intelligent design as they apply to color, lab dips, and production. Ann Laidlaw of X-Rite revealed all about Digital Color Communication and in doing so included timely reminders of the factors that must be controlled in a digital color supply chain. Once implemented, Laidlaw recommended that traffic in the approval process be analyzed, supplier performance be monitored, and color standards be monitored. She agreed with Hoover’s conclusions about the cost of rejecting lab dips that could and should be passed, and referred to a study indicating that color comments of close matches are often erroneous. Jean Hoskin of Macy’s described her challenges in getting a consistent color approach in an organization that owns many brands, while also selling several others. Visual color decisions can be made more quickly if judgments can be made via an on-screen, virtual light-box. Leslie McIntosh of Datacolor described such a device, and the need to include a “chromatic adaption” mechanism to make allowance for the display limitations of a CRT screen. She indicated that a major retailer has performed 250 virtual evaluations per day and found 97% agreement with subsequent examination of the real samples.

Those involved in the practical application of color to materials heard Richard Aspland of Clemson University discuss the coloration and finishing of nonwoven fabrics with challenges greater than those faced by dyers of woven and knitted fabrics. He concluded that continuous, open-width processing is most advantageous. Sy Commanday reported on many of the challenges he has faced as a consultant to those matching color in melt-spun fibers, particularly the occasional unpredictable behavior of certain pigment mixtures. The wide range of materials present in automobile interiors produces special challenges to both designers and the producers if they are to avoid metamerism or variable rates of fading. Jim Harper of TechmerPM proposed a solution based on synchronous development of materials from a limited set of primary pigments and evaluation via visualization software in a calibrated visual environment, thus reducing the time between design and a new model making its first appearance.

Some colors present particular challenges in their measurement. Larry Steenhoek and Allen Rodrigues of DuPont introduced a suggested standard method of Gonioapparent Color Measurement for metallic and interference pigment colors in automotive paints. They demonstrated that three angles of measurement are sufficient to characterize the metallics, while work on interference colors is continuing within ASTM. Roland Connolly of X-Rite described the difficulties of evaluating whites instrumentally and visually. He described the factors that must be controlled beyond those for non-white, non-fluorescent colors, and the problems that arise by using non-textile standards for such measurements. His work has led to a new AATCC standard evaluation procedure for UV energy calibration and an associated UVT standard that AATCC will supply. Accurate measurement also requires careful control of conditions, and Chris Hips of Datacolor described experiments to show how rapidly colors might change as they are brought out of conditioned areas to be measured.

The continuing search for better color difference equations and color spaces covers both the work to develop them, and their subsequent evaluation and acceptance by international bodies. Rolf Kuehni, AATCC’s 2005 Olney medallist, suggested that “Color Perception and Color Difference Estimation are Complex Processes,” emphasizing the loose relationship between perceived color and the light stimulus entering the eye. He described recent work that examined the variability of observers in making color difference judgments, and implied that the holy grail of a perfect color difference formula may remain elusive. David Hinks discussed the control of Color Difference and Color Constancy for multiple substrates. He went on to share some results of his work to compare CMC and CIEDE00 equations, and suggested some advantages of using naïve observers. Further work might reveal the maximum performance possible via instrumental color difference. Frank O’Donnell of Sherwin Williams showed an extensive series of 3D comparisons of Color Solids in the search for a Uniform Color Space, concluding that DIN 99d space appears to be the most (circularly) uniform for paint samples. Ronnier Luo of Leeds University described the development work involved in digital gray scale evaluations of colorfastness. He went on to describe some elegant work in color and emotion in different countries and using the data to derive a formula to predict color harmony, and a resulting harmonious color solid. His model would seem to offer a valuable tool for future designers.

Ellen Carter, editor of Color Research and Application, reviewed forthcoming articles in that journal that would be of particular relevance to conference attendees, focusing on measurement reproducibility, fluorescence and color appearance, and how researchers can use the benefits of electronic publishing. She went on to summarize the current issues being discussed by the CIE, particularly those that will be covered at the quadrennial meeting in Beijing later this year. That information dovetailed nicely with NCSU’s David Hinks review of Current Color Projects in ISO and ASTM. These included the work in ISO on absolute whiteness, color inconstancy, color difference and digital imaging, and ASTM’s work on gloss, and a new Color Rendering Index.

There is no light without color. In talking about “Best Practices For Measurement of Lighting” Nick Lena of Konica Minolta gave the audience a timely reminder of the ways in which light quality and quantity are measured, and the differences between photometric and radiometric units in doing so. Philip Bradfield of Tailored Lighting Inc. told of experiments and his experience in many situations, especially in museums, that a continuous spectrum light of around 3,500K revealed color better than did those of higher or lower color temperatures.

On the Thursday evening, attendees enjoyed a reception sponsored by BYK-Gardner, Datacolor, GTI Graphics Technology, Konica Minolta Sensing Americas, and X-Rite Inc. Many thanks to those companies.

The general conclusion at the end of the two days was that ISCC and AATCC should work together to produce the next joint seminar sooner than the 10 or more years since the last one. For those that missed this one, AATCC is selling copies of speaker presentations.