Paperboard

Make Me a Match

Posted: March 17, 2011 by

In the small town of Burneside in the U.K., age-old tradition and new technology have formed a harmonious relationship. The town grew up around the still privately held James Cropper Speciality paper mill, which was founded in 1845. Today, clients from over 50 countries rely on the wide range of tailor-made papers produced at the mill.
For luxury products, the most important element of this process is the ability to match and create a unique color on specialty paper. Though the Specialty Papers division’s library has 3,500 “live” shades, clients still request an average of eight to 10 new shades every week, so the company is prepared with computerized matches of another 12,700 colors.
New chairman Mark Cropper represents the sixth generation of his family to be involved with the paper mill. Cropper sat down with Package Design magazine to explain what luxury brand owners should know about color and specialty paper production.

PD: Explain the difference between pigments and dyes.
Mark Cropper: Pigments hold their depth of color more than chemical dyes, which can break down in certain light environments.
Some shades can only be achieved with pigments, which are very difficult to break down with light. Every dye has its own characteristics—almost like DNA. When our craftsmen are not sure of the exact components of a dye sample they receive, they begin a “forensic” investigation process.

PD: What other light factors affect the use of dyes?
Cropper: The instability of dye-induced color under different light sources is known as metamerism. A good example of metamerism is when a fabric looks a certain color when it’s displayed in a store, but then appears to change color when it’s inspected under another light source—usually when a purchaser has taken a product home.

PD: Is a strictly computerized color-match the most accurate?
Cropper: No. Even with a huge database of dyes and specialized software, a computerized match will not be perfect. To get a closer match, color technicians compare the color under light conditions at a setting of D65 as a primary source. D65 is a common standard illuminant measure, roughly equivalent to the mid-day sun in Western Europe. They also assess the color under fluorescent light typically used in retail stores and under common household lighting conditions. Technicians choose as the closest match the color that varies the least under all three light sources.

PD: Are there other considerations in finding a perfect match?
Cropper: Precision color-matching is just one element of a perfect match. In most applications, other paper attributes must be taken into consideration. For some paper grades—those with a short life span or with limited exposure to light—light-fastness is not an issue. However, for many applications, such as packaging, photo frames, or picture mount boards, it’s important that the paper color does not fade over time. In order to achieve high light-fast ratings, the colorants must be carefully chosen.

PD: How do you measure the light-fastness of a color?
Cropper: Light-fastness is the measure of a color’s ability to maintain its true shade under prolonged exposure to direct sunlight. The standard test for light-fastness is the Blue Wool Scale, which is a textile test to examine how fast garments will fade that has been adapted for use with paper. On the Blue Wool Scale, “1” indicates very low light-fastness and “8” indicates very high light-fastness. The scale equates to how long a colored paper can remain in direct sunlight before it fades, indicating the permanence of a dye or pigment. Pigments with greater permanence are more expensive than those that are less resilient to light.

PD: What are the options for customers seeking high resilience to light?
Cropper: Standard paper dyes have light-fastness ratings in the range of 2 to 4 on the Blue Wool scale, and special-order dyes can achieve a level of up to 6 on the scale. Using pigments is usually far more expensive, but specialty papers with pigments can achieve light-fastnesses up to 7 and 8.

PD: Do you ever tweak colors as the paper is being manufactured?
Cropper: Sure, adjustments can be made during the papermaking process. We’re constantly being pushed to develop new processes and methods by customers and clients. Though specialty paper has been our core focus for generations—and computer matching is a great tool—there is still an element of artistry and craftsmanship in the process.

PD: Give us an example of where artistry makes a difference.
Cropper: Well, customers always want a whiter white or a blacker black, so scientists in the company’s laboratories are always experimenting to create more shades. But even the most virginal white can also benefit from additives to produce a higher purity. Optical brightening agents and smidgeons of blue can be used to create a whiter-than-white effect. A slight tinge of blue tricks the eye into thinking a shade is whiter than it actually is.

PD: What do you see as the short- and long-term future of specialty papers in luxury packaging?
Cropper: Paper packaging is an essential element of the luxury industry and I am confident it will continue. The luxury market has high standards in terms of design, quality, and material integrity, requiring materials that are beautiful, functional, and environmentally strong. There are various independent associations working tirelessly to bring the needs of luxury brand owners and the final consumer together, and develop greener packaging. For these reasons, specialty papers, as natural and sustainable materials, will continue to grow as the material of choice.
 

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