Metallic inks shine on

As the quality of metallic inks improve, their roles in package printing are greatly expanding.

LIKE HOWARD CARTER, who unearthed the sparkling splendor of King Tutankhamen's tomb 81 years ago, package printers are discovering a valuable glimmering brilliance of their own: metallic inks.

The shiny, eye-catching inks have been used for years due to their ability to make packages stand out on store shelves and to create a certain air about packages. Gold inks pop off the shelf and give a look of tradition and richness. Silver inks give a similar appeal, and can also make the product appear cutting edge and high tech.

In general, said Norbert Hobrath, director of marketing and communications at Eckart America LP (Painesville, Ohio), "Metallic inks add a special prestige to the package."

A cost-effective substitute

Package printers are always looking to save time and money without sacrificing quality. Metallic inks can help. Now smoother and more brilliant than ever before, metallic inks are often substituted for applications like foil stamping and metallized substrates, because they look good and cost less.

"Metallic inks, enhanced by in-line embossing, can go some way to mimicking the graphic impact of foiling, but at a significantly lower cost and a resulting shorter turn time," said Duncan Watson, Shorewood Packaging's (New York) vice president of creative services and marketing. "Additional manufacturing passes, such as foil stamping, can be an issue at a time when we see the trend for ever decreasing turn times on jobs."

John Signet, marketing manager at Water Ink Technologies (Lincolnton, N.C.), added, "In many instances, the label or package buyer is finding that these bright metallic inks can meet their graphic requirements at a much lower cost than foil, as well as provide the converter with a broader range of production options."

By using foil-effect metallic inks made from a vacuum metallized process to replace hot foiling, a change in graphics requires only a plate change and not an expensive and time-consuming process to make a hot stamp die, said Tom Hammer, director of product portfolios at Akzo Nobel Inks (Plymouth, Minn.). "This opens up new markets to achieving foil effect where using foil was once cost prohibitive," he said.

Less waste is another benefit of metallic inks over other applications. While a lot of waste foil is left after a run, metallic inks are used in-line and on an as-needed basis, explained Ed Dedman, SICPA's (Brooklyn Park, Minn.) marketing development manager. "Using metallic inks allows for application only where you want the image, with no waste," Dedman said.

According to Pat Neary, corporate inks and coatings technology manager for Shorewood, there is even an environmental benefit to using some metallic inks. Shorewood's Shorebright metallics are environmentally friendly and very brilliant, but they do not produce the harmful effects as some foil boards, which are laminated with plastics and don't effectively biodegrade in land fills, he said.

Important ink

The biggest news in metallic inks are vacuum metallized pigments (VMPs). VMPs, and their ultra-high sheen and relative low cost, are credited with a recent increase in the diversity and demand of alternative metallic ink applications.

Ink suppliers rave about the smooth, brilliant, and clean qualities of VMPs that give the ink a mirror effect. They also boast that, when reverse printed on a clear label, VMPs look like foil.

"Standard metallic ink like 877 in the Pantone Book is a gray looking metallic, with a little sparkle and sheen to it," said Dedman. "Compare that to the super bright of VMPs, and the difference is like night and day. It's like the difference between standard metallic inks and foils."

VMPs are produced differently than standard metallic inks, explained Mike Buystedt, Akzo Nobel Inks' director of new market development. While standard inks are produced through a flaking process, Buystedt said, "VMPs actually consist of pigments taken off something that has been vacuum metallized on film, and those pigments are made into ink. They have a very high sheen because they lay flatter when they orientate themselves on the ink film. They orientate themselves very smoothly, which gives them a high reflective level. Standard metallic inks orientate themselves more rigidly so their reflectance is more scattered, and therefore less brilliant."

Overcoming difficulties

Despite the brilliance and diversity of metallic inks, there are still some barriers to be overcome.

Using metallic inks with offset printing processes has always been a challenge. Because the offset process prints from a planographic surface, said Neary, "The maximum printable particle size is substantially smaller than those that can typically be printed gravure."

However, new technologies and inks are making offset and metallic inks a very feasible combination. "This means brilliance can be achieved without the expense of gravure engravings, and this is obviously beneficial for medium- to short-run jobs that are more ideally suited for offset," Neary said.

Measuring metallic inks for color accuracy is another problem. With more brand owners using metallic inks, and new trends arising that focus on printing color inks over metallics and a growing demand for colored metallic inks, color measurement is important. But the difficulty is that metallic particles in the ink scatter light, making it very hard for an instrument to measure color with accuracy.

"Variations from batch to batch (primarily of paperboard and pigment size distribution and sometimes surface oxidation); job-to-job variables (dynamics of particle orientation application in the ink-film-splitting process); and even dynamic variables like temperature, press speed, and surface tension interactions within a job make it difficult to maintain light scattering variation that is acceptable to a spectrophotometer," explained Neary.

This difficulty can be overcome by using a spherical spectrophotometer, Neary said. Most printers use a dual-angle spectrophotometer, which measures reflected light at two specific angles. Since metallic ink scatters light at innumerable angles and the dual-angle spectrophotometer only measures light at two angles, the readings are often inconsistent.

"It is generally accepted that spherical spectrophotometers more effectively sample the reflected light and should, therefore, provide significantly better accuracy for metallics than dual-angle spectrophotometers," Neary said.

by: Kate Sharon