Cold Foil Hot App

Cold foil technology, where foils are applied inline on high-speed sheetfed presses, is gaining traction in commercial print markets. Heightened customer demand for producing special effects—and cost and efficiency gains from applying foils inline—are moving the once highly specialized, offline process into the mainstream. These systems, mounted on sheetfed offset press units, offer an affordable way of applying foil on paper and fast changeover to switch back to putting ink on paper.

Two major press manufacturers —Heidelberg and MAN Roland—have recognized the demand for specialty foil effects and now offer presses with cold foil units built-in, setting atop of a press units. U.K.-based OFT Technology also provides units—distributed in the U.S. by American International Machinery (AIM)—that can be retrofitted into existing presses. OFT's Foiltone system is used by press makers KBA and Mitsubishi. To date, AIM says it has signed up four retrofit customers.

Unlike hot foil systems, cold foil is an inline process and does not require heat for transfer nor expensive dies to define the design. Instead, cold foil systems are made up of two units: one unit of the system applies an adhesive that defines the imprint for the foil, and the second unit releases the foil from a carrier sheet and applies it to the substrate.

Registration issues, regardless of how delicate, are the same for cold foil as for trapped or overprinted ink on ink. The printing plates used in the process are the same as those used in conventional offset printing. No special makeready is required for the process.

Cold foil offers printers a range of colors and effects. The foil accepts overprinting of halftones and a full range of metallic colors using standard inks and varieties of foil to achieve the desired effect. Range of coverage is from the smallest font reverse-outs to full-sheet solid coverage.

Indeed, hot foil is the legacy technology for comparing foil systems. Hot foil systems have been used for years in the converting market, where shiny bits on packaging help sell products. Hot foil stamps satisfy the need for special effects like holograms, security tags, unique identifiers and 3D embossing.

However, historically hot foil stamping and embossing has been an expensive and time-consuming process. It requires additional staff to operate machinery, is a several-pass process and uses specialized machines for diecutting, embossing and hologram printing that occupy equipment investment and the slow throughput of the multi-pass process. These factors have kept hot foil out of high-speed commercial printing.

Cold foiling boasts many advantages, but there are disadvantages. Process downsides, say industry observers: heavy rolls of foil, inability to index, flat foil can be applied only to coated paper substrates and the foil substrate is not stamped into surface—resulting in a lower sheen than if hot stamped. But, when weighed against the benefits of high-speed press throughput—full foil coverage, pre- or post-print application, overprinting and halftones, textured applications, no substrate distortion, no die cost, low energy requirements, fast makeready times, no additional staff requirements and near elimination of registration problems—the process seems to be a net winner.

Not all hot foil effects, such as holograms and 3-D embossing, can be replicated by cold foilers, but vendors say those capabilities are coming. Requests for foil as a packaging option, highly regarded as a security tool, is moving beyond converters and into commercial printing plants.

For print customers, the cold foil option broadens the palette of design options. The same rationale that is used for including foil in packaging—increasing product sales—will one day be applied to flyers, magazines and books. Because foil can be treated like a color and integrated into a design, designers will be more likely to use metallic colors, without the fear of complicating or delaying the print run.

Besides the range of colors available in foil, designers can specify foiled jobs overprinted with halftones or solid and process colors. Hot foil stamping typically requires a base material where the first layer is a silver-colored aluminum that is vacuum-metallized onto the base foil, and a second layer that often is the colored coating for the aluminum base. This means that the printer must restrict the range of colors available or order the color foil on a job-by-job basis.

For the hot foil printer, the net result is carrying many different rolls in inventory. For the designer, it means avoiding the use of foil in cases that do not absolutely require it. But with cold foiling, there is no restriction on the number of foil colors used in a job, opening the door to a new range of visual effects.

Three cold foil solutions are on display at this month's Graph Expo show in Chicago. AIM, the exclusive North American dealer representing OFT Technology (Booth 253), Heidelberg (Booth 1200) and MAN Roland (Booth 646) are showing presses to which cold foil systems can be integrated.

OFT Technology introduced its Foiltone one-pass foil embossing system to the sheetfed market about a year ago. Since then, the firm installed 30 systems and predicts another 100 will be sold in two years. The system can be fitted into most sheetfed presses.

OFT's approach works like the others, the first unit of the system prints an image in glue, using a standard offset plate imaged in a normal way— this is how the process avoids using dies. The sheet then passes out of the first unit and into the second. Mounted over the second unit is a foil unwind that uses a direct-drive servo to feed foil down into the unit, around the blanket cylinder and exit it at the back, where it is rewound onto another axle mounted over the unit.

When foil is not being applied, the units can be used for their original printing application.

The Foiltone module consists of four axes that enable two webs of foil to be run without being invasive to the press. Protective varnishes are not required, but can be added in addition to overprinting.

If there is any bad news, it is that the Foiltone system—and other available systems—takes up two units of any press it inhabits during a foil run. This can be two print units or one print and one coating unit. The placement of the system on the press determines the effects that can be created. For example, in a Foiltone system placed in the post-print location of the last print and first coater unit, the applied foil will look like a hot foil stamp. If the system is placed on the first two units of the press, inks can be registered to the foil or the foil can be overprinted.

At Graph Expo, Heidelberg is exhibiting its FoilStar cold foil module, available for Speedmaster CD 74, CD 102 and XL 105 presses.

Cold foil is applied in the FoilStar system through two conventional offset printing units. The first printing unit uses its inking unit and a regular offset plate to apply an adhesive to all or part of the sheet. The second unit—the actual cold foil module—is equipped with take-up and take-off units for applying the foil. The foil is “nipped” together with the sheet between the blanket and impression cylinders, and the pressure transfers it to the adhesive-bearing areas. When the backing is removed, the metal layer remains behind. Both printing units can be used for printing immediately after the cold foil application, which represents great potential for fast makereadies.

The foiler now offers the capability of processing cold foil with up to six variable web widths. The system is capable of applying high-quality, foil-based metallic finishes to all kinds of printing stock in weights of 70 to 400 gsm. Cold foil as an inline application on the presses is achieved at printing speeds up to 15,000 sph with excellent register. Even though high speed is a key reason cold foil is making inroads to the commercial printing world, the quick makeready and reduced processing time as an inline application makes it equally useful for short runs.

MAN Roland is showing its InlineFoiler Prindor, a 2006 InterTech Technology Award winner. The cold foiling system was first shown at last year's Graph Expo as part of the Roland 700 press. The foiler can be installed on two printing units of any recent 41´´ 700 model. Those unitscan also be used for regular offset printing. MAN Roland says changeover from foil to regular printing takes 30 to 60 minutes.

Because two printing units are required for foil transfer, the company recommends at least a 6-color press for the inline foiler. The first printing, like the other cold foil systems, applies a special adhesive ink via the inking roller system using a conventional printing plate. However, this adhesive ink is colored so that the amount applied can be measured by a densitometer. A foil unwinding station is mounted on the second printing unit; the blanket cylinder presses the foil onto the areas of the sheet covered with the adhesive ink. The unused foil remains on the carrier layer, which is rewound on a rewinding station above the third printing unit. In this printing unit, and subsequent ones, the areas of the sheet not covered with foil can be printed with absorption-drying inks.

The process now allows for multiple rolls, which means shades of silver, gold and diffraction-patterned foils can be mixed and matched.

In addition to the cost savings realized from the inline process, MAN Roland stresses that many color and printing opportunities can result from “flat” foil on a substrate and the ability to overprint without additional passes. Meanwhile, overprinting with offline cold foil units requires a second pass—and embossing or stamping with hot foil doesn't allow for overprinting.

MAN Roland claims that overprinting with conventional, UV or hybrid inks improves the adhesion of the cold foil ink, and conventional ink films have to be coated because of the slightly delayed drying of the ink films on the transfer foil. The company reports it has obtained exclusive patent rights for this economically and technically advantageous combination process of inline foil transfer and subsequent overprinting.

The overprinting technique was used to produce GAM's July 2006 front cover. (See it in “AwardCentral,” p.95.) Silver foil was applied and then over-printed with 4-color process inks to create a dramatic, highly glossed golden effect. Aqueous coating was added over the 100-lb. matte cover stock.

Besides the flat applications mentioned earlier, this also means 3-D embossing. MAN Roland has applied for a patent on the combination of “cold foil transfer and 3D embossing in one.” This patent is in addition to six other patents it is seeking in this area.

ONLINE: www.aim-inc.net, us.heidelberg.com, manroland.com and oft-technology.com