The letterpress process has been a cornerstone of high quality reproduction in the foundation of the printing industry for more than 100 years. It is the parent of all contemporary high-volume printing processes, and has evolved over the years from the use of platens to flatbed cylinder presses to rotary letterpresses.
In the narrow web converting industry, letterpress today is not enjoying the popularity it once had. It remains a process that delivers extremely high quality in image reproduction, and continues its challenge to offset lithography in such industries as wine label printing. The reason for its struggle today, especially in North American markets, is not offset, however, but UV flexography. The continuing refinement of UV flexo presses and their attendant ease of operation present a serious challenge to this respected and time-honored process.
"Rotary letterpress today is not really popular," says Jerry Nigg, North and South American sales director for Ko-Pack International, the Japanese press manufacturer. "Around 1980 rotary letterpress made its way into the United States and Canada from Japan and Switzerland, and was acquired by the 15 to 20 percent of the market that wanted to achieve higher quality labels. It still does just that," he adds. "It's not a forgotten process. The process has made its way into specialty printing versus everyday common labels."
Rotary letterpress muscled its way successfully into the wine label printing market because it offered advantages over traditional sheetfed offset printing. In the sheetfed process, several passes through various machines might be necessary, for printing of colors, application of foil and/or embossing, and diecutting. Adhesive is applied as wet glue in the label application process, and specialized shapes are not always possible. Rotary letterpress reduced all of those processes into one machine that handled them inline, with a finished, adhesive-backed product wound on rolls at the end of the press.
Older generation letterpress processes required considerable makeready times, but with the advent of rotary letterpress that drawback changed. Letterpress practitioners today maintain that the process even has advantages over setting up and running flexo.
"The initial setup time is probably the same, but getting going and running is much shorter," says Don Ingle, president of Best Labels, located in Cerritos, CA. "I can take any four-color process job, set up and run it before you figure out on flexo what anilox roll you have to use."
Fast job changes
Best Label's strength today is in the nutraceuticals market, as well as in automotive and cosmetic labeling. "We do a lot of short run printing — 5,000 to 10,000 labels — in four color processes. As long as we have good prepress and plates, we can adjust the ink with keys and make it look as close to offset as anything," Ingle says. "To do this with flexo, you have to change the anilox roll to 1,000 line, then go to 400 line, back and forth to get the color you want. With letterpress you just do it with an ink key. Put a job on and run it and get it over with, well before you've decided what anilox roll to use in flexo."
Still, says Ingle, UV flexo is giving letterpress a run for its money. "If I went back to 1983 and I was looking for a press, and if flexo then was as good as it is today, I don't think that letterpress would get a hold in the US market," he says. "When we first started, customers wanted letterpress. Today, in all honesty, flexo can do it as good, but the short runs I can do a lot faster with rotary letterpress."
Best Labels has seven Gallus letterpress machines, plus one Arsoma UV flexo press and an Arpeco press.
Ink train
Letterpress technology is between offset and flexography in its design. The inks are more viscous than those employed in conventional flexo. Ink is released onto the ink rollers via keys, identical to the offset method, which offers a significant mode of control. The ink is then transferred to plates only after traveling between and among several rollers in the ink train. This is done to spread the ink to the right depth for transfer to the plates.
"The inks are thicker when they go into the press, but thinner after they travel through the metering rolls," says Bob Yates, West Coast sales manager for Gallus Inc., based in Philadelphia. "The ink is actually thinner than UV flexo ink by the time it reaches the plate." Ink laydown on a UV flexo press ranges from two to five microns; conventional flexo ink is from one to 1.5 microns; rotary letterpress ink ranges from 0.75 to one micron, and on offset presses the ink thickness is from 0.5 to 0.75 microns.
Letterpress plates, like those used on flexographic presses, have a raised image, but they do not feature the pliancy that a flexo plate has. Photopolymer letterpress plates are stiffer and thinner than those used in flexo, and on press the impression is somewhat stronger.
"There is less dot gain than there is using a flexo plate," says Yates, "and less distortion on the plates themselves. The relief area is half of what it is on a flexo plate." But that's changing, he adds, noting that flexo plates are beginning to get thinner. "Those two are coming closer together.
The smaller dot gain offers advantages to the converter faced with reproducing a difficult vignette. "On a rotary letterpress, you can adjust the print heads and tweak the keys to come up with color matches faster, and without having to change anything within the press. And it takes less setup and produces less waste," Yates adds. "The plates are out and in and tweaked in 30 minutes. The biggest job on a flexo press is getting the color match right."
"Compared with flexo, letterpress has very little dot gain," says Ray Kapoor, president of Spectrol Label, Mississauga, Ontario. "That gives a sharp and detailed image, especially if you're doing process work. Every detail is covered. It's more expensive than conventional flexo, but high end manufacturers, and pharmaceutical companies, prefer to use letterpress. Customers in high end markets don't mind paying a penny more," Kapoor adds, "especially the liquor companies and the cosmetics companies. They get a better shelf presence for their products."
Kapoor, whose company prints using four Gallus letterpresses and one Arsoma UV flexo press, says he has always preferred letterpress. "If you compare [against conventional flexo], the image is distinct — a very precise, distinct quality. UV flexo is between flexo and letterpress, but that gets expensive, because the inks and the machines are costly. The finished product comes maybe 85 percent closer to letterpress, but it's still not there."
More training is required to operate a letterpress machine, Kapoor adds. "You have so many keys to play with, and you can make so many corrections, but you also have more control."
Various constructions
Letterpresses vary in construction, from inline to central impression (CI) to stack versions. Moreover, the technology comes in a semi-rotary process, where the web moves and stops so that the cylinder re-registers.
"In our machine, the cylinder rolls continuously, and the web goes forward for the repeat length and then slows down, goes backwards, then forwards again," says Pierre Panel, export sales engineer, North and South America, for Codimag, manufacturer of printing presses based in Bondoufle, France. Half of Codimag's presses are letterpress, Panel says, the other half featuring the company's waterless offset technology.
"What makes letterpress still viable in some markets, especially for semi-rotary, is that you don't change cylinders, so the setup time is much shorter than it is for UV flexo," Panel says. "You get vignettes down to 2 or 3 percent, and have good control of the ink with the keys. That's the advantage of letterpress printing without the drawbacks of tooling and long setup.
"If letterpress is decreasing in the marketplace," Panel declares, "it's mainly rotary letterpress. Semi-rotary still has advantages over UV flexo."
Letterpress is a small market in the US and Canada, say the manufacturers, but Europe has been, and remains, devoted to the process, as do the Japanese label converters. It appears, also, that Central and South American converters favor the process.
"Letterpress is popular in South America," says Jerry Nigg of Ko-Pack. "We just sold a CI press to a company that produces in-mold labels. The CI drum holds register, and the film doesn't stretch. The end user wants offset quality, and they couldn't go flexo and achieve that quality." Ko-Pack also makes an inline letterpress.
European strength
"Letterpress is stronger by a factor of five in Europe than in the US," says Ferd Ruesch, chairman of Gallus. "Sizes are significantly smaller than in the US, and they demand color consistency. The ability to maintain color consistency is extremely high with letterpress. In Europe, letterpress is still slowly growing."
In North America the letterpress market is flat, Ruesch says. "A few big companies, like Sancoa, know precisely when and where to use letterpress to make the most money on their product. They understand their businesses extremely well, and they have the perfect applications to use traditional letterpress, with less waste in substrates and inks. Letterpress still has a very dedicated market."
