A nice newspaper press

[Doug Kerr]

Some wag once said, "Freedom of the press is only significant to someone who has one". Here, we report on a visit to somebody who does.

Our local daily newspaper is the Weatherford Democrat. Don't be misled by the name - it goes back to the time when (here in the South) the conservative political party was The Democratic Party. The paper leans a bit to the right (as befits the community), but not outrageously so.

The paper held a reception last Thursday for their new editor, a young woman born in this area who has been in the newspaper business almost all her life, most recently as Metro Editor for the Camden (N.J.) Courier-Post.

While Carla was discussing with her the need for enhanced coverage of local social and cultural activities, the publisher invited me to tour the printing plant.

The centerpiece is an 8-unit Goss Community-series web offset press, built in 1974 (when Goss was a division of Rockwell). It is set up to produce up to a 20-page edition with four pages in full color. Here we see the press from the "black end" (one unit is out of the frame to the left - we'll see it later).

Douglas A. Kerr: 8-unit Goss Community press - black end​

The units are equipped for a "22.75" cutoff", meaning that the circumference of the plate and blanket drums is 22.75" and thus they produce a page 22.75" long (that is, high). The paper's page size is 11.00" wide, and the press units are thus fed with web stock 22.00" wide. (The 11.00" x 22.75" page size is very popular for papers today.)

The units each have two sets of plate and blanket cylinders, and print on both sides of the web. Thus (with the 22" web), each cycle produces four pages.

(This is called the "single-width" arrangement. Bigger papers, with larger presses, use a web four times as wide as the page. The web out of each unit is split lengthwise on the fly into two webs, which are then shifted into alignment as part of final assembly.)

We see that the second unit in this frame is fed with half-width web stock (11" wide). This produces a two-page sheet (you know, the ones you cuss when you are disassembling the daily paper to get paper to lay down on the patio floor when you are spray-painting the patio chairs). As you can see, the black end is producing four webs (including the half size one). Normally which will be accompanied by a full-color four-page web (produced on the other end of the press), for a total (for this particular setup) of 18 pages in the edition.

Here we see the color end of the press:

Douglas A. Kerr: 8-unit Goss Community press - color end​

We see that two units are "stacked", forming a "tower".

The leftmost of the units does the "blue" (cyan) impression, the next unit the "red" (magenta), the bottom unit in the tower the yellow, and the top unit in the tower the black. (What we see here is left over from the run of an insert for the Sunday edition, and the pages are in fact laid out "crosswise".)

Note that the web here takes a roundabout route before actually entering the blue unit. This is to allow the paper to fully "relax" from its tensioned state on the roll before it enters the unit. If the relaxing were not complete by that point, it could lead to registration problems. Along the same line, the web supply spindle here is equipped with an electronically-controlled hydraulic tension brake to maintain the actual tension on the web constant as the roll diameter decreases. (A much more primitive tension brake is used on the units at the black end.)

On the left of the frame we partially see the folder, a Goss SC-series. The multiple webs are overlaid and then jointly creased down the center by turning down over the edges of a polished triangular "sail". A set of rollers flatten the resulting "gutter fold". Then the papers are sheared (22.75" long) and a second stage makes the final fold (the one we are so anxious to get our pix "above"). They come out on a set of conveyor bands overlapped ("shingled").

This folder also has a "quarter-fold" mode used for the special format with the pages laid out "crosswise" on the web (sometimes called the "tabloid" format).

Here we get a better look at one of the units on the black end (number 1, in fact, not seen before):

Douglas A. Kerr: 8-unit Goss Community press - unit 1​

The "thermometer" dial just to the left of the red button is a tachometer showing the speed of the press. All the units at one end are driven by a large motor located near the folder, through a horizontal shaft behind the units (it is in a gray housing, and can be seen in the "color end" picture).

The paper rarely runs an edition of maximum size, and so often unit 1 is not used (maybe not 2 either).

I'm trying to arrange to go to the plant wile a run is being set up and started. I'm sure I'll learn a lot more then.

Sadly, the wonderful smell of an old-time press room has mostly disappeared owing to the more environmentally-friendly new ink recipes and the use of safer solvents than gasoline for cleaning!.

Perhaps soon this entire mode of information distribution will be extinct.

Best regards,

Doug

 

[Ruben Alfu]

Fascinating reading for me to enjoy in this relaxed Saturday morning, great pics, thanks for sharing Doug!

 

[Asher Kelman]

This is impressive. One can buy such units for 30 cents on the dollar used as dealers harvest the older presses as companies upgrade. You just need a team to service the thing!

Asher

 

[Doug Kerr]

I thought I might talk a little about a fascinating collateral aspect of serious newspaper printing.

Typically, at the production rates involved there, a roll of web stock paper can exhaust in as little as 10 minutes (the web may be traveling at up to 40 mi/hr).

Most serious press lines have provision for substituting new rolls on the fly with a system known as a flying paster. I was fortunate to find this nice video of a paster "firing" on YouTube:

http://www.youtube.com/watch?v=mAvUA7UGlDI&feature=related

As the scene opens, the roll that is finishing up is at about 3 o'clock (hard to see) on the three-arm carriage. The incoming roll is at about 11 o'clock. The next roll up is at 7 o'clock.

The blue stripes are double sided "web splicing tape", placed right at the free end of the web (which is now only lightly stuck to the layer underneath). The small rectangular tabs (sometimes they are black) are markers that allow the system to track the phase of the roll in preparation for the join. Today, it is required that both all this be "repulpable" so that they do not poison the plant waste, which is recycled into paper pulp.

When the outgoing roll gets near its ending diameter, the carriage is rotated to put the incoming roll into position for the transfer (about 12 o'clock), and the system begins to rotate the incoming roll, bringing its speed to where its surface velocity matches the velocity of the web. (You will be amazed to see how fast that looks - remember, the web is perhaps moving at 40 mi/hr.)

Then, when the outgoing roll reaches its critical end diameter, when the incoming roll is next at the proper phase, a roller hops in to slap the web onto the incoming roll, where it sticks because of the blue tape and pulls the free end from the roll. At the same time, a blade cuts through the web coming from the outgoing roll, which is now out of the picture, and the web is now being pulled from the incoming roll. (We can't clearly see either the roller or the blade, but we can see the dead tail from the outgoing roll flop down.)

The outgoing roll is quickly braked to a stop so the tail from it does not flop around.

Then the carriage is rotated to being the almost empty outgoing roll core to the 7 o'clock position so it can be removed and another new roll put in that spot.

The new roll is has already been prepped at an earlier station with the blue tape and black markers, so it will be ready to play its role when its time comes.

This rig is in the "basement" of the press room. There is one for each unit (or multi-color group). These presses almost always operate on a "double-wide basis", so for a press line with a maximum edition size of 48 pages, there would be six of them.

It is all way amazing.

Best regards,

Doug

 

[Asher Kelman]

Is the latest technology just computerized and essentially the same?

Asher

 

[Doug Kerr]

Hi, Asher,

Is the latest technology just computerized and essentially the same?

Yes. In fact, the flying paster in that video is highly computer-controlled.

One of the recent changes is the way the offset plates are made. (Assume that each case that the page composition is done entirely by computer).

Until fairly recently, a "film writer" with an RIP (raster image processor) and a CRT-based exposing engine made full-size film negatives. These were then used in a "contact printing" context to expose the offset plates themselves. (This is how the Weatherford Democrat operates today.) This is called CTF (computer-to-film) operation.

In the more modern process (called computer-to-plate, or CTP), the offset plate itself is produced by a special "printer" using a thermal process. (The Democrat will be moving to that later this year.)

Typically the page images are fed to either the film writer RIP or the plate writer in either PDF or TIFF form (the drift being to PDF).

Best regards,

Doug

 

[Doug Kerr]

Although offset lithography is by far the most widely-used printing process today, some readers may not be familiar with its principles, so I thought I would review that.

The process depends on the legendary opposition of oil and water. In this case, the ink plays the role of the oil. In fact, until recently, the ink was oil-based. Now, for environmental reasons, it is not, but its chemistry makes it behave like oil in the way that is important here. (What is involved is actually a difference in surface tension.)

Before we proceed, recall that this is not a gray-scale process. At each point on the printed page, ink is either deposited or not. "Modulation" of the effect of the ink is done by the halftone process. There, any area not "dead black" (or the equivalent in another subtractive primary, for color printing) is composed of multiple small dots whose diameter (and perhaps spacing) is varied. The resulting average density of ink determines the reflectance of the area.

The printing plate is a thin metal sheet whose surface, at any point, has one of two properties. I will speak of "black" and "white" areas for convenience.

The black areas "like" oil, and "reject" water (they are said to be oleophilic and hydrophobic). The white areas "like" water, and "reject" oil (they are said to be hydrophilic and oleophobic). Note further that oil itself is hydrophobic - it does not like water. And vice-versa - the stuff of classical metaphors.

The plate is wrapped around a revolving cylinder in the press. On each cycle of the press, the plate first passes a "station" in which is it offered water (called the "dampening" process). The white areas take on a thin coating of water, but the black areas do not, because of their respective appetites regarding water. The water has thus "amplified" the oil vs water preference of the plate surface - hydrophilia in the white areas leads to enhanced oleophobia there.

Next, the plate passes another station in which it is offered ink. The black areas take on a thin layer of ink; the white areas do not (not only because they are by nature oleophobic, but even more because they are now bearing water, the arch-oleophobe).

Next the plate is brought into contact with a rotating cylinder having a rubber-like coating (the "blanket"). The ink transfers to the blanket. The water is squeezed away in the process.

Then the paper stock is brought into contact with the blanket cylinder (squeezed against it by a metal "impression cylinder") and voilà - we have printed. It is the role of the blanket as intermediate carrier of the ink image that is responsible for the term "offset" in the name of this process. (In "classical" lithography - not used in modern printing "presses" - the ink goes directly from the "plate" to the paper.)

If the unit prints double-sided (as in the typical newspaper press), the paper is squeezed between two blanket cylinders (each carrying the image from a separate plate), and there is no impression cylinder.

Best regards,

Doug