Going to a press check is no pleasure jaunt. You may have to travel all day by plane and all evening by car to get to your printer’s location. If you are scheduled to see color at midnight, it may be 3 a.m. before you get the call from the printer that the color is up.
Happily, once the pressman is ready to have you approve color, there are things you can do to make the actual press check go smoother.
First, make sure that the printer is running the correct paper for the job. Look at the manufacturer, weight, and quality information stenciled on the label of the paper roll’s kraft paper wrap to ensure that it is the paper you ordered. Ask the pressman if he had any problems running the paper or if any was damaged in transit. You should have already received confirmation that the paper arrived at the printer, a report on the condition of the paper, and the bill of lading to compare against the invoice.
Next, you want to make sure the press is in register. Other than the obvious blurry image, the best way to inspect registration is to look for “hanging color” off a two-color bug or display type. At the bottom of the large type or color panel you may see a faint line in yellow, magenta, or blue, depending on the color makeup. This colored line results when the press is out of register.
To check whether the black plate is out of register, find an image with a drop shadow (because shadows should be made up only of black). Look at the point where the shadow meets the four-color image. If you see a thin white gap, the black is slightly out of register.
Offset press proofing
Offset press operators get to the color by “the numbers,” using the standard web offset press (SWOP) guides. They will follow the guidance on the proofs that the separator has provided, adjusting for densities and paper stock, and then they will go over the supplied proofs and match the color image by image. They will then call in the client to approve the color.
Offset presses apply ink from a fountain onto ink rollers in a strip about one inch wide from top to bottom of the page signature. The press operator manipulates the color through buttons or ink keys that control the ink fountains by adding or subtracting cyan, magenta, yellow, and black (called key).
Because multiple images may be affected by manipulations from the same ink fountain — and may need opposite color changes, or moves, to match the proof — you’ll find yourself having to make tradeoffs regarding color accuracy. If you have one image on top of the page that is too magenta and an image below it that needs magenta, you’ll need to strike a medium with neither image at the optimal color. Or you may choose to give the hero shot the optimal color move, sacrificing the color on another product.
Color matching is a slow and deliberate process. You start with one image and determine if the color is acceptable, then move down the form to the next image. If you contemplate a color move, you need to take into account its effect on each image in the line.
Coloring your world
When checking color, first determine if the image is washed out. If it is, the quick fix is to increase the three color inks, cyan, magenta, and yellow. Then look at the blue: Is it too red, too green, not blue enough? Repeat this process for each color. With yellows, it’s easy to see the color moves needed. Light wood and flesh tones have 3%-10% dots of yellow and red, with a touch of cyan to create natural browns. If the skin is too red, cut the magenta; if the skin is too jaundiced, cut the yellow. Conversely, you can use yellow to cut red and red to cut yellow.
Bright colors and dark images usually don’t present a problem on press. The difficult colors are greens and purples. There are no secrets to capturing them; sometimes you get them right away, and sometimes you chase them all night.
Also check to see that the whites have body, with shadows and lines. If your images lack detail, add black. Look at the shadows: If they are too light, add black; if they are too dark, cut black.
You’ll need to recheck your blacks once you have the color to the desired level. Review the type closely for readability. Sometimes as you pull back on the black ink in an image, you inadvertently reduce the black type to gray. Look at any large display type that is pure black to see if it has turned gray. On the flip side, you may have added so much black to an image to pump up the detail that the black type is bleeding. You can see this with small caption or body type that has lost its crispness.
Once you are satisfied with the color, sign off on the forms and get a few press sheets to compare with the bindery samples.
Rotogravure press checks
One main difference between rotogravure press checks and offset is that most gravure forms have more pages. The other difference is that the marking is not done “press side.” Because you must make the changes instantly, you view gravure color in a viewing room.
There are two moves you need to consider with gravure: global ink moves and individual image manipulations. The process for gravure and offset starts the same: You look at individual images for color fidelity. But gravure ink fountains are not manipulated by ink keys; rather, the cylinder is partially submerged in the inkwell, and the ink is applied uniformly across the paper. The ink is directly transferred from the cylinder to the paper, and there are no color tradeoffs with images in line.
After reviewing a few pages, look back at your marks to determine if there is any pattern of one consistent ink move. If so, skip ahead and see if you could globally cut an ink with thinner or add more ink to get better color. A good global move will be quick and may resolve many of your color issues.
After you have reached a balance of ink and thinning solution, examine the color image by image. You will work through the complete form and then stop the press and make the changes on the cylinders directly, deepening the cells or engraved image for a color add and reducing the pits for a color cut. After you make all the changes to the cylinders, they’ll be remounted on the press for another round of color moves.
This is a long and expensive process, so be decisive and make your changes the first time. A second or third round of reworking the cylinders should be required only if the etchers missed the color moves.
Below, a few more specifics to watch for on any press check:
Hero or lifestyle shots set the theme and bring together two pages into a cohesive spread. As most catalogs are composed of multiple press forms — body forms, wraps, or covers — there will be times when a hero or lifestyle image spans across the gutter and prints on two forms run at different times, on different presses, or even at different printing plants.
To ensure that the color matches on both forms, identify these crossovers and match the color. Since you can’t go back and color-correct a completed form, you will need to live with the color match for the current form.
- PAPER FOLDS
Pay attention to the folds and have the pressman make adjustments, if necessary. Review each fold to ensure that the press is correctly set to give a crisp fold in the exact location desired. The most obvious bad fold is a cover image that extends into the spine and shows slightly onto the back cover. Also, a badly folded book will make crossovers on the inside pages appear broken up.
- WEB BREAKS
During printing, the roll of paper may break, causing the presses to stop. Defects in the paper itself, ink that is dry and tacky, and too much tension on the paper roll can each lead to a web break.
Scumming occurs when the plate begins to dry due to an imbalance of water and ink. It begins at the edges and creeps toward the center if not caught. The scumming will appear in the white areas as weak, almost pastel colors streaking across the pages. To remedy the problem, the press operator will add water.
- BLANKET SMASH
A blanket smash happens when a piece of paper or a foreign object has dented one of the rubber blankets that transfer the image from the printing plate to the paper. The indention cannot transfer ink, so an ink void appears on the paper.
The easiest way to spot a blanket smash is when an odd-shaped area on an image appears in one color. This smash moves around slightly with each impression, traveling across the image at the rate of the difference in size between the plate drum and the blanket drum, always in a top to bottom direction. The only fix is to stop the press and replace the blanket.
A blanket smash is rarely visible on the yellow blanket, because a void in yellow is hard to see. If it is on the cyan or magenta blanket and moved off an image into the black type area, the pressman will want to hold off on the press stop until it works its way to the next image. If it is on the black blanket, it will affect both the type and the images: The type will disappear, and the images will not have detail.
A moiré appears when the dots that make up an image create a wavy pattern. This problem cannot be fixed without stopping the presses. And because the problem is rooted in the prepress, the printer will not foot the cost of the downtime.
If the moiré is minor, you may want to keep the presses running while the prepress house fixes the problem and the printer burns new plates. If the pattern is unsightly, then you will need to stop the press and wait for new plates. Mostly a moiré occurs in images of fabrics or screens in windows or fireplaces. Also, a moiré may appear if an image is a scan of a previously printed image and the previous dot pattern has not been removed or descreened, or if the angles of the dots are too close.
Moirés are typically eliminated by the prepress house setting the color film screens at different angles. They should be caught at the proofing stage by close examination of problem images. If the moiré does make it to the plate, the printer’s prepress department can sometimes reburn the plates at a slightly altered angle. The conventional 3M Matchprint and the digital Kodak Approval color-matching proofs both have a dot pattern that will show the moiré as it will appear on the press; the stochastic 3M Iris proof, however, will not show these patterns, so they may appear on press.
If the press form has wrinkles, the folders are too tight. The press operator needs to release the folder tension to stop the wrinkling.
- HICKEYS (also called halos)
A hickey is a small bubble or obstruction on the printing plate that appears on the printed piece as a small circle, generally in large fields of heavy color. Because the hickey is on the plate rather than the blanket, it does not travel like a blanket smash. Every book will have the hickey in the same spot until it is wiped off or the bubble pops and disappears. The pressman will remove the hickey by taking a spatula to the running press and wiping off the particle, or by washing the blankets.
A thin line that goes from top to bottom on the printed piece is called a ring-around. Typically caused by a small wad of paper or other abrasive that wears away the soft blanket, a ring-around can be fixed only by stopping the press to replace the worn blanket. The printer is responsible for the expense of this press stop. The press operator can avoid wearing out the blankets by removing foreign material with a blanket wash — a periodical cleansing of the blankets — during a long press run.
- CRACKING PAPER
Sometimes when you pull a press proof, the paper will be stiff and cracking, perhaps due to overdrying in the heaters. A heat-set press will dry the ink in an oven before the paper signature is slit and folded into its final form. The paper can become dry and brittle and even catch on fire, causing the roll of paper to break. Either the oven temperature needs to be lowered, or the speed of the press needs to be increased.
Remember that press checks are not just the art of matching color; you must address several mechanical issues to get the best product. While production technology has greatly reduced many mechanical and color problems, it is still important to be aware of the root causes and possible solutions to get the press running and achieve the best product possible.
Timothy Gable is production manager of The Children’s Group, a Rohnert Park, CA-based subsidiary of multititle cataloger 1-800-Flowers. Russ Goin is production manager of Chicago-based gifts cataloger Hammacher Schlemmer.
Press Check Checklist
- Registration: Are the plates in register?
- Color: Does the color match that of the proof?
- Crossovers: Did you identify and compare crossovers to be sure the colors match?
- Gray blacks: Is the type hard to read? (If so, increase black ink.)
- Bleeding blacks: Is the type fuzzy and very dark? (If so, cut black ink.)
- Folds: Are the folds correct and crisp? (If not, adjust the plow.)
- Scum: Is there excess color on white areas? (If so, adjust the water-and-ink ratio.)
- Blanket smashes: Is there a loss of color in image? (If so, stop the press.)
- Wrinkles: Is paper wrinkling when folded? (If so, adjust the folder tension.)
- Hickeys: Are small dots consistently appearing on page? (If so, wipe debris off the plate.)
- Ring-around: Is there a thin line appearing through the page? (If so, stop the press.)
- Cracking paper: Is the paper stiff and crackling? (If so, lower the temperature on oven or speed up the press.)
M1000 and M3000: What’s the Difference?
On the M1000 heat-set web offset press, the signature form (the printed sheet after it is folded) is two pages high, four pages wide, back and front, for a total of 16 pages. The M1000 has two rolls of paper, or webs, making it 32 pages out. The M3000 signature is two pages high, six pages wide, back and front, for a total of 24 pages. The two webs feeding the M3000 deliver 48 printed pages.
Registration Made Simple
The traditional method to check print registration has been to align marks in the four process colors by slightly adjusting them manually until all four marks converged, or “registered.” Then the operator would continually check the alignment to keep the marks in register. In the past, this was tedious and time-consuming with fairly inconsistent results. The process has now been automated, however, with a “closed loop” system consisting of a computer-controlled photoelectric eye that tracks and automatically keeps the color in register.