Newspapers and Technology March 2000
Readers respond to registration issues
By Ray Reinertson
Please submit questions in the broad area of newspaper print production that could include prepress, plateroom and pressroom to Ray Reinertson at Rreino@aol.com.
In the January issue, Ronnie Poon, assistant vice president of prepress for Singapore Press Holdings, presented a question that resulted in three responses. I'll repeat the question and you can read their e-mails.
Q: We transmit the CMY separations way ahead of the black so as not to create a bottleneck on imagesetters and plate making lines. This often results in the black not getting in perfect register with the other three colors. What do you suggest?
A: As you stated, the best scenario is to always send all color separations to your imagesetter at the same time. As long as the imagesetter goes through regular periodic maintenance and is in good working order, this will provide excellent output each and every time.
If the workflow doesn't allow for this, then the issue may be dependent on the imagesetter being used. Usually drum imagesetters should be able to handle this task just fine. One of the reasons for this is the media being imaged is stationary and the laser moves along a shaft and images the media.
With capstan imagesetters, the laser is stationary and the media moves. Since the media is roll fed (like a web press, only much smaller) there is more resistance to the media movement at the beginning of a roll of media than at the end of the roll of media. If the CMY plates are imaged at the beginning of the roll there is a likely chance that if the K plate may have registration issues if imaged further into the roll.
Another good way to avoid these issues is to ensure that the imagesetter being used has a built-in punch. With this mechanism and a transfer punch/trimming combination table from Stoesser, any piece of media can be aligned properly. There is another benefit with this workflow scenario in that the production time can be decreased due to efficiencies in punching and trimming the media.
While you can also use transfer punch/trimming tables with imagesetters that do not have built-in punches, the accuracy will not be as great and you may have some registration issues. Perhaps this lends a clue to what is happening.
Mark Astmann
Director of Product Development
Servador
A: At the Providence (R.I.) Journal Co., we also transmit the CMY much earlier than the K. The way we solve registration issues is to make sure that our pages "lock" on the same imagesetter and therefore use the identical one to avoid registration issues.
This is based on using a transmit and receive server that the files spool to after being ripped. The transmit and receive servers act as a "traffic cop" for our imagesetters, knowing which imagesetter the files have gone to. When they see a specific file name that matches a previous file name, they traffic the file to the same imagesetter.
We have three different imagesetters for film and this works well. Stringent file name conventions is what makes this workflow successful. We have a Monotype open prepress interface system and the configuration works like this: OPI to RIP (4 of them) to transmit server (1 in main building) to receive server (1 in printing plant) to ROPs (these hang from the output devices and manage the data going to the imagesetters) to imagesetter.
Hope this helps Ron Poon. Let me know if I can explain anything further.
L. Natale
Assistant Director of Operations
The Providence Journal Company
401.277.7693
lnatale@projo.com
A: We have been sending color separations ahead of final black for the past three years to cut down the bottleneck on platemaking. Here's how we do it.
Our paginators (all editorial people) will put the photos in place on the page along with some text. When they send the separations early (before the final text has been edited or corrected) they send all plates, CMYK. The camera department lines up the color negatives to the initial black negative and begins to plate the color. We then cut a Rubylith mask to cover any and all text on the page. We then burn a black plate with the mask and set it aside. When the paginators send the final black to the imagesetter, they remove all photos so that the page only contains text.
We then line up the final black negative to the initial black negative and double burn onto the previously burned black plate that we had set aside. We do send the final black to the same imager as the color separations and initial black negatives for the sake of consistency.
Howard K. Droegemeier
Operations Manager
The Hays (Kan.) Daily News
There was a Y2K glitch in the January column. The response on registration said that at 100 lpi a row of dots is .0001 inch out of register. This should have been .01 inches.
Ray Reinertson has worked with press technology for over 30 years. He can be reached by phone or fax at 616.467.8025 or via e-mail at Rreino@aol.com.