Printer Information
Description
Diamond Screening is the Linotype-Hell® implementation of stochastic screening. In conventional screening, dots vary in size to make areas darker or lighter and are spaced equally (150 lines per inch). In stochastic screening, dots are all the same size and move closer together or farther apart to make areas darker or lighter. In Tandem Design, Inc. endorses and encourages the use of Diamond Screening for all process color work, and other monochromatic or spot color projects as well.
How to Run It
If you currently produce plates and print 175 lpi screens or higher, you should not have to do much different to run stochastic screening. Diamond Screening negatives from In Tandem Design, Inc. are calibrated to print the same as conventional screening, with more latitude for ink density on press (you can run the ink heavier).
Pre-Press
We recommend that you take care to avoid procedures that cause you to have multiple thicknesses of tape or Þlm or carrier substrate in preparing the Þnished flats. Because of the relatively small spot size in stochastic screening, there must be very good contact between the emulsion side of the Þlm and the plate material when imaging plates. If an extra layer of tape is near a stochastically screened image area, the Þlm will be held away from the plate. This will alter the spot size transferred to the plate. Stochastic screening is less forgiving than conventional.
Projects controlled by In Tandem Design, Inc. will be full page negatives with all elements on the page. However, we do not control the design and pre-press of all jobs for which we image film. Therefore, if there are elements of a job that are to be stripped in, we recommend that you use separate carrier sheets, and double-burn the plates. This will allow the best transfer of the stochastic dot from the full-page negatives.
We recommend that you use 25-50% longer draw down times at plate making for stochastic screening. This will assure good contact between the emulsion of the film and the plate material, thereby optimizing spot transfer to the plate. If you already use longer draw down times for higher line screens, apply that method to stochastic screening.
Negatives from In Tandem Design, Inc., whether they be stochastic or conventional, are calibrated for normal plate exposure. We recommend that you use normal exposures at platemaking. With negative film, reduced plate exposure prevents transfer of the small spots. In some shops, positive film is used. A reduced exposure time improves transfer of the small stochastic spots. If you are using positive film, please, call us to discuss the production considerations.
Do not duplicate!!! If you need multiple copies of a negative, please, ask us to run them. If you try contact duplication of stochastic films, you will have unpredictable results. If your duplicating film does not have the identical dot edge characteristics of our original film, calibration will be out of control.
If you have a step and repeat machine, it can step stochastically screened negatives if its vacuum system is modern and capable of good plate making with high line screens (200 lpi or better).
Proofing
We recommend that you use Iris® digital proofs from In Tandem Design, Inc. for color decisions. When you use our scans, our digital proofs, and our negatives, you are dealing with a relatively well calibrated system. If you get film proofs from our negatives, you may not be able to get a close match on press. Film proofing systems are not necessarily reliable for stochastic screening. There is about 25% dot gain on press with our Diamond Screening (the difference in transmission densitometer readings for conventional screening and Diamond Screening on negatives that will print the same). This has proven to be true with Diamond Screening from other pre-press shops and with other types of stochastic screening. Some proofing systems allow for accurate representation of that dot gain. Other proofing systems allow for accurate transference of the small stochastic dot (which does not necessarily show the dot gain). If you have not printed a test and then calibrated the film proofing system, your best starting point is our Iris® digital proof.
We recognize that there are reasons other than color control to do film proofs, to include: checking traps, finding technical flaws in the negatives, checking the stripping and pagination, etc. We certainly recommend blue lines after stripping, and may encourage color film proofs at that stage as well, as a technical check on the job before printing. However, we strongly recommend that you use our Iris® digital proof to make color decisions on press.
On Press
We recommend that you reach normal densities across the sheet, before trying to get color of individual images. Your densities may be different, but on gloss-coated offset a starting point might be C-140, Y-105, M-150, K-170. Then, to get color, add ink (you should rarely have to take it away if you have started at densities you would normally use for conventional screening on the stock you are printing). Stochastic screening may allow you to take densities well beyond what you are used to. Blacks well above 200 and magenta and cyan near 200 (gloss-coated offset, sheetfed) are possible with many images without losing shadow detail nor dirtying up the highlights.
We recommend that you investigate the use of higher tack inks for optimal results. If you plan to do only a few jobs with stochastic screening, use your regular ink sets. If you plan to do a large amount of stochastic screen printing, consider some experimentation with your ink manufacturer (the reason for this consideration is wet trapping of the very small dots).
More to Come
Process color stochastic screening is here now. On the horizon is wide spread use of 5, 6, and 7 color process printing (referred to as "HiFi" color). Because there are no screen angles with stochastic screening, there is no potential for moire. Therefore, any number of inks can be used. Using bump colors to the standard process colors or using RGB components with a CYMK separation can vastly increase the color gamut, or the vibrance and impact of an image. Feel free to ask about this, if you have clients who might want to experiment with it.
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Diamond Screening® Presentation to VuePoint 95 and Conceppts 95 (an Acrobat® *.pdf document)
Diamond Screening Survey of Linotype-Hell® Users (an Acrobat® *.pdf document)
Diamond Screening Print Test Report to the Linotype-Hell Users Group (an Acrobat® *.pdf document)
Adobe® Acrobat® Distiller creates files in the Portable Document Format which can be read by Acrobat® Reader programs available for many different platforms, including MS-DOS®, MAC and UNIX. You may download the reader file for your platform from Adobe®. However, be advised that the files are over 1 Meg and may take an extremely long time to download, depending on the speed of your communications software and hardware.
Forward comments or questions to harry@email.intandem.com
Trademarks and Copyright
Some or all of the following trademarks are referenced in this and/or other documents associated with the In Tandem Design, Inc. World Wide Web site.
PostScript®,Acrobat®, PageMaker®, and Adobe® are registered trademarks of Adobe® Systems, Inc..
Diamond Screening®, Linotype®, Hell®, and Linotype-Hell® are registered trademarks of Linotype-Hell AG and/or eidelberg AG and/or its subsidiaries.
All other trademarks and registered trademarks are the property of their respective owners.
