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Color Theory Questions - Adobe Photoshop 7, CS, CS2 & CS3

John - most gravue printing uses opaque ink. You get gray levels from the line or cell density. Same as with black and white halftones - but gravure can hold lines, dots, odd curves, or whatever shape you want......

  1. #21

    Default Re: Color Theory Questions

    John - most gravue printing uses opaque ink. You get gray levels from the line or cell density. Same as with black and white halftones - but gravure can hold lines, dots, odd curves, or whatever shape you want...
    Chris_Cox@adobeforums.com Guest

  2. #22

    Default Re: Color Theory Questions

    ....hmmm, I had gotten the impression that all the cells were the same size on a given plate, but varied from plate to plate to avoid moire.
    John_Slate@adobeforums.com Guest

  3. #23

    Default Re: Color Theory Questions

    Hey, I could be wrong. Most of what I know about gravure comes from some anti-forgery folks... I've never actually played with it myself.
    Chris_Cox@adobeforums.com Guest

  4. #24

    Default Re: Color Theory Questions

    I looked it up <http://www.pneac.org/printprocesses/gravure/moreinfo13.cfm>

    And it appears that both are correct, depending on whether you are using chemical etching or electromechanical etching.

    Gravure sounds like a natural for digital processes. It feels strkingly similar to CD burning.

    Hey, the Cubs just won again, 3 games to 1.

    Go CUBBIES! :-):-)
    Lawrence_Hudetz@adobeforums.com Guest

  5. #25

    Default Re: Color Theory Questions

    I know nothing of printing -but: A sylus implies a cone, thus the volume of the well increases as a function of the angle the side that determine the "sharpness" of the point. This is a power curve (a second power). So an increase in depth would make the size of the hole at the surface a larger area. The dots are larger and fewer can fit on the surface in a given area. Thus an increase in applied voltage increases the ink volume (and not liearly) and the size of the applied ink. This is a very informative discussion. Thank you.
    Henry_Skinner@adobeforums.com Guest

  6. #26

    Default Re: Color Theory Questions

    The editorial color in National Geographic is done by rotogravure.
    John_Slate@adobeforums.com Guest

  7. #27

    Default Re: Color Theory Questions

    The stylus may not be a cone. I sure would like to know more about it.

    The record cutting stylus is not a cone, whereas the playback stylus until the last few years of vinyl was a cone. Elliptical stylus' were introduced so that the playback came closer to the cutter.

    I went back to the reference above and it states that the stylus is an inverted pyramid, not a cone. Still a second order function, however.
    Lawrence_Hudetz@adobeforums.com Guest

  8. #28

    Default Re: Color Theory Questions

    As a matter of fact, rotogravure is more popular than it seems at first. Any printing run that's big enough benefits from being printed in rotogravure in comparison to offset.

    I do not know the US market <http://www.gaa.org/home.htm> but in Europe, lots of magazines (German Burda and the like) are printed with rotogravure.

    Here you have the proccessa <http://www.wmich.edu/ppse/gravure/pp1.htm> reasonably well explained.

    Excuse me... but no one has answered yet Stephen question, I think (not that I know the answers, just trying to brint the thread back home. I am curious ;) )

    Gustavo Sánchez

    (POsted from Spain)
    Gustavo_Sanchez@adobeforums.com Guest

  9. #29

    Default Re: Color Theory Questions

    Hi all, back from vacation - and back to the grindstone ;)

    You can't vary ink film thickness with an electromechanically engraved cylinder - you could, traditionally, with etched cylinders -etch a specific area longer and you will get more ink volume.

    Gravure has traditionally been thought of as a process for long, consistant runs of high volume products - and still is - but many of us gravure printers are working to change that to short runs as well. Gravure offers superior color consistancy in long and short runs. We can also print beautiful metallics (true metallics, not silver with toners). The cost of the cylinders themselves has always been prohibitive for short volume business - the industry is constantly improving this price with newer/faster/better technology. Over the years, the company I work for has printed well known packaging, such as Marlboro, Crisco, Campbell Soup, and Wrigley gum wrappers (buy a box of Eclipse gum - the cardboard container is printed gravure - not by us though). The folded carton you get McDonald's French Fries in is gravure as well. Just about every package involved in the cigarette business is gravure - the soft pack, flip top box, carton - I think even the tipping on the actual cigarette is even gravure.

    For more information - check out www.gaa.org

    No, the diamond styli we use are not conical - they are shaped more like a poorly built pyramid - for lack of a better ogy.

    To give you an idea of the "hole" created on a standard spot color cylinder, here is how the "perfectly" engraved cell would look:

    Keep in mind that these cells are diamond shaped, with a thin wall of copper between them and an opening at each end called a channel.

    Our standard specs for line/spot colors are 175 lpi with a 45 degree compression. The wall of copper between each cell should be 7 microns wide. We also use a 120 degree stylus for this.

    The cell height would be 183 microns and the width would be 160 microns. The channel between cells would be 23 microns. This will give you a cell depth of 46 microns. All told - approximately 225,403 cubic microns per cell - these numbers are based on some funky DOS program that was written 15 years ago - I can't attest to the accuracy ;)
    Stephen_Klepper@adobeforums.com Guest

  10. #30

    Default Re: Color Theory Questions

    I suggest you ask this question on the Print Planet Forum. These guys are the color/printing experts. Just go to printplanet.com and pick the proper E-Community. They have forums for every aspect of printing and color management.
    Becky_Alex@adobeforums.com Guest

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