Quality CTP with Inkjet Platemaking

Discussion in 'Platemaking' started by discountprintingservice, Mar 6, 2016.

  1. discountprintingservice

    discountprintingservice Senior Member

    Joined:
    Mar 4, 2007
    Messages:
    141
    Location:
    Georgia
    OUR SHOP AND OUR NEEDS
    We are a high quality shop and run to a calibrated gray balance on press for producing coated and uncoated CMYK work for runs up to 250,000 impressions. We also run single and multi spot color custom jobs. To remain competitive in our market we must have a high quality plate for an economical cost.

    OUR DECISION
    I have been following inkjet platemaking since its beginning years ago with the JetPlate system. Our laser CTP system had several service issues over the last 2 years as it aged so we made the commitment to go fully inkjet CTP in December 2015 and decommissioned our laser platesetter. One major reason for our decision was largely due to very poor support experiences with Mitsubishi Imaging. We experienced unfavorable machine down times on several occasions, lasting from days to weeks. Support problems were so bad several local techs trained by Mitsubishi simply choose to stop servicing their units, leaving us with little options for servicing our unit.

    THE IMAGING UNIT/EPSON

    Anyway, we decided that it made much more sense to replace an off the shelf imaging unit for much less that the cost of some component parts of our laser based system. For our imaging we choose our existing Epson R2400 which has the same K3 ink set as the 4880/7880 series. It is a 13" wide printer and works well for 2 up portrait presses including the Ryobi 3302/3304. This printer sold for about $650 new, the current newer equivalent model is around $800. The larger 17" and 24" models are well suited for larger plate size and/or higher volumes.

    THE RIP/FRONT END
    For the rip I tested or demoed a number of different rips including AccuRip, T-Rip, Film Maker, Ghostscript, iProof Imageset/Screenprint and StudioRip. Most all of these rips were designed for inkjet film making but all are capable of making inkjet plates if setup correctly. I choose StudioRip for its superior rip processing speed and dot quality. It was the most robust rip of all the ones I tested and it is designed for making plates and film for a variety of imaging devices including inkjet plates and film on Epson printers. My second choice was FilmMaker 4.0 by Cadlink but I passed on this one simply because it was noticeably slower at rip processing on the same Windows 10 computer as the StudioRip and I could see bottle necking issues there. With that said, FilmMaker was several hundred dollars less at $499 for the desktop edition which we tested a number of jobs including a four color process job at 150 lpi with surprisingly good results after we got a good calibration curve. StudioRip, however, seemed to be the better rip for the additional expense due largely to its server configuration, and the many available pre-press and platemaking tools & feature built into it. Some features like trapping, imposition and stochastic screening are add-ons but we are happy with 175 lpi AM dots and we trap in our native applications using the Adobe trapping feature and it serves us well.

    THE PLATES
    So we ordered the private labeled brand polyester plates (made by TechNova) from an online dealer. From what I have found these plates are sold under at least two private label brands, maybe more. There are other brands of plates (both metal and polyester) available and some require post processing, UV exposure, baking or a combination of. Our choice of plates seem to be performing well now but it did take some time to get used to how to handle them. We had some issues with ink on the press not adhering to the image on the plate but those issues seems to have gone away. From what we can tell with our own experience and consulting with our plate dealer, these plates need to thoroughly dry before going to press and the dealer recommend pre-wetting them. We initially used a laminator type curing unit for post baking and the plates came out at around 190 degrees Fahrenheit surface temperature but was only at that temperature for a few seconds as it passed through the unit. If you only need a few thousand impressions you can skip the post bake but let the plate sit for at least 15 minutes to thoroughly dry after imaging to make sure the resins in the inkjet ink dry so it will be ink receptive on press. We have since started drying our plates in an oven at 110 degrees Celcius (230 Fahrenheit) for 2 minutes per the manufacturer's plate spec sheet and the plates are now preforming excellent on press.

    THE QUALITY
    We can easily print 150 lpi at 1440 dpi and 175 lpi at 2880 dpi with excellent quality that is in my professional opinion of 30 years experience being comparable to our previous laser imaged silver based plates when viewed by the naked eye. Friday we delivered a very nice short run job of only 1000 pieces, a 4/4 11x17 retail flyers to a customer who loved the quality that came from our new inkjet plates using the 150 lpi screening. These plates are allowing us to remain competitive with short run full color printing as we can wisely run jobs as short as 500 sheets on the offset press while keeping the smaller runs from bottle necking on our digital press. The key to good quality screens and dots has very much to do with the calibration curve and dot choice combined with the right setting for the Epson printer. We use a quality plate reading densitometer to make our calibrations for linear plates, press dot gains, and gray balance curves. We highly recommend using one and taking the time to make the curves and test prints if you want high quality results. Our rip and printer is configured to apply approximately 30% of the normal ink lay down and uses only 1 ink channel to image the plates. We currently are using the light cyan channel but have also made plates successfully with the magenta, light magenta and light light black channels.

    PROS AND CONS
    One huge benefit with inkjet vs. silver based plates is we have yet to see a drift in dot gains with the inkjet device versus what we have experienced with the silver based plates as processor chemistry became old. Another great advantage is the cost savings we are seeing in plate chemistry, plus they are under $3 per plate and we can use both sides of the plates. The whole system new is very low in total cost for a platemaking investment, which consists of the software Rip, the Epson printer and a post baking unit. The only two disadvantages I have found are trivial for our shop - (1) poly inkjet plates can't be saved and reused like metal plates and (2) inkjet plate production is a couple minutes longer per plate than our old system from start to finish. While I don't see this as a real disadvantage, it does take some care in the handling and using of the inkjet plates, particularly on press during mounting and startup.

    MORE OPTIONS
    There is another CTP system worth looking at that has emerged called 123ctp which really caught my attention. They claim it is capable of 190 lpi on metal plates. It uses a PS postive plate (what they use in Europe) vs. negative plates (used in the US) in which they image the postive (rather than a negative) image with UV blocking black ink directly on the plate surface (an idea I experimented with several years ago using positive plates and saw the potential but lacked the time and resources to develop) eliminating film positives and then expose to UV light, was ink off & then develop.

    CONCLUSION
    Now in our third month of using these inkjet plates daily, we are committed to continue growing our shop with this proven and cost effective quality plate technology.
     
  2. dynamicprinter

    dynamicprinter Member

    Joined:
    Dec 11, 2008
    Messages:
    15
    Location:
    Connecticut
    I was wondering how you are making out using the epson R2400 with plates. I am thinking of purchasing a P800 to use with JT metal plates without baking them or using a rip. My runs are all short (under 5000) and usually 1 color.
     
  3. discountprintingservice

    discountprintingservice Senior Member

    Joined:
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    Location:
    Georgia
    You must have a rip and the oven for these to work. The rip you choose must have the capability of controlling how much ink film is applied to the plate by the Epson. If you don't have a rip you can't control how much ink goes on the plate and it will not work (I tried it). I recommend StudioRip or Genie/Filmmaker rip. We could not get plates to work without baking them. The non image are would take ink and the image area would not. Baking them resolved that problem. See the other thread post from today, I uploaded images from 2 process color jobs I ran.
     
  4. dynamicprinter

    dynamicprinter Member

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    Location:
    Connecticut
    Thank you, I will look into both of those. You are using polyester plates or metal?
     
  5. discountprintingservice

    discountprintingservice Senior Member

    Joined:
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    Messages:
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    Location:
    Georgia
    We are actually using 3 different inkjet CTP plates:
    • GenieJet (made by Technova aka Polijet)
    • JT Direct metal (MarkAndy/Presstek)
    • MetiJet (Technova)

    This thread was about the GenieJet, but the JT Direct works very similar to the GenieJet with double the rated run length. The last one is different in that you inkjet the image on the plate which is photosensitive with a special gelatin coating on the top layer of the plate to make it inkjet ink receptive. It is positive acting which is the opposite of the widely used negative acting plates used in the U.S. as it requires a positive image mask as opposed to a negative image mask, hence the name positive acting. The inkjet ink blocks UV light from the emulsion, after UV exposure you wash the inkjet ink and gelatin coating off the plate with water then develop the plate. It runs like a traditional metal plate with run lengths of 100,000 or more. The only real downside to it is it uses more ink volume in the inkjet to produce a dense image to block UV and it takes a little longer to produce the plate do due dissolving the gelatin coating but the time difference is minor by only a few minutes but that adds up if you have a lot of plates to make in a busy shop without a dedicated prepress person to make the plates. The trade off is a very high quality yet low cost plate that when imaged at 2880 dpi using 150 or 175 lpi rivals the quality of a laser based CTP system even when viewed with a loupe. So the savings of a new laser based CTP over a new rip, inkjet printer & UV light source is substantial potentially saving 10's of thousands of dollars or more for comparable quality. To boost production a plate processor with 3 tanks capable of dissolving the gelatin coating, developing the plate, and finishing the plate would be ideal to increase plate productivity to something comparable to a silver based roll feed laser system.
     
  6. dynamicprinter

    dynamicprinter Member

    Joined:
    Dec 11, 2008
    Messages:
    15
    Location:
    Connecticut
    I am a small shop and digital is most of my work today. I only do 5-10 plates a week when busy and tried laser polyester but had too many issues. I tested the JT plate which ran good but they baked them and MarkAndy/Presstek wants around 6k for the set up without oven so I figured I would try buying a P600 to print the plates since I only need 13" for an AB Dick 9800 series. Most of what I print on press is line/type with no screens and under 5000 impressions. They say you don't need to bake them under 5000.
     

  7. dynamicprinter

    dynamicprinter Member

    Joined:
    Dec 11, 2008
    Messages:
    15
    Location:
    Connecticut
    Well I bought an epson P600 and printed on the metal JT plates, I processed them as if coated paper. I baked 1 and the other sat a couple days, they both ran well except for the screens. Type and lines were okay but the screens filled in which I was expecting by your posts but gave it a try anyway. Am looking at a couple of the rips you suggested just looking to see what fits my low volume in 1 and 2 color printing on an AB Dick 9810. Thank you for your help I really appreciate it.
     
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