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Question HP 365 Users. What the deal with the number of passes?

Discussion in 'Digital Printing' started by Bradw99, Jul 22, 2019.

  1. Bradw99

    Bradw99 New Member

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    We are new to the latex 365 and I have some questions about which number of passes to use. I would like to hear from operators that are running the wide format.
    The default profiles give you normally 3 choices, 4pass, 6pass, 10pass. What does that mean? Does the 10pass put 2.5 times the amount of ink down on the material? Do you want to go to the lowest amount of passes and hold minimal quality?
    I need help understanding why?
    Thanks
    Brad
     
  2. bannertime

    bannertime "You guys do banners, right?"

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    We run 6/90 on banner and 8\100-12\120 pass on self adhesive vinyls. 16/120ish on backlit prints. We have a 4/90 pass setup for outdoor banner with one or two colors max.

    Basically it determines how many times it'll pass over a given area and lay down ink. The ink density or the second number you'll see determines how much ink. So a 4/90 will use less ink than a 10/90 and a 10/90 will use less than a 10/120. If it's 2.5 times as much, I don't think so. The second number is a "percentage." 90% density vs 120%.

    It determines speed and color accuracy. A high pass and high ink density will have much better color than a low pass low ink density, but also be much, much slower. You've got to determine where you want to be. I've seen people mention they run like 12 and 16p at 120% and up on ij35c and that's just pointless to me. It's promo material. If we're talking long term graphics then sure. We'll run 8/100 for cheap SAV for coro signs. I saw a premade banner profile the other day that was 10p something, and it made me cringe. Our 6p already looks way better than anything Vista, 4over, S365 sends out and people aren't bothered by that. Who's out there running 10p on 13oz vinyl? Anyway, to each their own. It's all up to you.
     
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  3. Christian @ 2CT Media

    Christian @ 2CT Media Major Contributor

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    Passes is not directly tied to ink usage but it can result in higher ink usage.

    Passes will affect Color quality, image quality, and gradient blending. But that's not to say that a lower pass count is not a sellable product to most clients. 4 Pass is typically unusable for most clients except for certain situations.

    Are you building your own presets and profiles?
     
  4. Bradw99

    Bradw99 New Member

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    Not yet, still getting my "sea legs" on this new machine.
    Brad
     
  5. ikarasu

    ikarasu Very Active Member

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    We generally 10p everything. Sometimes well 8p banners or cheaper material we know is staying up for a short time. F

    Why? Sure it's slower and sure it uses more ink... But ink is pennies on the job. Time wise if we're busy well drop the passes down, but if we're not well eat the minimal ink costs and up the passes and get better color/graphics. Usually while the printer is printing I'm laminating or flatbed ing or using the graphtec... So it going a bit slower doesn't bother us.

    I was going to ask about if you guys always did 600 dpi... I read no matter what you rip it as it prints at 600dpi (1200 if above 18pass) so I was curious why there's profiles for 150/300. I wanted to confirm I read That so I didn't sound like an idiot and found the following..


    https://supportvideos.ext.hp.com/de...odes-while-using-the-same-1200-dpi-resolution

    The hp tech says the printer always prints at 1200 dpi. Whether your on 4 or 10 pass... That 4 pass 100% ink should look the same as 10 pass 100% ink. It might be too much ink for it to dry properly at the speed.. But it's supposed to look the same.

    That goes against everything I thought I knew... But this is the main hp tech guy... Thoughts? I'm tempted to go try a 2 pass 100% ink and see what it looks like

    If that's true I'd just invest in some thermal ir heaters like they use for.vehicle wraps, throw it infront of the printer for some extra dry time.... Print at 2 pass all day.
     
  6. Christian @ 2CT Media

    Christian @ 2CT Media Major Contributor

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    2 pass is limited to 50% density... We print 100s of rolls a year of 2 pass wrap film.
     
  7. ikarasu

    ikarasu Very Active Member

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    Is it true that 6p/100 is the same quality as 10p/100? So long as it can dry fast enough though? I always thought higher pass was higher density.

    Hp tech guides say you need 18p to get to 1200 dpi. But this guy is saying you're always printing at 1200dpi... Seems like there's conflicting information. And this video was posted a month ago.
     
  8. equippaint

    equippaint Very Active Member

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    I think vanderj laid this all out pretty well but dont remember how it went.
    Pulling this out of my a*ss here, if passes put the same amount of ink down like the hp guy said then id think of it like spraying paint. Say you have a pint of paint and a 4x8 panel to spray. You can lay the pint down in 1 coat and possibly run it or get solvent pop, 2 coats with less risk or stretch it to 3 or 4 coats. Each way puts down 1 pint and the mil thickness is the same. 4 coats takes longer but the paint flashes faster with thin coats. 1 coat is fast but loads it on quick and may bury solvents and take longer to dry to handle.
    Is this totally off base?
     
  9. Christian @ 2CT Media

    Christian @ 2CT Media Major Contributor

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    Yes and No, our 6 pass profiles have been highly successful for us and 8 or 10 pass is only really needed for super vibrant rich colors. Our default is our 6 pass and now with our better profiling process it's even better... We can hit almost all of the popular PMS colors except for a few brighter Magenta heavy colors due to the HP Latex limited gamut in that realm.

    These are all 6 pass on the 570s
     

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  10. Reveal1

    Reveal1 Member

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    That's some awesome work there 2CT. 6 pass is also our goto for just about everything on our 560. For Canvas and other material with rough surface requiring more detail we use 12 pass and higher sometimes with translucents.

    Sometimes we'll see some horizontal banding in solids as printheads age that alignment won't fix - time for new ph or up passes short-term. (I consider the disposable heads an overall plus and factor their replacement into my pricing so out they usually go) I think Bannertime and equippaint together have the right concept; passes are the number of times the printheads pass over a given area. However, less ink per pass, more overlap, but roughly same or slightly more ink used for that given area. Because their is more overlap = less noticable banding.
     
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  11. Dukenukem117

    Dukenukem117 Member

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    According to what I've read from HP, 8 pass - 100% is the 'baseline' that everything is relative to. So if you go with less passes than that, in theory you are suppose to reduce the density. Vice versa, if you want to increase the density, you should increase the number of passes so that it has more time to dry in the curing chamber. If the material does not stand up to high heat very well, then decreasing the temp and increasing the number of passes may solve the issue. I'm paranoid about ink not drying and ruining a roll (and possibly gunking up the inside of the printer), so I rather run more passes to be safe on that, even if it means slowing output.

    I have no idea what the deal is with DPI and why you have so many options there.

    Modding your curing add-on is certainly an interesting idea. I probably would never try it myself but I'd love to see if it works.
     
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  12. jimmmi

    jimmmi Member

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    Has anyone tried to print for example 1m² image with 6p or 8p 100% ink density and the same image 18p 100% ink density? Ink ml spent are the same or for example the double?
     
  13. Bly

    Bly Very Active Member

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    We just use 10 pass for most stuff because that won't band unless you have a head on the way out.

    That's not very fast.
     
  14. jimmmi

    jimmmi Member

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    On 6 passes for pvc banner do you have banding?
     
    Last edited: Sep 24, 2019
  15. Dukenukem117

    Dukenukem117 Member

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    Ink density is what drives ink usage, not passes. More passes = better print quality and more time in the curing chamber. That's why you cant use crazy high ink densities without using very high passes.

    The only exception is possibly your first print after bootup. I've noticed that print tends to be higher for some reason, possibly because its doing some startup maintenance and lumping it together with the job accounting.

    I also got a reply from HP regarding DPI - the default printing DPI on all prints is 1200. RIPs like Onyx segment that into rendering resolutions.

    https://support.hp.com/us-en/document/c04390603
     
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  16. Kemraj

    Kemraj New Member

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    Good day what ink density you use for your 6 Pass.
     
  17. Christian @ 2CT Media

    Christian @ 2CT Media Major Contributor

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    80-100% depending on the material and what load it can handle at speed.
     
  18. greysquirrel

    greysquirrel Member

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    Brad, who did you buy this printer from? An authorized reseller should have a technician on staff that should have given you this information when they installed it or when you saw it in a demo. If they did not, I'd reach out to HP directly and let them know you received spotty training. They will probably send one of their guys out for you and flag the dealer. You can also go to hp's latex website for videos and other training. Everything 2CT says is correct...higher the passcode focus's ink in a smaller are when firing to help mask any possible imperfections in the passes. 18 pass is the only way to get a true 1200x1200 dpi profile...but it is super slow....maybe photo base paper or backlit film...I can not see any other place you would use it.
     
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