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Mesh gradients using pantone colors

Mar 18, 2013 8:45 PM

Hi,

 

I'm struggling to create gradients for screen printing purposes. The artwork will be printed on 12oz canvas using 3-4 pantone spot colors.

 

1) if I fill an object with a single Pantone color, create a mesh gradient from it using a variety of different opacity settings, say 100%, 50% and 25%, then play around with the mesh handles to produce a pleasant, mixed background, will a gradient of this type work for screen printing? I don't know if a gradient of this type will require halftones, as a linear or radial gradient would.

 

2) it's my understanding that when you prepare artwork for screen printing using spot colors, each color should be on its own layer. In an attempt to add highlights or shadows to an object, if I copy an object and paste it in front of itself, then apply a gradient using another Pantone spot color, say Pantone Process Black(100% to 0% opacity), does it matter what the blending mode is? Obviously you'll get different results based on the option you choose, but again, I'm concerned here only with screen printing. I can then place the gradient on the Black layer.

 

The problem is that I'm familiar with off-set printing, and apparently gradients have to be converted into halftones when screen printing, so I'm trying to figure out the best way of creating shadows and highlights.

 

Thanks for any help you can provide.

 

Mark

 

pantone.jpg

 
Replies
  • Currently Being Moderated
    Mar 18, 2013 11:25 PM   in reply to Fun Seeker

    1) A gradient is a gradient. They all require halftones for screen printing. Makes no difference if it's linear, radial, mesh or anything else. It's a continuous tone which can't be represented naturally and must be converted to a halftone to match a screen.

     

    2) Yes the blending mode matters. The appearance you see created by blending modes is due to a mix of the colors which wil occur when artwork is flattened. If you flatten two spot colors, you get a CMYK color. You would be better served by avoiding all blend modes and turning on Overprint Preview (View menu) and then setting objects to overprint via the Attributes panel.

     
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  • Currently Being Moderated
    Mar 19, 2013 2:29 AM   in reply to Fun Seeker

    I think you are overthinking this.... Textile printing is no different than offset printing in that regard, only that the resolution may be even lower with most direct printing methods like silkscreens or inkjet due to the absorption of the fibres causing more gain on the dots... If you want some gradients, but otherwise sharp elements, put them on different plates and/ or manually halftone your gradients by tagging them accordingly for the RIP or using lame ways like halftone filters. Beyond that most of that doesn't matter for any transfer-based methods like foil printing or even using a white underprint under inkjet. It really comes down to what method you actually plan on using.

     

    Mylenium

     
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  • Currently Being Moderated
    Mar 19, 2013 2:48 AM   in reply to Fun Seeker

    it's my understanding that when you prepare artwork for screen printing using spot colors, each color should be on its own layer.

    Where did you get this idea from? Layers have got nothing to do with colour separations.

    I have heard this sort of thing before but it’s a complete misconception.

     

    Use spot colours and overprints (with Overprint Preview). No need to bother about layers.

     
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  • Currently Being Moderated
    Mar 19, 2013 8:44 AM   in reply to Fun Seeker

    Mark,

     

    Getting your head around a few age-old fundamental repro principles will clarify this stuff for you:

     

    • First and foremost: Think in terms of INKS, not "colors." Take off your designer hat and think like a mechanic. You're dealing with real-world substances: scoops of thick, gooey, solid-color ink that will be squished onto some object.

     

    • Line Art: Artwork designed to be reproducable using only areas of solid ink coverage. No graduations of any kind whatsoever. In other words, nothing but 100% "tint" (often called "solid") of the ink(s).

     

    • Tint Screens: Uniform coverage of a given ink, but at any percentage other than 100%.

     

    • Continuous-Tone Artwork (often called "contone"): Anything involving varying percentages of a given ink, be it a "grayscale" gradauation of a single ink or graduation involving two or more inks.

     

    • Halftone: A photomechanical process used to distribute small dots (or lines, or some other pattern) of ink so as to SIMULATE tints and/or gradations. That's the important concept: There are no "graduated inks." Any given location on the final print either has ink or it has no ink on it. The ink is always a solid color. So anything other than the actual color of the solid (100%) ink is a mere SIMULATION.  That simulation requires that the ink be laid down as a series of tiny dots (or array of lines, etc.) so as to suggest things other than the 100% color of the actual, physical ink that is loaded into the press (or silkscreen).

     

    • Spot-color (opaque) versus process-color (translucent) is a SEPARATE ISSUE from line art (no tone screening) versus contone art (tone screening required). You are confusing those two separate and distinct issues.

     

    Now put this in the context of screen printing:

     

    • All artwork involving  tints or continuous tone requires halftoning. Compared to offset lithography, screen printing is very limited in its ability to handle halftoning. Many small local screen printing shops can't do halftoning at all. Typical medium-size screen printing shops (local T-shirt shops, etc.) can often do halftoning at a very course frequency (i.e.; large dots), often no smaller than 30~50 Lines Per Inch (LPI), and both color fidelity and sharpness suffer. Only larger and more sophisticated screen printing shops, running expensive, high-end automated equipment utilizing very fine screen mesh fabrics can reliably hold small halftone dots and consistently maintain color.

     

    Bottom line: The way you prepare artwork for screen printing is highly dependent upon the kind of shop that will be doing the printing.

     

    • Screen printing is done on a wide variety of materials (substrates). Substrates are quite often not white. They are often dark. So spot color inks designed for screen printing are usually very opaque. That puts them in a whole other world from the almost-always translucent inks of offset lithography, AND from the real world that Illustrator's interface is capable of simulating. Illustrator does not provide any means by which to specify the real-world opacity of a Spot Color Swatch. So when you use blends, grads, and overprinting, Illustrator cannot do a good job of simulating what you will actually see in the final screen printed results.

     

     

    Bottom Line: If you are building continuous-tone artwork involving blends, grads, tints, etc. (i.e.; anything requiring halftoning) and/or overprinting, you need some real-world experience to reasonably well anticipate how your halftoned artwork is going to look when printed. Best advice is to start simple. Design around your limitations, and those of the screen shop you will be using. Limit your designs to spot colors and entirely line art.

     

    Now to your specific questions:

    I'm struggling to create gradients for screen printing purposes.

     

    Grads are going to require halftoning. Have you asked your screen printer what halftone frequency (LPI) he is able to reliably hold?

     

    The artwork will be printed on 12oz canvas using 3-4 pantone spot colors.

     

    Understand: Pantone is a company. The Pantone company publishes its own standardized formulae for its own branded inks, which are offset lithography inks, not silkscreen inks. In other words, it's just a commonly-used color reference. You would be better off refering to actual color swatches of the actual screen printing inks your screen printer will be using. Set up your Spot Color Swatches in Illustrator corresponding to the actual inks.

     

    1) if I fill an object with a single Pantone color, create a mesh gradient from it...

     

    Always state WHAT VERSION of Illustrator you are using. Grad mesh did not always support spot colors. Blends still don't.

     

    ...using a variety of different opacity settings, say 100%, 50% and 25%...

    Don't confuse "opacity" with "tints." What Illustrator calls "opacity" and "transparency" usually involves rasterization and/or conversion to process color.

     

    ... then play around with the mesh handles to produce a pleasant, mixed background, will a gradient of this type work for screen printing?

     

    It will work for screen printing IF:

    • The particular screen printing setup adequately supports halftoning.
    • The mesh is built appropriately for the color separation model (spot, process, or process-plus-spot) that will be used to print it. Again, you have to be aware of the number of INKS that you are designing for, and make sure your design does not require more than that when it is color-separated (think "ink-separated").

     

     

    Current version Illustrator provides a color-separation preview feature, which can save you alot of grief if you use it. If using an earlier version, but have Acrobat Pro, save the file as a PDF, open it in Acrobat, and use its Separation Preview feature. If using an earlier version and do not have Acrobat Pro, "print" as color-separations to a PDF virtual printer like Adobe PDF. Then open the PDF in Reader and study the separate pages. (Screen print jobs are, in fact, often delivered as such a pre-separated PDF.) 

    I don't know if a gradient of this type will require halftones, as a linear or radial gradient would.

    Based on the above, you should now know that. Yes, ANYTHING that involves graduated color requires (at least a simulation of) "graduated ink". Since "graduated ink" does not exist, halftoning (or some other kind of tone screening--there are others) is required in order to simulate it.

     

    2) it's my understanding that when you prepare artwork for screen printing using spot colors, each color should be on its own layer.

    No. Absolute nonsense. (Don't believe everything you find written by self-proclaimed "experts" or "tutors" on the web, no matter how fancy you think their demonstrations are.) If that were true, then how, (for just one example) could you possibly screen print a rectangle with a spot-to-spot grad fill? The path containing that grad resides on one Layer, doesn't it?

     

    In an attempt to add highlights or shadows to an object, if I copy an object and paste it in front of itself, then apply a gradient using another Pantone spot color, say Pantone Process Black(100% to 0% opacity), does it matter what the blending mode is?

    Yes, it matters. Blending Modes has to do with so-called "transparency" effects. Again, anytime you muck around with "transparency" you increase the liklihood of rasterization and/or conversion to process at output. You would be safer setting that copied, pasted, grad-filled object to overprint. Halftoning will still be required, at least on the separation corresponding to the ink(s) for that grad.

     

    Obviously you'll get different results based on the option you choose... I'm concerned here only with screen printing.

    If you are designing for SPOT COLOR screen printing (as opposed to process color), stay away from transparency effects unless/until you understand what you're doing.

     

    I can then place the gradient on the Black layer.

    Again, forget Layers corresponding to ink separations. A total misconception. Utterly unnecessary.

     

    The problem is that I'm familiar with off-set printing, and apparently gradients have to be converted into halftones when screen printing, so I'm trying to figure out the best way of creating shadows and highlights.

    The best way to create shading is HIGHLY dependent upon the technical capabilities of the specific screen printing shop. Always ask:

     

    • Can the shop support halftoning?
    • If so, what is the maximum halftone ruling (LPI) they can reliably hold on the particular target substrate? (If they don't understand this question, either stick to line art or find another screen shop.)

     

    This does not mean that you cannot do shaded artwork without halftoning. (In fact, much of the most stunning screen-printed work is done entirely as line art.)  Designer fully acquainted with the limitations of screen printing commonly employ artwork shading techniques to avoid the need for halftoning altogether. They use hatching or stippling or contour linework to build "shading" into the artwork, and all inks are printed as line art. In this regard, preparing artwork for screen printing is often more "creatively rewarding" because you first, understand the real-world limitations of the reproduction method and, second, devise clever and original artwork methods to work within those limitations.

     

    But it's not something anyone can give you a step-by-step, one-size-fits-all-situations crash course in, in an online forum.

     

    JET

     

     

     

    JET

     
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  • Currently Being Moderated
    Mar 19, 2013 6:01 PM   in reply to Fun Seeker

    You can quote articles till you’re blue in the face but “Keep all your colours in separate layers, because every color will be printed separately.” is very bad advice.

    Separations have nothing to do with layers.

    Layers are just glorified groups of objects that can sometimes simplify your workflow.

    Read James’s comments carefully. He has some good stuff for you.

     
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  • Currently Being Moderated
    Mar 19, 2013 6:14 PM   in reply to JETalmage

    Good stuff James.

     

    In the old days when I learned screenprinting we sometimes used to mix the colours on the frame thereby alleviating the need for halftones.

    Things like skies, dark at the top, lighter at the bottom, were done by mixing a darker colour at the top of the frame and a lighter one at the bottom.

    Give the ink a bit of a stir in situ and drag the squeegee from side to side.

    If you are reasonably competant you can get lovely soft results with this method and no need for rough dot screens.

    My advice would be to avoid halftones as much as possible when working with silkscreen.

    Think of jobs in flat colours, unless of course you want to use dot screens as an effect.

     
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  • Currently Being Moderated
    Jul 1, 2013 1:04 AM   in reply to Fun Seeker

    Two additional replies have been removed from this thread. Insulting other forum users is not tolerated.

     
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