Dan Margulis Applied Color Theory

Duotones Using Metallic Inks

Subj: [colortheory] Duo Tones
Date: Friday, October 31, 2003 3:53:57 AM
From: Marco Blanco

Ok...  First off allow me apologize if you guys have recently covered this.  Recently I sent a file to Daily Variety to print a duotone PMS873 and Black.  I got a proof back, looked great.  Printed in DV and looked awfully dark.  What went wrong?  It couldn't have gained that much, could it?  One friend said I should have used a greyscale w/ a spot channel instead because since the black prints last the black printed over the gold, even though the black was set at 40 percent (?).  Another said I should have gone through Quark.  My question is, what is the proper way to prep a Duotone file for publication printing.

Thanks in advance,
Marco Blanco
Los Angeles, CA
___________________________________________________________________________

Re: Duo Tones
Date: Friday, October 31, 2003 7:01:40 AM
From: Stephen Marsh

Marco, unless a press proof, or a very well done analog proof - I would be doubtful of duotone proofing - even more so involving metallic inks that interact with the first ink as in a duotone as opposed to spot use of the metallic. I try to consult with the printer as much as possible for ink trap and ink sequence and other variables and to make it clear that this process can be great when things go right...but when things are bad, they are often a lot worse than more common four colour issues which most people are more used to handling.

It's a shame that Dan is away - I would like to hear his thoughts on the issue. We do have many printers and experienced prepress folk here, so with luck those with more knowledge on metallic work will post...I know enough to be wary, but never comfortable with 'remote' printing of these types of jobs.
 
Printed in DV and looked awfully dark.  What went wrong?  It
couldn't have gained that much, could it?

Can you post a low res thumb zip compressed still in the duotone format of the image to a site where the list can have a look at it, or offlist via email to me?

I suspect image content and or other page or press sheet content affecting things - is this web or flatsheet printing?

One friend said I
should have used a greyscale w/ a spot channel instead
because since the black prints last the black printed over the
gold, even though the black was set at 40percent (?).  Another
said I should have gone through Quark.  My question is, what is
the proper way to prep a Duotone file for publication printing.

It could be related to file construction, but it is probably a mixture of both file/image and press variables which have brought you to grief - probably the files density and the presswork over your choice of format for delivery.

I have had my share of success and failure with black/gold metallic duotones - success when the printer actually prints the ink sequence that you were expecting, failure when they reverse the ink sequence. The success story could have been even better, but I was being conservative with the gold ink density - if the printer had incorrectly reversed the ink sequence on this image, it would have been a lot better than the failure, but I upped the ink after seeing the first print (not expecting them to reverse order on the next job in the series) - but that's the way of things.

Communication with the printer is even more important than usual when doing jobs like this, and even then without a press check you can never be certain that your intent can be second guessed.

Stephen Marsh.
___________________________________________________________________________

   Date: Fri, 31 Oct 2003 07:18:10 -0500
   From: Laurentiu Todie
Subject: Re: Re: Duo Tones

The gold should be full in the midtone and low in the shadow, under black (almost knocked out by the black).
___________________________________________________________________________

   Date: Fri, 31 Oct 2003 06:37:02 -0600
   From: gary roushkolb
Subject: Re: Re: Duo Tones

Duotones will need to be created differently depending on what system the printer is using. We use a creo-scitex Bisque rip and I'll go through how we create duotones on our system.  First we start with a grey-scale, then make it a duotone in photoshop, now you can create the curves and gain to get the look you want and set the colors, photoshop even has some great presets.
    Now the rip-specific part, save your duotone as a psd file for back up and injet proofs. Next turn your file to multi-channel under "mode", and put the color to be overprinted as the last channel in the list. Save the file as a "DCS-2" in photoshop, You will have several versions, we use single file with a composite color preview for the creo system. You can place the file in Quark for output which is a low res image and you need to send a copy of the image to the rip that will replace the low res image on the fly. At the rip the colors have to be set to overprint each other.
    This is stuff your printer will take care of for you if you just give them a PSD or DCS-2 file and "talk" to them. Our duotones proof fairly accurately on an Iris proofer, but no duotone will be exactly like the printed piece. A general rule is make the duotone a little lighter than you want because of the gain on the press and paper, it's always easier the pump up the ink rather than take it away on the paper.
    I hope this helps,

Gary Roushkolb, Donlevy Lithograph - Wichita, Ks.  
___________________________________________________________________________

   Date: Fri, 31 Oct 2003 08:28:03 -0500
   From: "Preston Earle"
Subject: Re: Duo Tones

Stephen Marsh outlined some of the issues related to printing with metal inks. The main consideration is that because metallic inks are opaque, the order of the ink sequence is important. What's more, wet-ink-trap problems are more pronounced with metallics, particularly if the metallic is first down. (I wouldn't expect this to make an image darker, though it might make it more "golden". Pre-press proofs are not going to show these problems. I don't believe anything about the "metallic" ink would make the file print darker; perhaps the problem lies somewhere else. As a wild guess: did the job actually print in metallic gold or a process-build?

Preston Earle
___________________________________________________________________________

   Date: Fri, 31 Oct 2003 13:10:59 -0800
   From: Jono Moore
Subject: Re: Re: Duo Tones

Hi Gary, just curious as to why you use DCS for duotones. Standard Photoshop eps files work great and won't break composite workflows.

I don't understand the need to set overprints for a duotone either, unless it's something to do with having it as a DCS file or something in the workflow.

Or maybe I'm just dim. ;)
  --
Jono Moore
udoprinting.com
___________________________________________________________________________

   Date: Sat, 01 Nov 2003 02:41:46 -0000
   From: Marco Blanco
Subject: Re: Duo Tones

Thank you to all who responded, any other views would be greatly welcomed.  Sounds like I should have called the printer directly.  It's just that when I got the proof back it looked good so I thought...  In response to Mr.Gary Roushkolb, I did it in greyscale, converted to duotone using black and PMS 873.  The curves that were set up were: Gold 0 at 25 percent and the black 100 at 40.6 percent.  That's all.  We liked it better at the black 100 at 50 percent but dropped it down to 40.6 to allow for gain.  They were saved as PSD files.

Marco Blanco
Shoolery Design, Inc.
Los Angeles, CA
___________________________________________________________________________

   Date: Sat, 01 Nov 2003 19:56:51 -0600
   From: gary roushkolb
Subject: Re: Re: Duo Tones

On 10/31/03 3:10 PM, Jono Moore wrote:

I don't understand the need to set overprints for a duotone either, unless
it's something to do with having it as a DCS file or something in the
workflow.

The Creo workflow needs DCS files to see the spot colors.  When we were not using the Brisque we could use eps files  
___________________________________________________________________________

   Date: Wed, 5 Nov 2003 09:55:29 -0800
   From: "John McKercher"
Subject: Duotones inks and curves

I have some B&W images that we intend to print as duotones to accompany a book of poetry. The images are nudes featuring high contrast taken outdoors against backdrops of trees, rocks and shrubs. Some of the skin tone highlights are almost blown away to nothing and the effect the photographer was going for was a sort of dream-like image.

I've run some press tests using just the standard duotones curves in Photoshop and we got the best result using a Pantone cool gray 7 and black. Although we like the extra detail we are getting in the highlights due to the gray the one comment we had was that the blacks in the shadow were still not really dark enough. I also tried them with a warm gray 11 and a Pantone 144. For some reason when using the 144 the dot pattern was really obvious in the highlight areas of the image. Could this be from having the screen angle for the 144 set to the same angle as the black?

We are printing on a coated matte stock from positives. Everything was scanned at 350 and it was printed at 175 lpi. I've asked if we can specify stochastic screening to help reduce the dot pattern we are seeing in the 144+black setup highlights. I've read that when dealing with skin tones using stochastic can help in the printing. Would I gain anything by running at a higher line screen with a duotone?

I'm wondering if anyone has experience in printing these types of images as duotones and if they might have an idea of other ink combinations that would work and curves other than the standard ones loaded in Photoshop. It was suggested that instead of a gray+black combination running a double black would help but I'm not sure exactly why this would work any better or what the curve would look like. I've also read about using a black and silver ink combination but I don't have any experience with a silver ink. Any thoughts?

John McKercher
production/typesetter
Hartley & Marks Publishers
T: 604-739-1885 ext 106
F: 604-738-1913
___________________________________________________________________________

   Date: Wed, 5 Nov 2003 15:32:44 EST
   From: Dan Margulis
Subject: Re: Duotones inks and curves

John McKercher writes,

I've run some press tests using just the standard duotones curves in
Photoshop and we got the best result using a Pantone cool gray 7 and black.
Although we like the extra detail we are getting in the highlights due to
the gray the one comment we had was that the blacks in the shadow were still
not really dark enough. I also tried them with a warm gray 11 and a Pantone
144. For some reason when using the 144 the dot pattern was really obvious
in the highlight areas of the image. Could this be from having the screen
angle for the 144 set to the same angle as the black?

Yes. The additional ink needs to be set to either the magenta or cyan angle.

We are printing on a coated matte stock from positives. Everything was
scanned at 350 and it was printed at 175 lpi. I've asked if we can specify
stochastic screening to help reduce the dot pattern we are seeing in the
144+black setup highlights. I've read that when dealing with skin tones
using stochastic can help in the printing. Would I gain anything by running
at a higher line screen with a duotone?

Not unless you have a great deal of confidence in the capabilities of the printer. A large number of things can go wrong with such a fine screen, and still more with stochastic.

I'm wondering if anyone has experience in printing these types of images as
duotones and if they might have an idea of other ink combinations that would
work and curves other than the standard ones loaded in Photoshop. It was
suggested that instead of a gray+black combination running a double black
would help but I'm not sure exactly why this would work any better or what
the curve would look like. I've also read about using a black and silver ink
combination but I don't have any experience with a silver ink. Any thoughts?

Metallic inks are tricky to work with because of overprinting and dot gain issues. If you haven't tried it before, don't start now.

Duotoning with a gray + black, or a black + black, is fairly common. You shouldn't have any difficulty with the darkness of the shadow. You might try testing by printing a standard B/W next to the duotone. The duotone's shadow should be substantially darker. If it isn't, you need to adjust the shadow ends of the duotone curves, which is easily accomplished in the Duotone dialog box.

Dan Margulis
___________________________________________________________________________

   Date: Wed, 05 Nov 2003 12:57:09 -0800
   From: "Mac Townsend"
Subject: Re: Duotones inks and curves

the standard duotone curves are simply 45 degree curves. if you want more depth in the shadows, adjust the curves accordingly. The K and color plates are not usually adjusted the same, i tend to pull color out of the lower end and black out of the high end...because, probably, that's the way I used to shoot the halftones "in the old days"

silver ink is a problem because at a certain point the silver pigments (actually tiny metallic flecks) no longer ahdere to teh binders in the ink. Metallic inks ought to be run solid.

Mac Townsend
Adcom Graphics, Digital Imaging
Fairfield, California
www.adcomgraphics.com
___________________________________________________________________________

   Date: Wed, 5 Nov 2003 17:44:21 -0500
   From: "Preston Earle"
Subject: Re: Duotones inks and curves

You can choose a variety of combinations for the two colors. With black as the primary colors, the darker color you choose for the second color, the darker shadow you can achieve, but the greater problem you will face in holding shadow detail and keeping the shadows from being solid black. If you choose black/black duotones, you might start the second black with highlights starting at the mid-point on the density range (where the first black is 40-50%) and the shadows maxing out at about 50%. For lighter second colors, you can make the highlight lighter and the shadow point darker. You can imagine that if a 90% black overprints a 90% black, there isn't too much "paper" left to provide any shadow detail. However, if a 50% black overprints an 80% black, there are both double-black areas for additional shadow density and no-black areas to carry some detail.

Preston Earle

Adobe Photoshop training classes are taught in the US by Sterling Ledet & Associates, Inc.