Overprinting and spot colors - impossible?

[thadeusz]

SInce I switched to Publisher for all my CMYK work, I thought it might be time to do the same with a project using two spot colors. But I can't find a useful way to work with it. 
When using overprint properties Indesign makes it possible to do that per object (line or fill). I think it would be ok, to do it upside down, like the user guide of Publisher is promoting. That would mean to make a copy of a color swatch (one overprintig, one knocking out) and to use these on all objects as one wishes. And it does even work when outputing a PDF. But there is one thing missing - a preview of how my layout actually looks when overprinting, simple WYSIWYG (I'm not even speaking about a separation preview). So that is not very useful.

With CMYK colors it's quite easy - you can just use layer modes (multiply) - see, what you are doing and even get it exported in a controlled way, when using the right PDF export settings. But with spot colors I didn't get any of these exported, they always change to CMYK. I've tried all possible ways (my document is CMYK, FOGRA39 and exporting as X4, X3 or other variants didn't help; of course honour spot colors is on). Any ideas? Has anybody a real workflow for that?

Thanks for any help!!

[thomaso]

On 7/9/2020 at 6:35 PM, thadeusz said:

But with spot colors I didn't get any of these exported, they always change to CMYK. I've tried all possible ways (my document is CMYK, FOGRA39 and exporting as X4, X3 or other variants didn't help; of course honour spot colors is on). Any ideas? Has anybody a real workflow for that?

Actually spot overprint do export fine, in various PDF settings (v1.7 with or without profile embedded, or X-4).
Are you sure you created spot colors + overprint? Its swatch shows 3 markers (left, right, top right):

  If you select a global swatch it will tell its properties in the colours panel:

Here is a PDF you can check:    v183 spot overprint 1.7 no-embed.pdf

[thadeusz]

Thanks for looking into that!  - But what you show is exactly showing my problem. Maybe I was a bit unclear. In Affinity there is no preview of the result possible. What you see - when designing - is not how it will look at the end (when overprinting - here shown in Acrobat). Exporting spot colors in this case works for me as well. But how could you design without this preview? Imagine even several spot-colored photos on top of each other - hiding one another with their white backgound. Is there a way to preview overprinting live in Affinity?

Because of that problem, I've tried to use layer blend modes (multiply), as I do working in CMYK color space. But this results in converted colors (spot colors show always as CMYK). I couldn't find a way to prevent that.

[thomaso]

18 minutes ago, thadeusz said:

I've tried to use layer blend modes (multiply), as I do working in CMYK color space. But this results in converted colors (spot colors show always as CMYK). I couldn't find a way to prevent that.

Ah, I see. Sorry, first I thought you were not able at all to export spot colors as overprinting spot colors.

When using blend modes with spot colors you force Affinity to create colors which are NEITHER the spot colors NOR can't be created of them. Then it becomes relevant whether the blend mode is supported by the PDF format. Not every blend mode is supported in a PDF, this limitation is not related to Affinity but to the technical PDF specification *. Multiply is one of the few supported blend modes in PDF. Whereas for blend modes also the PDF setting gets relevant, too, in particular the PDF version and the Affinity settings in the "More" section: respectively the "Rasterize" and the "Allow Advanced Feature" options.  *  https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/PDF32000_2008.pdf

The non-spot colors get more obvious if you choose another blend mode, e.g. color burn or screen, which create colors which definitely aren't the spot colors. To create, show and output those the app MUST use the entire color space CMYK or RGB – or could alternatively refuse with an error message "you can't assign a blend mode to spot colors" – or, as it does, result in a different, unexpected appearance.

Note in this clip the differing appearance of both various blend modes AND various PDF settings in Affinity "More" options: The 1st/left PDF shows "Rasterize: Unsupported" while the 2nd/right shows "Rasterize: Nothing". The top left group has 'multiply' assigned.

v183 spot overprint 1.7 blend modes.pdf

v183 spot overprint 1.7 blend modes_no-rast.pdf

So, you should be able to export spot colors correctly even if set to blend mode 'multiply' – and use it this way as kind of a preview in Affinity as you do for CMYK objects. So if it still resists not to work for you may show your "More" setting screenshots and upload the according PDF, ideally with an Affinity document, too.

[thadeusz]

Thanks. I’ll have a closer look at those files when I’m back on Monday. But it looks good.

My question would be if this is also working with images (let’s say grey scale TIFF)?

[sfriedberg]

Related to gradients between spot colors, it would be nice to have a duotone/tritone color separation (screening) capability.  I used to use a plugin for Corel PhotoPaint years ago for poster and postcard work, and it was pretty marvelous to see full-color images separated out as spot color plates.

[thadeusz]

Thanks @tomaso for the hint! PDF 1.7 seems to work. I have to check back with the print shop, if they have problems with it. But in my case it looks like a good way to work.
Your explanation, that multiply is allowed in PDF, was also very helpful. Maybe that is a reason, why I have to use multiply directly for images, not for images boxes. But then again it works for groups correctly. Very weired.
Working with spot colors should be more reliable and documented. I know, that most jobs nowadays go online and only have CMYK colors. But it's still an important way to print in many cases.

[thomaso]

26 minutes ago, thadeusz said:

I have to use multiply directly for images, not for images boxes.

Hm? What appears differently if you apply the blend mode to the picture frame, not to its child image inside?

[thadeusz]

At least when I've tried it, it didn't overprint, but seperated to CMYK again.

[thomaso]

3 hours ago, thadeusz said:

it didn't overprint,

Oh, sorry, I forgot the initial issue. – And, sorry again: Of cause it causes a different appearance whether the color gets applied to the frame or to the image. If it's applied to the frame then the frames background does overprint but may be covered by the image (which remains opaque). So to overprint a (not-spot-colored) image, too, you would need the multiply blend mode for the image, which, of cause, forces a different appearance on the colored frame fill. – By the way: When assigning a color to an image make use of the "K Only" button.

Here no multiply is used, only the overprinting spot color + K Only button.  v183 fill color overprint frm vs img 1.7.pdf

 

[GoPrint]

On 7/11/2020 at 3:27 AM, thomaso said:

Actually spot overprint do export fine, in various PDF settings (v1.7 with or without profile embedded, or X-4).
Are you sure you created spot colors + overprint? Its swatch shows 3 markers (left, right, top right):

  If you select a global swatch it will tell its properties in the colours panel:

Here is a PDF you can check:    v183 spot overprint 1.7 no-embed.pdf

 

Hallo Thomaso, thank you so much for your helpful answers. I see that you use German. I live in Austria doing publishing work with some german printing companies. I have been struggling with Affinity spot and overprint since my partner has instruction only for Adobe products, not for Affinity. May I request you to kindly help me with the following "Anleitung" if you have time to achieve correctly in Affinity Designer or Publisher (English)? Here is the Anleitung text:
"Bitte den partiellen UV-Lack als Volltonfarbe (100% Magenta) anlegen und als Lack bezeichnen. Alle Flächen mit der Farbe Lack müssen auf Überdrucken stehen, voll deckend sein (kein Raster!)"

The 2nd sentence with "Alle Flächen mit der Farbe Lack..." is what I don't understand and cannot do that i Affinity.
I will highly appreciate if you can help.
Thank you.
Aboi

[thomaso]

31 minutes ago, GoPrint said:

"Bitte den partiellen UV-Lack als Volltonfarbe (100% Magenta) anlegen und als Lack bezeichnen. Alle Flächen mit der Farbe Lack müssen auf Überdrucken stehen, voll deckend sein (kein Raster!)"

The 2nd sentence with "Alle Flächen mit der Farbe Lack..." is what I don't understand and cannot do that i Affinity.

The meaning of the instruction in this part is independent from an application and doesn't differ between Adobe and Affinity.

The second sentence means accordingly that …

• overprint/Überdrucken has to be activated for the spot colour,
• layout objects have to get it assigned in 100% (no reduced tint/Ton),

And to prevent from rasterization:

• no effect/filter/adjustment must be applied to these layout objects,
• no image/pixel layer may get it applied,
• the according objects must have their layer blend mode = "Normal" + their layer opacity = 100%.

Below the swatch creation and use in steps 1-5:

[GoPrint]

I am extremely thankful for this valuable help and for taking time to explain in detail. You have saved me from a great trouble. Very clear and easy to understand. Thank you very much.

On 7/11/2020 at 3:27 AM, thomaso said:

Actually spot overprint do export fine, in various PDF settings (v1.7 with or without profile embedded, or X-4).
Are you sure you created spot colors + overprint? Its swatch shows 3 markers (left, right, top right):

  If you select a global swatch it will tell its properties in the colours panel:

Here is a PDF you can check:    v183 spot overprint 1.7 no-embed.pdf

 

 

[Klababa]

Hello, is there any option to add color with overprint to application pallete? 

[walt.farrell]

13 minutes ago, Klababa said:

Hello, is there any option to add color with overprint to application pallete? 

No, because a Spot Color must first be a Global Color, and Global Colors exist only in Document palettes, not in Application palettes.