Drop Shadows and Spot Colours oh my.

[Sherbert]

Hey you lot,

Been working with a file this morning. Basically a logo was missing when RIP'd.

Problem lied with the fact there was a 1bit tif printed with a Spot in the background. The logo had a drop shadow. So the logo was knocking out the background but the logo wasn't printed, only a white space.

Converted the Spot to CMYK and all is fine.

But, I am wondering with you people who would maybe run this with Spot inks. What would you do in this situation? Is there a better workaround to just coverting spots to process.

Edit: Indesign CS3

Regards,

Sherbs

[Lukas Engqvist]

Depends. If the customer is getting a CMYK job I'd have it in a hotfolder warning for Spot. (And then convert to CMYK if I found any Spot colours) If it was to be printed as a spot, well you logo will probably turn up on the spot plate.
We allways try to run PDF files through a visual if we get a preflight alarm, the separations pannel is so helpful

It isn't a bad idea to use the output pannels in InDesign either separations, inklimit, black text and strokes in black only and transparency flattener preview are good tools if used... well they're good tools even if you don't use them, but hard to benifit from what's not used.

[hansman]

what rip are you using?
Was the image set to overprint?
I haven't seen any spot issues in a while.

[Sherbert]

Standard one on the Indigo 5000. Harlequin variant.

Overprint an image? (Darken or Multiply?)

[Lukas Engqvist]

Transparency in Postscript is often used in Overprint, multiply is not supported in PostScript as far as I know. This is where the white may appear, there is some code saying that a logo will overprint in the Pantone, but renaming or remapping the Spotcolour will mess up the overprint logic especially if you have a "force knockout on white objects" fixup.

[graphicsource]

Did you ever get the answer you needed? From my experience, the issue is the shadow interacting with the spot color. It is a RIP limitation. The shadow is a "transparent" object, and the RIP can't handle transparency in conjunction with a spot color. We have an iGen3 and an Indigo 5500, and they both have that limitation. We also use Prinergy for offset, but it does not have that limitation. For digital workflow, we HAVE to change the spot color to process when it interacts with a shadow or effect that involves transparency, otherwise, the shadow knocksout the spot beneath or puts weird white lines at the bounding boxes.

[Glenn McDowall]

Quite often transparent TIF coloured as a spot will be flattened by InDesign into the PDF as Overprinting White. If its changed to cmyk the overprint no longer works on underlying cmyk, it needs a RIP to be set to simulate the overprints. If you go back to InDesign and change the spot colour to process in the Ink Manager it doesn't get the choice to use the Overprinting White. I'm sure that if this job was printed using the spot plate (as a 5th Ink) it would have worked correctly.

[Sherbert]

Hey all, sorry for the thread necro!

Had this again today.

I have a spot colour and on top of that is some text with a drop shadow.

Now when I convert this to CMYK via the RIP or using Ink Manager in Acrobat Pro the Drop Shadow drops off.

Any real reason why this is removed in the conversion?

[Lukas Engqvist]

You must first flatten transparency, simulating overprint, then you can use the inkManager.
Really transparency and spot colours is one stack of termites. Best is to tell the customer to remeke the PDF with no Spot Colours.

There are only a few RIP's that can handle converting from spot to CMYK and maintain overprint appearance.

[Sherbert]

Thanks for your reply Lukas, most helpful.

I didn't have much luck with this PDF when flattening inside of Acrobat pro then converting either.

As you said I think the best course of action is to get a CMYK only file!