Cannot figure out how to turn overprint on/off

[qtluong]

I retrieved a map with a relief layer that is overprinted. However, I cannot figure out how the person who created it made that relief layer overprint. If I select the relief object, I see that "Overprint Fill" is not checked in the "Attributes" panel, and does not seem to have any effect. My question is how do I locate the switch that turns overprint on/off for that object? In case looking at the file would be useful, it is here: http://terragalleria.com/private/CACAmap1_revised.ai

Conversely, I added a relief layer to another map, and when check the "Overprint Fill" box, no overprinting happens (overprint preview is on):

The file is here: http://terragalleria.com/private/VOYAmap1_revised.ai

Thanks

[mikehamm]

The Illustrator file your link points to is not accessible from the domain you provided.

Forbidden

You don't have permission to access /private/ on this server.

---

Apache/2.2.15 (CentOS) Server at terragalleria.com Port 443

[qtluong]

Sorry, I fixed the permissions.

[Mike_Gondek]

Images get in the way of this, so links panel >> go to link, then hide he linked image(s).

Select all, turn off the overprint on the fill

Select any stroke, select similar, then turn off the stroke. You can then hide that, and proof ntohign is left that has a overptin attribute set.

[Kurt Gold]

The first link in your post does work for me.

The light green path is overprinting (both fill and stroke). Not quite sure what you are missing here.

The second link does not work, as already stated.

[qtluong]

Curious, maybe some caching, but I have renamed it and tested the link:

http://terragalleria.com/private/VOYAmap1_revised2.ai

[qtluong]

Regarding the first file, I am trying to find out how to turn the overprinting off, whereas for the second I am trying to turn it on.

[Kurt Gold]

Now, the second link does work.

In both cases: Just select the light green paths, go to the Attributes palette and turn on or off overprinting for the fill and/or the stroke.

[qtluong]

This works for the first file, but not the second one, what did I do wrong?

[Kurt Gold]

Unfortunately, I cannot tell you the reason as in the second document the .psd file is just linked. That means that I do not have it when I open the file.

You may want to provide another sample file with the raster image embedded.

[qtluong]

Sure, here is the file with raster image embedded:

http://terragalleria.com/private/VOYAmap1_revised3.ai

[qtluong]

More happenings that I don't understand:

1. if I save the raster as a RGB or CMYK, it overprints, whereas if I save it as a greyscale, it does not overprint (as in previous example)

2. The overprint (RGB or CMYK) appears with a red/magenta cast instead of being color-neutral

I am able to reproduce that behavior with a third map as well.

Here are the full production files:

http://terragalleria.com/private/VOYAmap1_revised_relief.ai

http://terragalleria.com/private/REDWmap1_revised_relief.ai

What is the explanation and how to fix to have a color-neutral overprint?

[Mike_Gondek · Accepted solution]

Overprint does not work when you have like inks between  2 items. So you fill of 5c 10y 8k will not overprint your embedded image made of black

I took the black tint on the selected fill as an exam ple, and you can see that overprints now.

How to use overprinting in Illustrator

I stopped using attributes overprints ever since the transparency multiply came out, as for me is quicker and more efficient.

I could not downlaod the links in your post #11.

[qtluong]

Thanks again, this solved the problem, and I would never have thought of this!

I mentioned in post #11 that map in greyscale did not overprint, and in both of my files the issue is identical to the one you identified, so I was able to fix it. Just out of curiosity, I am still wondering why a monochrome raster in RGB or CMYK overprinted to a green fill results in a red cast. The text of the links I provided was correct, but for some reason the browser embedded the wrong link. Here they are again, http://terragalleria.com/private/REDWmap1_revised_relief.ai

http://terragalleria.com/private/VOYAmap1_revised_relief.ai

Thank you also for the recommended alternative method, I will make sure to use that instead of overprint going forward!

[Mike_Gondek]

I had to simplify your file to make any progress on this, but believe this is the issue.

The square above has overprint, below I removed the overprint, and instead used multiply.

Your color is 6c 0m 10y 2k. I thoguh this might be an optical illusion.

The 2 circle gradients are 1exactly same colors, but one on top seems to have move blue gradient at bottom due to background, and how our brain processes the visual.

Looking in separation preview Illustrator is acting strange. There may be something strange about tints and overprint preview, that I do not know about. Sorry cannot figure this part out for you, hopefully multiple will do what you need.

[qtluong]

Thank you again for looking into this. So if I understand well, it possible that the overprint will print OK and it may just be an Illustrator preview issue, but in any case it is preferable to use multiply/transparency instead.

Interesting bit about perception, I illustrated a similar effect here:

» Quick Processing Tip: White Application Background - from QT Luong's Blog

[Mike_Gondek]

use window >> separations preview to preview your overprints if you have any questions. I would seriously though look into using the multiple blending mode instread of overprint, you have more finite control..