February 7, 2007

White overprint strikes again

While working at my father-in-law's print shop last year, I remember a file that gave us much trouble when we were trying to get it to separate correctly. It was a white logo that knocked out of a solid spot color background. The file looked right on screen, and the proof print that we made looked fine. But on the plate, the logo disappeared. The culprit? The logo, which was filled white, was set to overprint. I remember thinking at the time "who in their right mind would ever set white to overprint?"

A few days ago, I was designing a piece for a client when I wanted to place the company logo and knock it out of a colored background. So I opened the original black logo in Illustrator and changed all black-filled objects to white. Then I saved the file out with a new name and placed it into InDesign. However, upon placing the logo in InDesign, the logo itself was invisible. And then it all made sense:

1. I had Overprint Preview turned on in InDesign (I wanted to see a better interpretation of the Metallic Pantone color I had been using for the background).

2. My logo had initially been colored black and was set to overprint when it was originally created.

3. When I changed the fill color to white, the overprint command was still applied to the object.

In reality, the fact that I had Overprint Preview turned on in InDesign is what saved me here. Otherwise I would have had no idea, and the job would have went to press that way. And because this is one of those crazy deadline jobs, I would have requested some quick proof print to sign off on -- and the composite proof would have shown the logo -- and then of course, I can just imagine the phone call I'd get from the client when the job would be delivered.

Illustrator CS2 does have a feature that allows it to detect when you've specified an overprint for an object that is painted white (as seen below), but this happens only when you're applying the overprint -- not as in the case above where the object already had the overprint, but the color was changed from black to white. I would assume that in the real world, this is the real cause for the problem we're dealing with. I think people are smart enough to know that white shouldn't be set to overprint.

So I was really happy to learn that there *IS* something out there that offers some kind of help. It's called WOP2KO, and it's a plugin for Illustrator CS2 from Worker72a. The non-abbreviated name of the plugin is White Overprint to Knockout.

Here's a description which I've pulled from the Worker72a website:

A fast, efficient method for preventing problems on press caused by white art and text objects incorrectly set to overprint. It takes only a few seconds and pays for itself with the first problem it catches.

How does it work?

- Open a Document.

- You will find the "Set White OP -> KO" command under the Object menu.

- The active open document will be scanned for text and path objects specified as 0% CMYK or 0% tint spot or global color fills or strokes that have been set to overprint. This includes locked or hidden art and art on locked or hidden layers. All overprint whites will be set to knockout.

- Please Note: Spot or Global swatches that have been defined as 0% CMYK will not be set to knock-out except in cases where an object also has a 0% tint value. To include 0% CMYK defined swatches, temporarily redefine them as non-global process color swatches before running WOP2KO.

It seems the plugin is Mac OS only at this point.

If you've ever been bitten by the white overprint issue before, I think you'll find that 25 bucks is a small price to pay for a good night's sleep the night before you go on press.

By the way, I should mention that I really think this is something that Adobe needs to address directly within the application. While the plugin is a good workaround, I'd much rather see some intelligence or feature built in that will help avoid these kinds of issues in the future.


Anonymous said...

Ah yes, I've learned this lesson the hard way too. It happened exactly the same way... (even with the phone call) Now I send out certified PDF files and use the 'remove white overprint' action list to make sure there's no white set to overprint. Enfocus Instant PDF checks the PDF, removes any white and notifies me.

By the way InDesign is smart enough to not maintain the overprint if you change the color of an item with overprint to white. Nice one!

Anonymous said...

That plug in is for MAC OS's only. Thats a dissapointment.


Mordy Golding said...

Thanks for pointing that out Jacob -- I didn't notice that. I'll update my post accordingly.

khiltd said...

I agree that Illustrator doesn't make it easy to track down problems like this, but there are plenty of legitimate reasons why you'd want to set white to overprint, most of which involve white ink.

Mordy Golding said...

I completely agree. Maybe I should have been more clear -- I mean process white. But you are correct in that there are uses for spot color whites and overprinting. The behavior I'd like to see is where Illustrator will disable (or turn off) overprinting for process white attributes.

khiltd said...

What'd be even more awesomer is if there were a way to magically designate a swatch as "always overprint" so that anything filled or stroked with that color would automatically do the right thing. I can't count the number of times I've designed something that needed to be printed on both white and colored substrates (t-shirts especially) and had to go back and redo/rethink portions of the design in order to get everything to work both ways. Some RIPs take care of this kind of thing automatically, but not everybody has them.

unit.seven said...

Hi Mordy - first comment. This is a great resource you offer, thnaks.

Yes setting a global swatch to overprint, knockout or 'no setting' would be a great feature IMO.

We did once have to use overprint process white when running maps from a CAD package microstation. We were running the base roads, forests, rivers etc as one pdf file which was then rasterized and running the text and symbolds as another pdf file which was kept as vector. These were then placed togeather in Indesign. As we wanted to mask some base features behind the text for clarity but needed the text off we just set all text and symbolds to o/p white - magic, invisible text that the app would still recognise and use to mask the layers we wanted masked.

Also there are a lot of people out there who don't know what overprint is or when to use it correctly which adds to the problems.

Mordy Golding said...

khiltd - extra points for using the word "awesomer"!

unit7 - glad to have you aboard! I do have a frank and in-depth discussion about overprints on page 413 of my book, which was also published as an entire article in an issue of InDesign magazine. Maybe I need to rent a helicopter and drop flyers over major cities too? :)

John Kallios said...

"And because this is one of those crazy deadline jobs, I would have requested some quick proof print to sign off on -- and the composite proof would have shown the logo -- and then of course, I can just imagine the phone call I'd get from the client when the job would be delivered."

Even those quick composite proofs by ANY print vendor should operate that composite proof through a process of room. (rip once, output many)

Even if the printer was outputting to a desktop inkjet, they should simulate overprints in their output.

If they don't do this, you can never trust their proofs.

Doug Habben said...

Hi Mordy and everyone.
I have just posted a freebie - White Overprint Detector - at worker72a.com. It is an AI CS2 plug-in for Mac that automatically scans CMYK documents when opened and alerts the user if white overprint text or paths are found. It doesn't remove the overprints. Hopefully folks will be kind enough to purchase WOP2KO if they want to quickly and easily do that. But, just being warned of a potential problem is the most important thing, no?

Best Wishes,
dh - w72a

Anonymous said...

Hello mordy, the white overprints is new in illustrator? i had this kind of trouble working with freehand, and it was my primary reason to move to illustrator in version 5, that didn't overprint the white (maybe i'm wrong). For designer that don't uses too much white ink, cmyk enviroment, it can be a headache have another thing to check out before send it to press.

Ernesto Avila

Peter Houe said...

Hey, finally I found the explanation for my white knockout problem. I had a white ill. object in an Indesign document, that disappeared in printing.
Preflight only told me I had to turn on knockout for a white object. THere is no such command in Indesign.
Your post made me realize, that the problem was exactly as you describe - the Ill. object was originally black with overprint on, and had been changed to white without turning overprint off.

Anonymous said...

AH Once bitten..(try a spot color thats supposed to have a tiny legal print knocked out of it and the copyright and reg circles (circle c and r) are set to overprint then run about 50,000 or so units..ARRRGHHH)
. This is a good reason to leave your attributes window open...and just before your last save: lock down all your overprint parts and then select all.. Does your overprint fill button get a - in it or a check mark? click on it so its empty... no more accidental overprints of stuff you need knocked out. (oh and CURSE you designers who make white using 0% black (k)...)

Mr said...

Thanks for posting this. Had the same problem in InDesign CS3. And I have been gnashing my teeth for hours. You saved me a lot of grief.

Anonymous said...

Thanks for solving the mystery of why the 1000's of business cards I have just got printed for my client have a spot grey overprinted on a yellow, and white text has simply disappeared. It's a shame the printer didn't check the film against the proof...

I have checked the illustrator created logos supplied to me by the client which were created by his previous designer and lo and behold, the grey and white have the 'overprint fill' box clicked!

As you have to physically click the box (you can't do it by mistake), I am beginning to believe the previous designer purposely sabotaged the artwork so that this problem would occur if anybody else used the artwork he has created.

Phil UK

rachel said...

Yep, happened to me today in the same way.

Jack said...

In CS4, for sure, you can clear appearance. Then re-apply white as you need to.

Tom said...

I can't thank you enough for the info. I had a pesky drawing with a million clipped paths and couldn't find the culprit. I knew he was there because of preflight in acrobat.

I searched the internet in desperation and found your post and fixed it all in 10 minutes!

Thanks again,


mike said...

Fact is, Illustrator is a total piece of SH*T. The only reason that people use it is the total lack of any credible alternative now that Adobe have effectively killed FreeHand off. FreeHand was a truly intuitive Vector Drawing package -- Illustrator is a pretender -- a pale imitation.