Illustrator adding overprint settings...WTF?

[ZooCity]

We just scrapped a nice pile of recycled/organic/u.s. made Ts.  How?

Well, we didn't notice that we were missing a knockout area of the image.  Once we realized, I checked the .ai file and the missing k/o was set to "overprint fill".  This is a one color image, there are not overprints going on and I am 110% absolutely certain I did not set this fill to overprint.  I also pre-flight everything, even one color prints in distiller and/or acrobat before filmoutput.

I'm primarily disappointed with myself as it's my fault for not catching it at pre-flight or on the pin lock table, etc. but seriously, what the hell would cause this?  The area that set itself to overprint was straight RGB white.  My one color image is in spot color with this k/o area over top. I have had this issue occur three times now and developed the pre-flight system to prevent it but still this crap sneaks through.  I suppose we could rasterize everything at high dpi or spend the needles hours cleaning vectors down into finished compound shapes...but there's got to be a better way.

[Sbrem]

sounds pretty bizarre, Zoo. I mean, I understand what happened, but not why. We usually proof to a laser printer, and I recently learned about Separation Preview (I've only been using CS5 for a year and a half, sheesh) though I've been too busy with recent poopstorms to dig in (no pun intended)...

Steve

[JBLUE]

Sep preview is your friend. I am no expert but I use that window dailey on stuff we sep out of  Illustrator. Works great or finding missing items of color.

[ebscreen]

Too many WTF's can happen in spes/printing, so we reduce all of our vector art to be essentially able
to cut out of vinyl if need be. IE no compound paths, no using colors to hide other colors, all strokes outlined, merged, etc.
Obnoxious but it's kept us out of a lot of trouble.

[chubsetc]

Had this happen in Corel with a font just 2 weeks ago, but it filled in the letters like p, b, d, on a 1 color print.  Had to convert the font to curves and then it printed fine.  Good thing I noticed it before I exposed the screens.

[ZooCity]

Yep, I used to do that eb but it's such a drag.  I'll need to regroup on this or maybe just suck it up and introduce more visual checks to the process.

What concerns me is how the hell overprint fill got checked on that k/o object....I agree Steve, that makes no sense.  Must be the adobe gnomes at it again. Extra weird: we ran this job before and the film printed fine.  All I did was grab the original final file and copy paste it into our new template.  I do need to check out sep preview, sounds better than outputting a .ps file every freaking time.

We're lucky my printer caught it before we hit the hoodies though!

[cvreeland]

The very first two moves I make with an Illustrator file is to expand everything, so no effects and no strokes -- just filled objects, then select everything & trim.

[Denis Kolar]

I get those every day at my regular job.
Who did the artwork? Usually, we have them supplied by customers.

[MrBreeze]

This stuff happens every day with files from customers.  Everybody has their own way of working in illustrator.  I see stuff I can't believe all the time.  As Illustrator continues to get more capabilities with every new release the opportunity for problems increases.  If we all have to move to the cloud and the updates can come literally on a daily basis it will be even tougher to keep up.  It's hard to do but take a deep breath and Proof, Proof, Proof.  Expanding the files always seems to help simplify things.

[Dottonedan]

Sounds like maybe the glitch came from the copy/paste and the (new file) had something about it that sets RGB white, CMYK whites aka computer whites or non custom spot colors to overprint. Maybe due to Adobe assuming that if you have a color in it, (at the starting point) you intend on that color printing...unless you manually tell it not to print. "Guessing.