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1. Re: White overprint - Why does it exist?
Mike Gondek2 Dec 1, 2011 1:10 PM (in response to Prepress labels)I agree white should not be allowed to overprint and have felt that way for a long time.
We do though take advanatge of that sometimes and make our bottom layer the varnish plate, and set the white to overprint.
You can select all, and turn off overprint. The problem is if you have images, you cannot just hide of lock them and select all to remove overprint. You can though select just the images, select inverse, then turn off the overprint in the attributes panels.
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2. Re: White overprint - Why does it exist?
Steve Fairbairn Dec 1, 2011 2:23 PM (in response to Prepress labels)White overprint was for a long time not allowed in Illustrator. It was there in Illie3 but had been taken out by Illie5 owing to many complaints from users..
It only returned with the advent of transparency effects (around Illie9 or thereabouts, I think) which had up till then only been (sort of) possible by overpreinting.
Of course overprinting white is a nonsense and an annoying one at that - except of course if you want to overprint a spot white, in which case it is extremely useful (for example if you need to print with a white ink on a transparent or metallic substrate).
It caused us several mistakes to start with - where white lettering was visible in pdfs but "strangely" didn't knock out the background colour.
The trick, as we discovered after some expensive reprints, was to make a rule of carefully examining all artwork with Overprint Preview turned on.
Following that take a good look at separations in Acrobat.
Arguably Overprint Preview should be the default, but the disadvantage of having it turned on all the time is that it slows things down quite considerably. Colours are more accurate but at the expense of speed. This can make a great difference if you are using lots of effects and have many placed images.
In my opinion Adobe could well disallow process white overprinting like they did previously. I can see no use for it.
Transparent white can though be used to good effect with Normal, Screen, Lighten, Colour Dodge etc.
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3. Re: White overprint - Why does it exist?
Monika Gause Dec 1, 2011 2:52 PM (in response to Steve Fairbairn)There is a statement by Teri Pettit, why it is there at all:
http://www.mombu.com/computer_design/illustrator/t-white-overprint-why-4277107.html (3rd Post)
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4. Re: White overprint - Why does it exist?
Steve Fairbairn Dec 1, 2011 4:21 PM (in response to Monika Gause)"The only practical use of overprint would be setting a SPOT white ink to overprint, such as one would use in silkscreening."
Or flexo. Or gravure. But only spot white.
Overprint on CMYK white is nonsense because the white there is the PAPER!
Have you ever tried overprinting paper with paper?
The result is cardboard :-)
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5. Re: White overprint - Why does it exist?
Jacob Bugge Dec 2, 2011 3:42 AM (in response to Prepress labels)Actually, the first part of the post by Teri,
The only practical use of overprint would be setting a SPOT white ink to overprint, such as one would use in silkscreening.
was merely a repetition of the previous post by John, then followed by:
Not true. In Illustrator 8, we made it impossible to set process white to overprint, and restored the ability in Illustrator 9, mainly at the request of packaging customers like Coca-Cola and Mattel.
The main application is when making an object blend that is meant to go from white to some process color, and then overprinting that blend onto a colored background. If you can't set the white to overprint, it will caused unwanted knockout of the substrate color.
In AI 8, customers had to work around this problem by applying a very small amount of any process color channel that existed in the object being blended to to the nominally white object, so that the blend was between, say 1% cyan and 1% black to 100% cyan and 50% black, instead of from white. They resented having to do this, especially since they had files made in earlier versions of Illustrator that had to be modified in order to print correctly.
Apart from that, the discussion went on, about the continued justification in new(er) versions.
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6. Re: White overprint - Why does it exist?
Prepress labels Dec 2, 2011 6:49 AM (in response to Prepress labels)Thanks--lots of good feedback here. It sounds like it simply started out that way in the early versions, then when it was disallowed, it negatively affected legacy files (where people were using white overprint to achieve a desired look), so it was restored, and that's just the way it is, and possibly the way it shall be.
So why was it allowed in the first place? I'm guessing it's just because all those years ago, the application wasn't perfect.
If you were designing something from scratch with the current Illustrator, is there any situation in which white overprint is the only way to achieve a desired effect? I want to say no, but I'm not really a designer--let me know what you think.
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7. Re: White overprint - Why does it exist?
Steve Fairbairn Dec 2, 2011 9:19 AM (in response to Prepress labels)If you were designing something from scratch with the current Illustrator, is there any situation in which white overprint is the only way to achieve a desired effect? I want to say no, but I'm not really a designer--let me know what you think.
Like I said, it is useful to be able to overprint a spot white.
Say you are making a design for printing on a metallic substrate like a beer can and only have transparent coloured inks available.
You need an opaque white to block out parts of the substrate to make parts of the colours opaque (or non-metallic).
Instead of putting the (spot) white at the bottom of the layer stack with the accompanying nightmare of putting overprints on some but maybe not all of the other colours, you put the white on top (maybe even on a separate layer) and set it to overprint. You just select overprint preview to check that all is well.
Check the separation to make doubly sure that everything is as you want it and Bob's your uncle. The plates will be o.k. even though the drawing is not stacked in what might seem to be a "logical" order.
I understand what Jacob says but have personally never had the problem he quotes and, as you can read in his post, there is a workaround. The re-introduction of overprinting on process whites was not well enough introduced at the time, causing distress and expense to many. Personally I have no use for it.
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8. Re: White overprint - Why does it exist?
Prepress labels Dec 2, 2011 9:28 AM (in response to Steve Fairbairn)I agree--overprinting a spot white has never been a problem for me (we do spot white all the time, and I just put it in a layer above the other art, with all of the spot white overprinting).
But you're right--when it's process white in the art file, and it's set to overprint, that's pretty much the same as having nothing there, at least in the printing world.
Thanks for all the feedback!
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9. Re: White overprint - Why does it exist?
EDI RITOSA Jul 3, 2014 1:33 AM (in response to Prepress labels)Just recieved phone call from the press house.They will throw away 5000 brochures because of the issue mentioned, needless to say who wont get paid for the design, and will have to pay additional expences.
There is absolutley NO PRACTICAL REASON FOR WHITE OVERPRINT... That is bad, unnecessary, useless, meaningless, and 1 more thing to be freightened of if you work as a designer.
Not only white likes to go to overprint, but also black is not 100%K most of the time.
This is absolute disappointment.
I've worked in press house for 5 years, and only in 2 situations is colour set to overprint.100% BLACK (text - most common), and 5th color.
Very nice job adobe! (clap, clap!!!)
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10. Re: White overprint - Why does it exist?
Danny Whitehead. Jul 3, 2014 5:24 AM (in response to Prepress labels)I'll add another vote for the removal of the ability to overprint process white. If you want a spot white, add a spot white.
InDesign's irremovable [Paper] swatch functions much better for print work.
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11. Re: White overprint - Why does it exist?
Monika Gause Jul 3, 2014 5:48 AM (in response to Danny Whitehead.)From Illustrator CC on, White overprint can be automatically removed in output files.
That's a setting in "document setup"
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12. Re: White overprint - Why does it exist?
CHMprepress Jul 3, 2014 6:33 AM (in response to Prepress labels)I have been in the Prepress packaging industry for almost 25 years, lets say I have seen it all:=)
The only advice I can give you is to avoid all overprints and to use transparanties instead.
Overprint you talk about is old postscript language, modern WF's and RIP's handle full transparencies files better than postscript.




