white CMYK overprints

[motormount]

Could be any reason for a designer to set cmyk white overprinting on purpose?

 

[Gatekeeper]

Gatekeeper for pdf

Gatekeeper for pdf

Could be any reason for a designer to set cmyk white overprinting on purpose?

hi there

in most cases you type in black text which is set to overprint within the application the designers work with. they would then set the text to white but forget to knock it out........just a scenario

 

[yavo]

Hi

This is a mistake .
Sometimes could be forgotten the ignore overprint.
Could be done warning the some pluging artwork when opened.
esko, wopd..

 

[toronar]

This can be intentional as well:
White text, apply drop shadow, set white text to overprint, only drop shadow remains.

 

[motormount]

Thanks for answering.

I'd like to know if there is some case were you need to turn overprint on for a white object.

I'm not talking setting a white object to overprint by accident/mistake.

The only one i could think of is marking a cutter with cmyk white to stand out if the illustration below is too dark.

Is there any other reason you can think of?

Thanks in advance!

 

[motormount]

Thanks toronar,we were writing at the same time i suppose.

I'm asking because my prepare sequence is set to knock out whites,and i was wandering if i may get in trouble with that!

 

[toronar]

I don't remember in which cases this happened, but transparancy flattening can produce white objects with overprint as well, and setting those to not overprint will be trouble.

 

[Stephen Marsh]

When dealing with a print white ink in say packaging, it is generally necessary to place it above all other artwork (CMYK or spot) so that the other content does not knock out unwanted holes into the spot white. Print white not set to overprint or multiply will of course knock out and remove the content below, so the spot white is then set to overprint so that underlying artwork is not adversely affected. This is wanted and by design for spot print white ink.

If there is no print white separation required, then there are less common cases where an overprint white is intended, in most cases it would be a mistake.

Probably best to flag/warn this in preflight without changing the setting if this is a concern. Many prepress workflow systems and RIPs are set to change overprinting whites, which is a safe assumption – except for when it isn’t :]


Stephen Marsh

 

[Glenn McDowall]

faux transparancy .
if you wanted to darken a spot colour or cmy you could set a black to white gradient to overprint, perhaps with a large area of white. You could then export to pdfx 1 or 3.

I also once created a pdf with white text set to overprint reading "If you can read this text then your Acrobat Overprint Preview settings are incorrect"

 

[dabob]

I just copied and pasted this from "hardest files thread" but it applies here also . . .

Well . . . I can't remember all of the files I've fixed . . . but to my memory the hardest job was a label for a nutritional supplement company who wanted their premier product label to be something special - they brought in a piece that was printed on a silver foil laminated to a board backing and then die cut into a box . . . but these were labels for a large bottle . . .And they wanted some of the colors to be pure (to match the PMS book in process color) for logos and such but they wanted the background to have a metallic look.

1st we had to find the paper, finally found somebody 2500 miles away that could laminate the foil to a label stock and then sheet it for us (a 19x25 inch sheet ran us about $1 each)
2nd we had to figure out how to attain the pure pms color on a silver stock . . . that took a double hit of white ink where these objects were and we had to use a two step trap on the files 1 for the white printer( really fat) and then regular trapping for the process work
3rd running multiple press tests to get the metallic color they were shooting for on the process work

Well after about 6 months of research we figured it out . . . and then after a couple of years they said they cost too much and just went to white paper . . . go figure

So if you are trying to get a "pure" color on a non white substrate that would be a reason . . . but in my case, in order to see it I created a buttugly green and called it white . . . otherwise how would you ever see what was "white"??????

 

[Simon Ivarsson]

First I would like to clarify on thing.
C 0% M 0% Y 0% K 0% is not white.
In knockout the substrate will be visible, In overprint it has no effect at all.
If such object is found its most defiantly a mistake and should be reported / confirmed with the creator of the file.

White is a ink, just like any other and should be treated just like any other ink.

 

[motormount]

Thanks all for your valuable answers!

 

[rich apollo]

motormount,
I routinely use that same step in my preflighting.

Most of the Adobe apps won't allow you to set white elements to overprint now. You have to do it in a round-about manner.