Overprinting - what my mom never told me.

[GAC05]

Hi all.
I've been printing for a few years now and didn't know what overprinting was or that I even needed to know anything about it.
Lately I have been getting some client AI files that have had random white elements drop out when printed.
Digging into the file showed those objects had their overprinting flag set on.
Quick google search and it turns out to be an issue with white fills.
Illustrator warns you if you try to turn on overprinting with a white object but does not warn you if it has been turned on by someone else.
(Looks like Indesign has a preflight check for this that Illy lacks)
I know now to turn on the overprint display mode and see what disappears before sending something on to the RIP.
The Program Manager in Flexi(8.6) has a check box to ignore overprint that is on by default.
It does not seem to have any effect on this issue on or off so, maybe "ignore overprint" means it does not care if the flag is set or not.

From this I have learned that I still have large holes in my wide format education and that Google can make me seem smarter than I am.

wayne k
guam usa

 

[Custom_Grafx]

I have had issues once or twice with this.

There were two 'blue' elements but they printed differently. We soon found out that one of them had "overprint" set to on.

If you have Illy set to overprint preview (view menu), you will see the appearance. In your print dialog, if you set overprints to "simulate", it will print the same as what you see.

If you are in normal preview mode, and you want to print what you see on the screen, ignoring any overprint settings on objects, you should select "discard" in your print dialog.

By pre-flight, the flattener preview (window/flattener preview) box will give you a preview of different overprint settings. Pressing the 'refresh' button is required.

In the print dialog, it will also notify you in the 'summary' section if there are any objects which contain overprinting.

 

[Custom_Grafx]

And also... if you go to 'separations preview' in the window menu, you can see what happens with flattening and transparency and overprinting by switching printing plates on and off.