Adding white and primer underlayer on illustrator and export to pdf

We checked with the supplier from the RIP software and decided to solve this by treating the primer/white as full coverage layer instead of assigning it as spot color. The rip software reduces this to the actual printing area. In allmost all cases the primer and white need to cover the whole surface, which is clipped to the actual printed area by the rip software.

So no longer the need to solve this in the PDF / Illustrator file itself

How about preparing some exapmle files instead of describing this? Upload this as a package to Dropbox or the like with some clear instrauctions of what is to be aachieved.

That way nobody has to guess about it and doesnÄt have to build this themselves.

I hope I understand what you want, CMYK and 2 spots that get not erased by the CMYK plates when separated?

Place the customer PDF linked in an Illustrator CMYK document.

Select the PDF and use Darken blend mode in the Transparency panel.

I would create 2 white spot colors and give them names like primer and whitespot.

Fill 2 squares set them to overprint and put them below the linked PDF.

Yep, you have to isolate all the individual colors so that no color is overprinting another.

Do a save as on supplied art, then select all → pathfinder→divide then trim then merge.

Then select all, overprint, and place in your primer and white.

Note this only works for pure vector, if you have any transparency or any pixel art, you need to isolate those parts and work on the overprint separately.

A screenshot, even a cropped one only showing a small corner of the problem along with the opened layer stack would do miracles. On a hunch I'd say itr is merely a matter of isolating the group via the transparency options or separations, but it's really hard to tell and my brain just melts imagining it.

Mylenium