We recently ran into a problem where white vector data from Abobe Illustrator is being interepreted by our rip as a 255,255,254 value when ripping the postcript file output by Illustrator. This results in a very fine c and m dot in the whites when the file is printed.
If we take the same Illustrator PS file, rasterize it in photoshop, and save it as a tiff, we can rip and print it and it shows up as a 255,255,255 value, and prints with no dot.
In both cases, the embedded profiles are the same (Abobe RGB), and the rendering intent is Relative Colormetric. The rip runs on a pc, and the Abobe programs run on a pc.
Anyone have insights into why this occurs?
I am not familiar with your particular issue but I can say that I only work in CMYK while in Illustrator if my final output is going to a CMYK press. I’ve never been a fan of working in RGB in Illustrator - since I don’t do web stuff.
Is it necessary that you work in RGB in Illustrator?
I’m gonna guess you’re too far vested in this project to do this but …
Perhaps work in CMYK and create a spot color swatch designated 0, 0, 0, 0 (CMYK)
I know nothing about your workflow or this project so please don’t take offense to that question or suggestion. 
What kind of RIP is this? Many RIP’s handle Vector data differently than raster data. I would be asking questions of the RIP.
C+M = B so there might be something hinky in the curve… Make certain that the 0 input value in your curves are truly outputting to 0.
When working in Illustrator for print I would definitely work in CMYK. If you are working in RGB, change the document mode to CMYK before RIPping.
Solution 1:
Save as PDF
Color management can be off.
All LINKS, including linked RGB scale, must have RGB adobe 98 profile embedded.
Under conversion in the print dialog, it should say No Conversion.
Solution 2:
Print as Postscript:
Color management must be on.
Under edit, Color setting change RGB to Preserve Emedded Profiles.
All LINKS, including linked RGB scale, must have RGB adobe 98 profile embedded.
Under file, the document mode should be RGB.
Under edit, Assign profile, the Adobe 98 profile should be embedded to the document itself.
You may test the results for yourself using Distiller set with color management set to Unchanged and Preserve.
