Ok, I know this has been discussed before but I'm hopping to get an answer that touches more on the print methodology rather than the quirkiness of Illustrator when it comes to Spot Color representation.
I am preparing a playing card design (in Illustrator) to be printed by the US Playing Card Company. The card back design is supposed to be a single color over white cardstock. I originally worked up the design in CMYK using Pantone's CMYK formula for PMS 280c. There are gradients and outer glow effects applied to some of the vector elements in the image that are intended to just fade from the color itself to the cardstock which is essentially a white background.
At a certain point I decided it would probably be a good idea to do the design in an actual Pantone Spot Ink for color consistency in the event an additional run of the cards was ever printed. So I added a new swatch from the "Color Books-Pantone Solid Coated" and assigned it to all the elements in my design. I then realized that the Illustrator default when choosing from "Pantone Solid Coated" is set to "Process Color" instead of "Spot Color"...not sure why but that is beside the point.
Once I edited the swatch to be a true Spot color, all of the outer glow effects stopped displaying properly. Image #1 is CMYK and shows what I want it to look like when printed. Image #2 shows what happened when I switched everything over to the Spot Color Swatch. Image #3 is marked up to show what I am talking about.
The shadows in white areas of the design nearly disappeared ...whereas shadows in the darker areas turn to a hazy white that is not correct. If Illustrator is capable of showing it correctly in CMYK why can't it show correctly with a spot color? A Spot color would be applied to the card stock using a single plate just like any of the 4 colors plates in the CMYK process so I don't understand why it can't display the raster effects properly.
I realize part of this just has to do with how Illustrator displays Spot Colors over light or dark backgrounds. But my question is actually about what happens on the printer's end. US Playing Card Co. uses a fully digital process "Computer to Plate". How do I make sure the raster effects and gradients will be processed correctly for the single color plate. I want them to just be halftone dots amongst solids all on the same plate.
Is there a work around for this? One idea I had was to just set the file up as CMYK and do the design all in black. This allows for the gradients and outer glows to display properly. That way when they do Computer to Plate it would only spit out one press plate for the black "K" channel with halftones incorporated. Could they not just then run PMS 280c ink on that plate instead of black process ink?