Specify the color as global in Illustrator in he swatcdhes palette, amek sure all your strokes and fills are aassigned the gloabl color.
On the future you need just edit the values in Illustrator, the cmyk values will update in quark when you import or update the link.
Thanks, but I'd need it the other way round ...
You could save your art as a grayscale tiff in Photoshop and apply the color in Quark. Normally I would try to keep vectors whenever possible, but depending what your art looks like, and if you choose an appropriate resolution, a tiff will look ok.
Luke is right, grayscale tiff is the only way you wil make this work.
There is another option that will maintain vectors I just remembered. You will need to invert your logo so everything you want to print in the variable color will be transparent. Save it as a PDF compatible .ai file. Quark 8 and 9 will let you place an .ai file saved this way. Quark 7 will place a .PDF. Quark will let you change the color of a box but will only let you change the color of the item in the box if it's a greyscale tiff. So what you can do is place your transparent .ai file into Quark and change the color of the box showing through the item. When exported as a PDF or postscript, the vectors will be preserved.
Thanks everybody for the replies. I'll try a couple of things later, right now I must work on a more urgent problem. Anyway:
The graphics are pretty simple, a simple linear blend (over several combined background objects) in one colour from 0% to 100%, overlaid by some simple knockouts and 100%-colour objects. I guess it wouldn't be too hard to recreate all this within XPress, if it wasn't for one catch: the midtone of the blend is not in the middle of the grafic but shifted to one side. XPress doesn't offer an option to adjust this.
As for the solutions with Tiff: There are two points witch make me hesitate placing the graphic as a Tiff:
First, to be sure that the graphic will be crisp everywhere, I'd have to chose a pretty high resolution (higher than the standard halftone 300 dpi). This would inflate the size of the grafic from a couple of hundred kB to hundred MB per graphic. Doable, but not nice.
Second and more important: I must be absolute sure that the knockouts are white and the fulltones are fulltone. I fear that the Tiffs would be "corrected" to 2% – 98% or somewhat like this in the process of generating plates.
Another idea: Does somebody know of an XTension which allows more control of blends?
Save as .eps or .pdf from quark, place that in illustrator, you will then add any new swatches or get an option about merging swatch colors with same name. If you end up with 2 different color swatches for the same color, use swatch flyout menu >> merge colors.