[HAWLEYJ] “I notice my red actually shows up in both the Magenta and Yellow channels. Should I still just do the Magenta thing and tell them about it?
Red = magenta plus yellow, which is why you’re seeing the stuff on both channels. If your red was set up as 100% magenta plus 100% yellow (and shades thereof), then just deleting the data in the yellow channel (or telling the printer not to image that channel) will do you fine – anything that was 100% of your red will now be 100% magenta, etc. But it’d probably be better to actually make the objects the magenta – if, say, you had a shape that you expected to be 50% of the red, then set it to be 50% magenta instead. For raster or photographic layers, see below.
[HAWLEYJ]Also, how do I “redefine those items as 100% black instead.”??”
Bring up your color picker and manually type in 0% for Cyan, Magenta and Yellow and 100% for black. For vector or type layers, all you have to do is hit alt or option delete, and it will fill the shapes/text with 100% black.
For non vector layers, it’ll a little tricker – here’s a quick and dirty way (make a backup of your file first). Hide any of your red layers so you don’t mess them up, and hide the black vector or type layers. Merge the remaining layers together, so you have one layer with all your greyscale photographic stuff. Select all and copy merged.
Then make the Cyan channel active (either in the channels palette, or by hitting control-1 or command-1). Clear the channel by selecting all and deleting. Do the same thing on the Magenta and Yellow channels (Cntrl/Cmd 2 and Cntrl/Cmd 3). Switch to the black channel (Cntrl/Cmd 4). You’ll see your image, but it’s lost all the midtones, because those were being taken care of by the CMY channels which you deleted. Select all and paste – you just pasted the composite CMYK image into just the black channel. Go back to your composite view (Cntrl/Cmd tilda) and adjust the levels a bit to get it looking how you want it (usually you’ll want to boost the darks). Now your greyscale stuff is only in the black channel.
You can do the same thing with your red photographic layers – with only red layers showing (agan, hide the black layers, and hide any red vector or type layers – you can take care of those manually). Select all and copy merged. Then delete everything from the Cyan, Yellow, and Black channels. Switch to the magenta channel and paste.
Let me know if something doesn’t make sense. It’s a lot all at once….