Here is the quick & dirty version of how I occasionally sep out spot colors…with the Channel mixer…

Basically if you want to use a simple method…

in Photoshop CS,CS2,CS3…whatever just go to your channel mixer,
which is under the top menu (image / adjustments / channel mixer)
check the monotone box, and pull out your other info, with the sliders…

Then adjust the curves if needed…make the blacks that should be 100% actually 100% and not 97% or something.

Save in greyscale…add you line/screen/dot numbers if needed.

It works best if you are working with some sort of layered file…so you can easier isolate the elements you don’t need by knocking them out with the hue/sat tool….knock em out white or black…don’t just turn off the layer cause, well then the background will peek thru.
The actual numbers in the Channel Mixer aren’t really whats important, just how the file looks, every design will vary. So don’t just duplicate the numbers and think you have a perfect red film, ready to print on a tee.

This is just a regular flat RGB file for example purposes, but I did convert to CMYK on the yellow, since obviously the Y stands for yellow, and has the cleanest Yellow info…not enough info is lost since we are printing on shirts, on super low resolution….this can also be done with the Cyan channel….Blue, and even the Magenta, for Red.

This obviously works better with a layered file, and this is just really a quick fix / quick sep, if you need to pull out spot colors in a bind….it works great, but really if you want a perfectly separated ready to screen print piece of art, You have to create the art with that purpose from the start.

Although using this method is great, it really really helps to knock out the elements with the Hue/Sat Tool in a layered file with white or black or whatever your background color is.

That way you definitely know any similar color noise….won’t be in your selected color film…this is especially necessary with oranges/reds…like flames, or sunsets…but then again, I use an entirely different method when I sep those…maybe I’ll share, that method next.

Overall I think mixing up the different sep methods, works best.

Here are 3 screen shots…

the 1st is the original design…

2nd is the red spot pulled out.

and 3rd is the Yellow spot pulled out.

Real Quick Real Simple….But it essentially does the trick. YOu can easily further refine your spot color selection from here and make your sep even more precise, or take it right to press and see what you have already will work out.

Drew