Publisher can print either 4 color or spot color jobs to film.
We recommend carefully creating your colors in the color palette.
Publisher will "average" colors and assign new values for them if you are printing a spot color job, but do not specify which spot colors first. Use the Commercial Printing options and select spot color ahead of time.
For Example: If you use 2 solid greens; plus black -- Publisher will make one green solid; and the other one a screen of green.
Be sure to include all your placed graphics even though Publisher may embed them.