A few posts ago I had mentioned Nick Hoodge's wonderful InDesign Prepress Tips site. I used it to confirm the results I was gettting.

The problem with many two-color jobs - especially for printers using duplicator-class presses - is tight registration. On a newsletter, for instance, factors like 'tail whip', grain direction, and humidity can drive press operators nuts. Plus, many unseasoned graphic artists create designs that work in theory but are almost impossible to print on a printing press. Places where two colors touch each other show gaps, revealing the color of the paper underneath. It compromises the design and quality of any printed piece.

To address this, trapping is used. Basically, where colors touch, one color is widened so it prints over another color. This creates a 'margin of error' that helps offset many of the effects above. It makes it easier to get colors to touch; jobs look better.

In my instance, the printer I'm am working with has a nice Quickmaster, but whines if you push him or his abilities. REMEMBER: A printer will almost never tell you he'll struggle with a job. You're only indication will be when the job comes back and even the samples on top look shitty.

Anyways in pre-flighting the file handoff, I wanted to make sure there wasn't going to be any issues. An area needed to be trapped - so I used Adobe's In-Application trapping along with it's In-Rip Separations feature to print a postscript file.

Distill the postscript and open in Acrobat. Click 'Preview Overprints' and zoom it. Viola! A gauge on the trapping.

The PDF is a composite, but still retains its spot color information. Crackerjack can print the seps...