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Prepress

Prepress Department

Proper File Preparation: Key to a Successful Printing Job

Prepress is a term used in the printing industry to describe the process a file must go through before it can be printed. Each of the following steps is a critical part of a successful printing outcome. Having your file properly prepared streamlines the printing process. If you have any questions, please call us—we'll be happy to help! 

Proofreading

In the prepress department, we work very hard to ensure complete and total accuracy of each and every job. Proofing is the final review of your project before it goes to press. Proofing is done to catch human errors and errors produced by bugs in programming code from a computer. If errors are caught, then that proof is sent back to the responsible party for corrections. A susequent proof is done to ensure that the final version is correct. Client approval is mandatory before a job is printed. That's why we always ask you to approve your file before it goes to press. 

Layout

There are several specifications and elements to include in your layout to insure that your final project will print as you intended. Here are a few that you should know:

Trim Marks

Trim marks, or crop marks, show where to cut the paper. Since you don’t want these lines to actually show up on your printed piece, trim marks are placed outside of the final visible, or “live,” area.

Bleeds

Many designs have images and other design elements that extend all the way to the edge of the printed page. In your layout, if these elements only extended to the edge, and not beyond, you would risk a tiny bit of white space showing up on the edge of your paper if it was not cut exactly on the trim marks. The amount that your images need to extend beyond the trim marks is called a bleed. Bleeds are images that extend beyond the live area of the page (and beyond the trim marks) to guarantee clean edges. Background colors are an example of a common use of a bleed.

Imposing

Commercial printers often use large sheets of paper that they fold, cut, and trim to the finished size. The individual pages may not be printed in the same order that they will appear in the finished document. Getting the pages of your digital document from reader's spreads or reading order (page 1, page 2, page 3, etc.) into printer's spreads or printing order is called imposition.

Imposition for printing can reduce paper waste and save money on some printing jobs.

Color Separation and Plating

In order to print color files on an offset printing press, we must first separate the color image into the four basic ink colors: cyan, magenta, yellow, and black (CMYK). Each single-color layer is transferred to a printing plate, and then printed separately, one on top of the other, to give the impression of infinite colors. 

Plating

Offset printing is done with printing plates. An image (your job) is transferred to a printing plate or plates, which can be made of a variety of materials such as metal, rubber, or paper. Each plate is then chemically treated so that only the image areas (such as type, colors, shapes and other elements) will accept ink.

Water and ink is then applied to the plate. Because of the chemical treatment, the ink only "sticks" to the image areas, which reject the water. Areas without images reject the ink. The plate is then rolled onto a rubber cylinder applying the inked area, and in turn the rubber cylinder  applies the image to the paper. The term "offset" for this form of printing is used because the plate does not come in direct contact with the paper.