Printing Process Explained: The 5 Stages from Artwork to Finished Print

Printing—known in the trade as Graphic Arts, or Graphic Communications when the emphasis falls on visual messaging—describes a family of technologies that move ink onto paper, textiles, leather and other substrates through plate making, inking and pressure. The result is volume reproduction of original text, pictures and photographs. In practice, the workflow is usually broken down into five stages.

1. Selecting and analyzing the original (or creating one)

The original is the starting point and the reference point for the entire image-reproduction chain; in most cases it is text and graphic information carried on a physical object or medium. Because originals differ in type, the plate-making and printing method has to be matched to them—only then can the printed sheet stay faithful to the source and reproduce its text and tonal values quickly and in large quantities. Printed originals fall broadly into text originals, picture originals and photographic originals. More recently, some operations have begun separating colors directly from physical objects, which removes both the cost of photographing an original and the tonal loss that comes with it.

1. Design, production and proofing

Design and production means taking scanned images, or ready-made image files from a library, adding graphics and text, and laying everything out to match the client's intent—then turning it into a complete, output-ready file. Files are prepared differently depending on whether they are headed for offset printing, screen printing, other printing methods or inkjet output. The software normally used includes Photoshop, Freehand, Illustrator, CorelDRAW, PageMaker and QuarkXPress. Finished designs are generally checked against an ordinary inkjet proof sent to the client, or reviewed by the client on site; an inkjet proof should not need more than two rounds of correction. Before a file moves on to film output and printing, a proof is usually required—digital proofing can produce a sheet that matches the final printed result. Digital proofing calls for a dedicated imitation coated paper; other papers cannot be used. Its advantage is that proofing happens before film output, so any error can still be corrected and the film is guaranteed to be right.

1. Film output

When film is output for printing, proofing is usually still part of the routine. The film itself, however, is non-negotiable: it is essential for matching color on press, and without it printing is impossible. Only once the film exists can a PS plate be exposed and printed products produced. Film output breaks down into four steps:

(1) Once the file is finished on the computer, add color bars and corner marks (where many colors are involved, remember that corner marks must use registration color);

(2) Export the finished file as a PS file, or save it in a RIP-readable format such as EPS;

(3) Use output software to rasterize the file into a bitmap, then output the film;

(4) Collect the result from the developing section of the film processor.

Choosing the right substrate (paper or another printing material) and ink is only part of the equation—the final quality of a printed product also depends on selecting a suitable printing method. Printing comes in many varieties, and each method brings its own operating procedure, cost profile and visual result. Methods can be classified by the relative position of image and non-image areas on the plate, by the way the press feeds sheets, or by whether the plate makes contact with the substrate. Among the most common are offset printing, flexographic printing, screen printing and gravure printing.

1. Post-press finishing

Printing technology is a systems-level undertaking, organized into three major processes: prepress, printing and post-press finishing. Post-press finishing is the umbrella term for the production techniques that give printed sheets leaving the press their final required form and performance. How simple or complex that finishing work is varies enormously from one printed product to the next.

The printing process involves many steps and has to be managed step by step—an error in any single link can leave the finished product defective. A truly refined printed piece places strict demands on text, images and layout alike.

—Reprinted from China Packaging Network (pack.cn). Original article: http://news.pack.cn/show-361792.html