The printing process has three stages: prepress, press, and binding or finishing. While workers in small print shops are usually responsible for all three stages, in most printing firms, formatting print jobs and correcting layout errors before the job goes to print is the responsibility of a specialized group of workers. Prepress technicians and workers are responsible for this prepress work. They perform a variety of tasks to help transform text and pictures into finished pages and prepare the pages for print.
Prepress technicians receive images from in-house graphic designers or directly from customers and see the job through the process of preparing print-ready pages to create a finished printing plate. Printing plates are thin sheets of metal that carry the final image to be printed. Printing presses use this plate to copy the image to the printed products we see every day. Once a printing plate has been created, prepress technicians collaborate with printing machine operators to check for any potential printing problems. Several plates may be needed if a job requires color, but advanced printing technology does not require plates.
For a long time, prepress workers used a photographic process to make printing plates. This is a complex process involving ultraviolet light and chemical exposure through which the text and images of a print job harden on a metal plate and become water repellent. These hard, water repellent portions of the metal plate are in the form of the text and images that will be printed on paper. More recently, the printing industry has largely moved to technology known as "direct-to-plate", by which the prepress technicians send the data directly to a plating system, by-passing the need for the photographic technique.
The direct-to-plate technique is just one example of digital imaging technology that has largely replaced cold type print technology. Prepress technicians known as "preflight technicians" or production coordinators are using digital imaging technology to complete more and more print jobs. Using this technology, technicians take electronic files received from customers and check them for completeness. They then format the jobs using electronic page layout software in order to fit the pages to dimensions of the paper stock to be used. When color printing is required, the technicians produce an electronic image of the printed pages and then print a copy, or "proof," of the pages as they will appear when printed. The technician then has the proofs delivered or mailed to the customer for a final check. Once the customer approves the proofs, technicians use laser "imagesetters" to expose digital images of the pages directly onto the thin metal printing plates.
Advances in computer software and printing technology continue to change prepress work. Today, customers of print shops often use their own computers to do much of the typesetting and page layout work formerly done by prepress technicians. This process, called "desktop publishing," provides printers with pages of material that look like the desired finished product. This work is usually done by desktop publishers or graphic designers with knowledge of publishing software. As a result, prepress workers often receive files from customers on a computer disk or via e-mail that contain typeset material already laid out in pages. Other more advanced technologies now allow prepress technicians to send printing files directly to the printer and skip the plate-making process altogether. Despite the shortcuts that technological advancements allow, workers still need to understand the basic processes behind prepress, press, and finishing operations. Some workers, known as job printers, perform prepress and print operations. Job printers often are found in small establishments where work combines several job skills.
Work environment. Prepress technicians and workers usually work in clean, air-conditioned areas with little noise. Some workers may develop eyestrain from working in front of a video display terminal or other minor problems, such as backaches. Those platemakers who still work with toxic chemicals face the hazard of skin irritations. Workers are often subject to stress and the pressures of deadlines and tight work schedules.
Prepress employees usually work an 8-hour day. Some workers—particularly those employed by newspapers—work night shifts. Weekend and holiday work may be required, particularly when a print job is behind schedule. Part-time prepress technicians made up 12 percent of this occupation in 2006.
| 1. | Enter, store, and retrieve information on computer-aided equipment. |
| 2. | Enter, position, and alter text size, using computers, to make up and arrange pages so that printed materials can be produced. |
| 3. | Maintain, adjust, and clean equipment, and perform minor repairs. |
| 4. | Operate and maintain laser plate-making equipment that converts electronic data to plates without the use of film. |
| 5. | Examine photographic images for obvious imperfections prior to plate making. |
| 6. | Operate presses to print proofs of plates, monitoring printing quality to ensure that it is adequate. |
| 7. | Monitor contact between cover glass and masks inside vacuum frames, in order to prevent flaws resulting from overexposure or light reflection. |
| 8. | Transfer images from master plates to unexposed plates, and immerse plates in developing solutions to develop images. |
| 9. | Examine unexposed photographic plates to detect flaws or foreign particles prior to printing. |
| 10. | Lower vacuum frames onto plate-film assemblies, activate vacuums to establish contact between film and plates, and set timers to activate ultraviolet lights that expose plates. |
| 11. | Examine finished plates to detect flaws, verify conformity with master plates, and measure dot sizes and centers, using light-boxes and microscopes. |
| 12. | Perform close alignment or registration of double and single flats to sensitized plates prior to exposure, in order to produce composite images. |
| 13. | Remove plate-film assemblies from vacuum frames, and place exposed plates in automatic processors to develop images and dry plates. |
| 14. | Position and angle screens for proper exposure. |
| 15. | Inspect developed film for specified results and quality, using magnifying glasses and scopes; forward acceptable negatives or positives to other workers or to customers. |
| 16. | Punch holes in light-sensitive plates and insert pins in holes to prepare plates for contact with positive or negative film. |
| 17. | Unload exposed film from scanners, and place film in automatic processors to develop images. |
| 18. | Place masking paper on areas of plates not covered by positives or negatives, in order to prevent exposure. |
| 19. | Mount negatives and plates in cameras, set exposure controls, and expose plates to light through negatives in order to transfer images onto plates. |
| 20. | Operate and maintain a variety of cameras and equipment, such as process, line, halftone, and color separation cameras, enlargers, electronic scanners, and contact equipment. |
| 21. | Perform tests to determine lengths of exposures, by exposing plates, scanning line copy, and comparing exposures to tone range scales. |
| 22. | Mix solutions such as developing solutions and colored coating solutions. |
| 23. | Activate scanners to produce positive or negative films for the black-and-white, cyan, yellow, and magenta separations from each original copy. |
| 24. | Select proper types of plates according to press run lengths. |
| 25. | Reposition lamps and adjust aperture controls in order to provide high quality images. |
| 26. | Analyze originals to evaluate color density, gradation highlights, middle tones, and shadows, using densitometers and knowledge of light and color. |
| 27. | Set scanners to specific color densities, sizes, screen rulings, and exposure adjustments, using scanner keyboards or computers. |
| 28. | Perform minor deletions, additions, or corrections to completed plates, on or off printing presses, using tusche, printing ink, erasers, and needles. |
| 29. | Correct minor film mask defects with litho tape or opaquing fluid. |
| 30. | Position color transparencies, negatives, or reflection copies on scanning drums, and mount drums and heads on scanners. |
| 31. | Arrange and mount typeset material and illustrations into paste-ups for printing reproduction, based on artists' or editors' layouts. |
| 32. | Scale copy for reductions and enlargements, using proportion wheels. |
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