Enormous advances have been made in electronic prepress technology in recent years. However, electronic prepress technology carries a high initial investment (starting at around $30,000) for computer hardware and software, scanners and digital cameras. Employee training is usually necessary as well.
Offset lithographic prepress uses electronic computer-based systems to design the package, including all text, line work and continuous-tone images, and digital photographs. Text, graphics and the layout are created and edited with illustration design and imposition software. This reduces the quantity of film, developing chemicals and paper used, compared to traditional plate making. Only the final edited version is sent to digital output to the film used to make a printing plate or directly to the plate.
Film imagesetters for conventional analog proofs and plate making are eliminated by using digital proofing and digital plate making devices.
Electronic prepress systems were initially restricted to large printers because of the high initial equipment expenses. As the prices of computer hardware and software dropped, smaller printing operations have started to use them. Electronic prepress systems may reduce waste and improve productivity.
Best Management Practices & Pollution Prevention
Direct to Plate Prepress Technology
Another emerging (albeit expensive) technology is direct-to-plate, which enables the printer to image a computer-generated design directly to the plate. Digital plate quality often surpasses film-based technology because there is no image degradation from film contact with the plate. While this technology is not usually feasible for small printers, it is worth a brief discussion here because its acceptance and affordability will likely increase in the next few years. Direct-to-plate technology offers some of the following advantages:
- Reduced material costs by eliminating film and processing
- Prepress waste eliminated a reduction in paper waste and film and processing chemistry
- Short runs become cost-effective
- Decreased labor costs from stripping and platemaking since customers supply jobs on disks
- Reduced makeready times and reduced waste generation by eliminating defective plates caused by misregistration, dust, contact and vacuum problems
Digital proofing is also gaining acceptance among printers. While traditional proofs provide a very true look at film quality (revealing scratches and blemishes, for instance) and are particularly effective for fine printed works, they are labor intensive and use many expensive materials.
Digital proofs offer new ways to save time and money in the prepress stage. For short runs, where customers don't want to spend a lot of money on a proof, and for jobs that require potentially many changes or iterations, digital proofing is usually cost-effective. In addition, there is the opportunity for quick turnaround in remote proofing, since electronic files can be printed out at the customer's site.
Another steadily advancing technology is "soft proofing," the concept of proofing on the screen, with no hard proof. Soft proofs are more capable today of representing the true color of the final print job, and increasingly what you see on the screen really is what you get. Because proofs are expensive, many printers can work with customers to edit jobs on the screen, making necessary revisions before making a proof. Soft proofing can save printers money by reducing prepress waste and cutting labor costs.
For access to vendors who may supply alternative materials and equipment, see the PNEAC Vendor Directory.
Digital proofing systems still generate silver-laden wastes when processing the film to produce the printing plate.
The Clean Water Act strictly prohibits discharges of silver into publicly owned treatment works (POTWs) above certain levels. Generally all POTWs have established sewer codes, which specify acceptable levels of discharges including silver. Other pollutants of concern from film processors include pH, total suspended solids, and Biological Oxygen Demand (BOD) and/or Chemical Oxygen Demand (COD). All printers discharging to a POTW must obtain a copy of the local sewer code and meet its requirements for discharge limits, permits, and reporting.
In order to meet the local sewer discharge limits for silver, recovering silver from fixing baths is required and can be a money saving procedure. Many companies have found on-site recovery of spent fixer to be cost-effective, compared with the cost of disposal of the waste.
The type of silver recovery depends on the size of the facility, the type of film used, and the amount of silver-rich solution generated (volume of film processed) each day. The specific type of silver recovery will vary depending on the required silver recovery that is to be achieved.