Paper Training For Printers
Even in a world of increasingly more advanced technology, planning for trouble-free paper performance can still come down to the basics. Following a few rules of thumb for paper handling and usage can have a significant impact on a printed product's quality and efficiency of press operation.
1) Streamline workflow—One simple workflow rule to follow is FIFO (First In, First Out). The first paper coming into the warehouse should be the first to be printed, assuming it meets the job requirements. This will prevent paper from aging in the back of a warehouse because access is blocked by more recent paper shipments. Minimizing how long paper is warehoused helps ensure more uniform quality as materials go into production.
Efficient workflow strategies that examine and plan how paper moves in, out and around a commercial printing facility can protect paper to maximize print quality and improve runnability on-press. Paper company representatives may be able to provide expert consultation on warehouse design and workflow plans that will offer optimal paper storage and transport throughout an entire operation.
2) Protect paper during production—It is vital to store paper in its protective wrapping or covering throughout the entire job production process. For example, pallets of printed pages should not sit unprotected on a shop floor for hours before being processed through the bindery. Equally important, offset printed color shells and forms should not sit unprotected before being digitally personalized. Even covering work-in-process with a loose plastic sheet should suffice to protect it from dust and scuffs. If paper is left unprotected in a print production environment, even for brief periods of time, it is exposed to dust and moisture that can impact finished document quality.
Over longer periods of exposure, unprotected paper will equilibrate to the ambient conditions, so any extremes in environment should be avoided. High humidity, for instance, will cause paper to take on moisture and curl at the edges. Conversely, excess dryness will cause it to lose moisture and become brittle and tight at the edges. Either substrate condition can result in registration and wrinkling problems on an offset presses, or lead to image deletion on digital printers. To ensure optimal performance, paper should be stored under temperature- and humidity-controlled conditions that closely approximate the environment in which it will be utilized.
|Acclimation Times for Paper in Rolls|
|Difference in Warehouse and Pressroom Temperature:|
|Paper in Rolls|
|30˝ diam.||40˝ diam.||Length of time, in hours, paper should stand unopened:|
|15˝ wide||8˝ wide||5||9||12||15||18||25||35||54|
|30˝ wide||16˝ wide||8||14||18||22||27||38||51||78|
|60˝ wide||32˝ wide||11||18||23||28||35||48||67||100|
|Acclimation Times for Paper in Cases or on Skids|
|Difference in Warehouse and Pressroom Temperature:|
|Cubic Volume of Paper on Skid or in Cases||Length of time, in hours, paper should stand unopened:|
|6 Cubic Feet||5||9||12||15||18||25||35||54|
|12 Cubic Feet||8||14||18||22||27||38||51||78|
|24 Cubic Feet||11||18||23||28||35||48||67||100|
|48 Cubic Feet||14||19||26||32||38||54||75||109
|96 Cubic Feet||15||20||27||34||41||57||79||115|
3) Acclimate paper—If paper must be subjected to humidity and/or temperature changes, it should be allowed to acclimate to the new environment before processing. Acclimation time varies according to roll or case size and degree of change in temperature and/or humidity. (See charts)
Paper may endure severe temperature changes even in the short distance from an in-house warehouse to the printing floor. Acclimating paper after transport will result in optimal press performance and print quality.
4) Retain tracking information—Retaining proper identification with raw paper inventories and printed documents throughout the entire production process is essential. Commercial work can undergo many types of subsequent processing after the initial print run, including everything from forms conversion to digital printing. Therefore, it is critical that a substrate's identification information—such as product name, grade and lot number—be recorded on a ticket that is kept with the work throughout the entire production process. This will help with troubleshooting any problems that may crop up down the line. If given this information, paper mills can track problems and troubleshoot technical issues quickly and efficiently for the commercial printer and its customers.
5) Match the paper with the end-use application—A commercial printer that strictly does offset production may still need to consider the production requirements of other processes, such as digital printing. Many jobs—such as transactional statements, forms and newsletters—now leave an offset operation only to go right back into production in a digital department for customization and personalization. For these documents, it is necessary to use papers engineered for both digital and offset printing to ensure a high-quality end product. Considering the entire life of a document will help ensure selection of a paper that offers the best runnability and quality in all of the printing environments it will encounter.
If these few, simple precautions are taken in the selection, storage and in-process handling of paper, printers can go a long way toward ensuring trouble-free performance throughout the life of a document.
The above information was provided by Dennis Davey, a field technical service manager with Georgia-Pacific in Atlanta.