Though most of us understand the need to run a characterization to fingerprint our processes, many can improve on what information should be recorded about the characterization and how the information is interpreted.
When a press characterization is run, it is important that certain information is recorded and retained for future reference. This information is not only important to the printer but to the pre-press separator as well. Note, a characterization is meant to fingerprint a specific printing process. This process includes variables such as the substrate, plate, type of plate exposure, stickyback, anilox line count(s), ink set, and press. If any of these variables should change, then the printing process would be different and therefore require a different characterization. Though the new characterization may show that there is little change, it is important to find that out before major decisions are made to change any one of these variables permanently. Following is a list of specific items that should be recorded in order to validate and qualify how the characterization was run.
Date - This is critical information, as it will help to develop a history of a specific printing process. This history will help to visualize the progress or regression of that specific printing process.
Press - This is information that helps identify how a press prints. It is important to run a characterization for each press, for it may help to identify similarities in dot gain between certain presses. Thus allowing jobs to run on more than one press. It will also help to identify what issues may arise when moving a print job to a different press.
Initials - The initials of the main operator is valuable in understanding how each individual affects the printing process. Unfortunately this is a variable for which we cannot really compensate.
Web Speed - When running the characterization it is important to run at the normal production speed for that printing process. Running the press slower or faster will affect the print thus tainting the information gathered from the characterization.
Substrate - The substrate can drastically alter the print results. Though the visual differences between uncoated and coated paper or paper and film are much more obvious, there can be differences between two coated or two film substrates.
Ink Set - The set of inks used is another critical variable. Even the slightest changes can make major differences at press.
Plate Type - Plates have many variables that affect how line art, screen art, and process art print. Durometer, relief, and thickness are three major factors that impact the print. It is therefore important to give both the plate description (and manufacturer) as well as the plate thickness.
Plate Exposure - It seems there are ever expanding ways to expose a plate. Three exposures common to today include: conventional, point light source, and digital exposures. All of which affect the final print.
Stickyback - Like plates, stickyback has many variables that affect how line art, screen art, and process art print. Durometer/compression and thickness are primary factors that impact the print. It is therefore important to give both the stickyback description (and manufacturer) as well as the stickyback thickness.
Anilox Configuration - As with inks, substrates, plates, plate exposures, and stickyback, the anilox is another critical variable to track. Though all of these variables should be recorded for each color run in the characterization, usually the anilox is the only one that varies much from deck to deck. Include both the line count and cell volume when recording the anilox configuration for each color.
Ink Viscosity - The viscosity for each ink should be checked while the press is at optimum speed and good print samples are being run. If the viscosities are not where they should be, then no print samples should be pulled until the viscosities are in check. Ink pH and ink temperature are also valuable information to record.