Plugged Anilox Roll Cells
Improperly managed ink viscosity could result in print related problems such as deformed dots, dirty print or color variances. Inks that are not thoroughly mixed and homogeneous can trap solids in the anilox cell, creating print imperfections as well as cleaning difficulties. This problem is especially true with water based inks that do not rewet and become soluble.
Additionally, ink viscosity directly affects the transfer from anilox roll to plate. This changes the volume of ink applied to the substrate and therefore the color and intensity of the image. This is the reason many printers use different anilox rolls at different times of the day or year.
Job Rejections Due to Print Related Issues
For many companies, branding is one of their most important marketing tools. In many cases, the color of the packaging is more important than the brand name on it.
Ink formulations are as important to printing as recipes are to cooking: A wrong ingredient added, or over or undercooking a dish can turn an evening of fine dining into a gastronomical nightmare. The same holds for inks.
Anything associated with a company’s brand comes under greater scrutiny and expectations for a higher quality print job become the norm. If the color associated with the brand is not absolutely correct or if there are any print related imperfections, there is a higher chance for a job to be rejected. Often, these rejections, or customer returns, can be traced back to inconsistent ink viscosity.
Ramifications of job rejections are many. Potential for thousands of dollars in lost revenue due to production downtime, manpower needed to set up and rerun the job, additional film, additional ink and additional press time all seriously affect the bottom line.
Excessive Cleanup Due to Ink Related Issues
If you have housekeeping issues around the ink pail and throughout the press, you may have a viscosity related problem. Ink management, including viscosity control as well as correct ink mixing, can aid in ensuring fewer issues with, among other problems, slinging or buildup.
Commonly, this “slinging” results in longer, more extensive cleaning time due to the thin ink being thrown or spilling throughout the harder to reach areas of the press during a run.
The other side is cleaning problems due to high viscosity inks, which can build up and take more time to remove. Both of these issues require time, manpower and resources to ensure they are resolved.
Press Stoppage to Address Cleaning Related Issues
Proper ink viscosity management can reduce the number of times it is necessary to stop a press during a run to clean plates, rolls or other areas due to ink buildup or slinging.
As viscosity begins to drift out of range and affect the quality of the finished product, it may require more than adjusting the viscosity, impression and other quick fixes. It may involve a complete cleaning of the deck(s) responsible. Once it’s apparent the usual tricks won’t work, it’s back to lost time, lost production and lost resources. Margins, which are already tight, begin to shrink even more.
Adhesion/Flaking Issues
When manually maintaining ink viscosity, there is a risk of adding too much or too little solvent to bring it back into spec. In many cases, the operator relies on his/her experience in “knowing” the viscosity is out of range and how much solvent to add to bring it back into spec. This haphazard approach is very inefficient, and can result in large swings in viscosity and cause a high use of solvent per job. Further, if different solvent blends are used for different inks, the chance for adding the wrong one exists, which can result in contaminating the ink and causing additional problems, such as adhering, peeling or flaking.
Inks Not Drying/Drying Too Quickly
When manually measuring and controlling ink viscosity, there is always the possibility the ink to solvent ratio may not be correct for the volume applied. This can result in the ink drying either too quickly or not quickly enough. Variation in ink drying time can lead to a variety of print related issues including inconsistent color, bleeding, smearing and flaking. Each of these may cost valuable time, labor and lost income due to rejections. A common thread running through all of these issues is the potential costs applied when the print job is not monitored from start to finish. Although not the only critical process to affect the final product, ink viscosity is one of the most crucial elements of any printing process. If you are experiencing any of these symptoms, ink viscosity may be the first and easiest place to start your investigation.
About the Author: James Dulong has been involved with process viscosity control for more than 17 years. As technical sales manager of Norcross Viscosity Controls, James is responsible for working directly with many companies in a variety of industries to implement process improvement systems that measure and control the viscosity, pH and temperature of their fluids.
Additionally, James also oversees a global network of highly trained sales agents and representatives, ensuring customers receive the solutions they need, and the personal attention and support they require. In his (limited) spare time, James enjoys golfing and traveling with Patty, his wife of 38 years, as well as squeezing in some guitar playing and running.