In the packaging industry, the expiry of inks plays a crucial role in maintaining product quality, reducing waste, and ensuring compliance with safety regulations. Whether it’s solvent-based, water-based or UV-curing inks, each type has its own shelf life, determined by factors like pigment stability and storage conditions.
Once opened, the ink’s life can shorten, and its performance can be affected by exposure to air and contaminants. Managing ink expiry dates is therefore vital for achieving consistent results and avoiding potential issues, especially when working with inks that will be used for food packaging.
In this blog, we’ll explore how tracking ink expiry dates and using software tools like GSE Traceability can improve your processes. For example, you can update the expiry date of opened containers and, more importantly, track the closest expiration date whenever base or leftover inks are mixed to create a new spot colour. Let’s explore how proactive ink expiry management can benefit your business and avoid costly mistakes.
Shelf life of packaging inks
All materials age over time, and many polymers, like coatings and inks, undergo changes in their properties. Shelf life as labelled on a new ink container refers to the duration during which a material remains suitable for its intended use. This term is also defined by the specific requirements that the material must meet. Printers expect consistent, reproducible results from a given type of ink, which is only feasible if all other conditions – such as the substrate and printing equipment settings – remain constant.
The shelf life is determined by factors like pigment stability, and potential chemical degradation over time. Proper storage is therefore crucial. Inks should be stored in a dry and stable environment, away from direct sunlight, and at an appropriate temperature, avoiding extremes such as freezing or excessive heat.
The shelf life of packaging inks under these conditions is typically between 12 to 24 months from the date of manufacture, but it can vary depending on the ink type and brand. In general, solvent-based inks, for example, have a longer shelf life than UV-curing inks.
Expiration date after opening an ink container
Once a container is opened, the ink is exposed to air and potential contaminants, which can cause the ink to dry out, thicken, or degrade. It is therefore important to always tightly seal the container after each use.
Your ink supplier can provide information on how long an ink can be stored after the container is first opened, which is typically between 6 and 12 months.
Pot life: expiration dates after mixing base components and reusing return inks
Spot colours can either be purchased ready-mixed or created by combining base colors and varnishes according to a formula. When mixed manually or automatically, the ingredient with the earliest expiration date dictates the “pot life” of the final mixture.
If return inks are used alongside fresh base inks to mix a spot color, the pot life date of the return ink container must be considered when determining the pot life of the newly mixed batch.
Recording shelf life and expiry dates to calculate pot life dates
Without proper software, it is nearly impossible to keep track of these expiry dates and use the inks before they expire. For this reason, we integrated this functionality into our software.
With GSE Traceability, you can log the shelf life of new containers with base components in the database, optionally by scanning the label.
Once a container is opened, you can update the expiry date if the time remaining after opening is shorter than the original shelf life. After saving this update, the date can no longer be modified.
When mixing various ingredients, the software automatically identifies the earliest expiry date and records it as the pot life in the database. The optional GSE Return ink management software also considers the expiry dates of returned ink ingredients. Using this software therefore makes it possible to know if the return inks determine the pot life.
Various software functions and labels help you to use inks before they expire
GSE software provides various screens and grids where expiry dates are displayed, like in machine stock, inventory barrels, return inks and dispense history. If the ink has expired, it is highlighted in orange for easy identification.
Grid functions, such as sorting or filtering inks by expiry dates, help prioritize and ensure inks are used before they reach their expiry.
When registering inks with GSE Advanced logistics, the expiry date can be scanned or manually entered and then printed on the inventory barrel label.
When a new barrel is connected to the dispensing system or used for filling, the expiry date can be entered manually or transferred from the previously described inventory barrel and printed on the fill/exchange label. If ink leftovers are transferred from the previously connected barrel, the expiry date of the previous barrel can also be printed on the label!
After dispensing, a label can be printed with the expiry date to indicate the pot life.
When inks are weighed upon return from the press, a return label with the expiry date can be printed after weighing. If the ink has expired, a pop-up warning will appear on your screen, notifying you of the expired ink and prompting you to decide whether to proceed.
Our standard traceability reports also display the expiry date of the selected container (i.e., the pot life date), as well as the container dispensing date, ensuring it can be demonstrated that no expired inks were used on the production day.
Working life of inks vs. risks of using expired products
Obviously, inks can still work after the expiry date has passed. For example, there are cases where an ink supplier has checked 20-year-old solvent-based inks in unopened cans, and after thorough stirring, the inks were still usable. However, ink suppliers do not recommend using inks past their expiration date. Printers who choose to use such inks do so at their own risk, without any manufacturer liability. Additionally, older inks may contain substances that are no longer permitted under recent regulations. In contrast, newly manufactured inks will always comply with current standards and regulations. Additionally, using expired inks in packaging materials – especially those in contact with food – raises significant concerns regarding food safety and regulatory compliance.
The importance of proactive ink expiry management
Effectively managing ink expiry dates is essential for achieving consistent print quality, reducing waste, and maintaining compliance with industry and food safety standards. While some inks may remain functional beyond their expiration date, relying on such practices introduces risks, including potential performance degradation, regulatory violations, and food safety concerns.
By leveraging tools like GSE Traceability, GSE Return ink management and GSE Advanced logistics software, you can streamline expiry management processes, ensuring inks are used efficiently and at their optimal quality. Automated tracking of expiry dates, combined with features like pop-up warnings, sorting and label printing, empowers you to make informed decisions about ink usage.
Taking a proactive approach to ink expiry management not only helps you avoid costly mistakes and unnecessary waste, but also supports sustainable practices and compliance with current regulations. By focusing on ink quality and safety, you can deliver superior results while reinforcing your commitment to environmental responsibility and regulatory adherence.
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