Choosing the Right Filtration for Large Format Digital Printers

Estimated reading time: 8 minutes

Needless to say that quality and consistency are paramount in our industry. This makes the selection of the appropriate filtration system critical. Proper filtration not only prevents contaminants from clogging printheads and degrading image quality but also reducing downtime and minimizing costly reprints.

As you might expect, it’s essential to replace periodically your filters to preserve optimum productivity. And that’s where the problem comes in. You remove the filter, check online and… you notice that most filters look pretty much the same. So you wonder, which filter do I need? Unfortunately, it’s not always that easy to identify the right model.

You must be aware that the filtration needs vary significantly depending mainly on the working environment and the type of ink used—whether solvent-based, aqueous, UV-curable, or latex—and understanding these differences is key to chose the right one.

But don’t worry we are here to help. Through this article we will provide guidance on choosing the correct filter for your printer based on your ink type and the types of contaminants that can affect large-format printing systems.

Why Filtration Matters ?

Filtration systems are typically installed between the ink supply and the printheads, ensuring clean ink flow and minimizing the risk of blockages. Ink impurities and particle contamination can quickly lead to nozzle clogs, inconsistent print quality, and increased wear on printheads. By implementing an effective filtration system, you can filter out unwanted particles, preserving the equipment’s functionality and reducing the likelihood of costly downtime.

Types of Contaminants in Digital Printing

The level of filtration required depends on the type of contaminants which has been in contact with the ink. Common contaminants include:

• Particulate Contaminants: Dust, fibers, and undissolved pigments are common particulate contaminants. These particles can come from the manufacturing environment or ink formulation itself and tend to block fine nozzles.
• Gels and Coagulated Inks: Some inks, especially those with pigment particles, can form gels or coagulated clumps that clog the printhead. This is often due to instability in the ink chemistry or exposure to certain environmental conditions.
• Microbial Growth: Certain inks, especially water-based and UV inks, are susceptible to microbial contamination. Microorganisms can multiply within the ink, producing organic debris that clogs nozzles or alters the ink’s physical properties.
• Chemical Precipitates: If the ink components are incompatible or exposed to fluctuating temperatures, chemical precipitates can form, which are challenging to remove without effective filtration.

Filtration Requirements by Ink Type

Each type of ink used in large-format digital printing has unique properties that dictate specific filtration needs.

Solvent-Based Inks

Solvent-based inks are known for their durability and resistance to fading. However, they can contain large pigment particles that require high-efficiency filtration, generally in the range of 5-10 microns. Technicians should look for filters that can withstand the aggressive nature of solvent inks without degrading over time.

Aqueous (Water-Based) Inks

Aqueous inks, often used for indoor applications, are sensitive to microbial contamination. Filters with smaller pore sizes, such as 1-5 microns, are recommended to remove biological contaminants effectively. Additionally, using biocidal additives in the ink can complement the filtration system, preventing bacterial growth.

UV-Curable Inks

UV-curable inks require filtration solutions that can handle thicker ink viscosities. Due to their formulation, these inks may contain photoinitiators and other chemical compounds that are prone to aggregation. Filters in the 5-20 micron range are suitable to prevent large particles from clogging the printheads.

Latex Inks

Latex inks are increasingly popular due to their eco-friendliness and flexibility across substrates. However, latex inks can be challenging to filter due to the nature of the resin particles. Using filters between 3-10 microns is generally effective.

Understanding Pall Filters : MAC, SCF, LCF, and FDM Explained

If you’ve ever come across terms like Multiple Application Capsule (MAC), Small Capsule Filter (SCF), and Last Chance Filter (LCF) and wondered how they differ, this post will break it down in simple terms.

Multiple Application Capsule (MAC): The Heavy-Duty Workhorse

The MAC filter is designed for versatility and heavy-duty use in printing processes. Think of it as the all-rounder that handles larger volumes of ink or fluid, ensuring that major contaminants are filtered out early in the process.

• Where it’s used: Early or intermediate stages of the printing process.
• Best for: High-volume operations and a broad range of ink types.
• Filtration level: Available in different levels, from coarse to fine filtration, depending on the specific printing needs.

Why it’s essential? By catching most of the impurities upfront, the MAC filter helps maintain the quality of your ink supply and reduces the load on downstream filters.

Small Capsule Filter (SCF): Compact and Precise

As the name suggests, the Small Capsule Filter (SCF) is compact and designed for precision. It’s the ideal choice for operations that require a more targeted and controlled filtration process.

• Where it’s used: Mid-stage filtration for specialty or small-scale printing applications.
• Best for: Precise ink formulations and when space is limited.
• Filtration level: Typically offers finer filtration than the MAC filter to maintain fluid consistency.

Why it’s essential? The SCF keeps your ink or fluid supply clean and consistent, which is particularly important in high-quality printing operations or specialty applications.

Last Chance Filter (LCF): The Final Guardian

The Last Chance Filter (LCF) is the ultimate protector in the filtration lineup. It’s installed right before the ink reaches the printhead, acting as a last defense against any remaining impurities. Within the Pall range, LCF filters are branded as Acro filters, purpose-built for inkjet printing applications. The series includes three models—Acro 25, Acro 37, and Acro 50—each designed to handle different flow rates.

• Where it’s used: Just before the ink enters the printhead.
• Best for: Protecting delicate printheads from clogs and damage.
• Filtration level: Ultra-fine to capture even the smallest contaminants.

Why it’s essential? Without the LCF, even tiny particles could clog your printhead, leading to costly downtime and inconsistent print quality. It’s a small but critical component that ensures smooth and

Filter Degas Modules (FDM): The Air Master

The Filter Degas Modules (FDM) are critical for preventing air bubbles in ink systems. Air bubbles can cause ink flow disruptions, lead to print defects, and even damage printheads over time. FDMs are designed to efficiently remove dissolved gases and bubbles from the ink before it reaches the printhead.

• Where it’s used: Installed before the printhead or in the ink supply line to remove air bubbles.
• Best for: Precision printing environments where consistent ink flow and superior print quality are essential.
• Filtration level: Focuses on degassing rather than particle filtration, ensuring a bubble-free ink supply.

Why it’s essential? Air bubbles, even tiny ones, can result in misfires and inconsistent print results. FDMs enhance printing performance by maintaining a stable, uninterrupted ink flow.

Conclusion: Finding the Right Filter for Your Needs

Printers operate with high precision, and even small contaminants can obstruct print nozzles or alter ink properties, resulting in defects in print quality and increased maintenance. Selecting the right filter is all about balancing key factors like ink type, contaminants, and operational requirements.

The type of contaminants present—whether pigment particles, dust, or chemical residues—dictates the filtration level needed.

Similarly, ink formulations (aqueous, solvent, or UV-curable) each have unique compatibility and flow demands. High flow rates require larger effective filter areas, while long-term durability depends on chemical resistance and robust pressure tolerance. Ensure that the filter’s efficiency is compatible with your ink. For instance, a filter with too fine a pore size might restrict ink flow, while one that is too coarse won’t capture enough contaminants.

Last but not least, take consideration of your operational requirements. High dirt-holding capacity is beneficial for long print runs and reduces the need for frequent filter changes. In addition, the type and orientation of the connections should facilitate quick filter changes with minimal mess.

By aligning your filter selection with these factors, you can maintain optimal performance and extend the life of your printing equipment, delivering consistent, high-quality results with every project.

Got any questions about optimizing your printer’s filtration system? Share them in the comments—we’d love to help!

Note from the author: For the sake of simplicity we primarily referenced Pall filters due to their established reputation for reliability in industrial environments and their extensive presence in the printing industry. That being said, other manufacturers, such as Porvair and 3M, also offer high-quality alternatives, demonstrating the importance of exploring diverse options to find the solution that best matches specific printing needs and operational conditions.