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Final Filtration to Protect Ink Quality

Final product quality depends on the quality of the final filtration step. This most critical filtration process can prevent particles and other contaminants from adversely affecting the ink. Continue to read below for more details on final filtration of ink jet ink, or go to the product selection table at the bottom of this page to explore specific filter options.

The amount of particle reduction and what needs to be removed can vary widely. Pigment based inks will often only need larger particles removed and the remaining particles evenly disbursed in the liquid. For some dye based inks, removing undissolved particles and maybe even bacteria is called for.

The housings marked “3” in the schematic are where “final” filtration is performed. This is just before packaging and is shown as a multiple step filtration process. It is possible to perform final filtration with a single step, but the success of the process depends on the type and number of particles in the stream and the size distribution of those particles. If the goal is removal of either bacteria or very small, sub-micron sized particles, operators will often use 2 or more stages of filtration. Using multiple filter steps most often improves filtration process efficiency and cost-effectiveness. Critical Process Filtration offers services that can help you design your filtration process.

Common Filtration Steps in Ink Jet Ink Formulation
Particle Filtration in Reprocessing

Custom systems are designed for new applications and to solve challenges in existing processes. Critical Process Filtration will work with you to design, build and install a cost-effective system that delivers the results you need. Contact us or visit our custom filtration systems page for more information.

Application Summary

For more information on this specific application, click on the link below to download an Application Summary.

Choosing the Right Filters

With such a wide range of possible filtration goals, the full range of filter technologies available may be used as a final filter. If the goal is removal of visible particles, which generally means removing particles larger than 20 microns, depth filters are used. These could be relatively inexpensive, standard depth filters with thick media that capture particles in the depth of the media. If the particle load is high, then more expensive pleated depth media filters may be used. Pleated filters have a large surface area that will hold a much larger amount of particulate.

If removing smaller particles, those larger than about 1 micron in size, is the goal, then depth filters may still be used, but with the target particle size smaller, this level of filtration is often done using pleated depth media filters, though membrane filters may be used for a few applications.

Membrane filters are used to remove bacteria and sub-micron size particles. Pleated membrane filters are the most efficient at removing these size particles, but are almost always used in a multi-step filtration process with prefilters protecting the membrane filters.

The filters chosen must, obviously, be compatible with the product and remove the target contaminants. They cannot adversely affect the final product. With multiple filter media materials and filter device types, Critical Process Filtration can help you find the compatible filtration solution that will protect your product and your customers’ printing results.

The table below shows the filter media in cartridge, capsule and disc filter configurations. We also have housings for filter cartridges. Click on the PDF Files in the appropriate location to download a data sheet for the filter media and configuration that fits your needs. Critical Process Filtration also has specialty filter devices that may fit your application.

Media Code
Filter Media
Filter Grade
Cartridge Data Sheet
Capsule Data Sheet
Disc Filter Data Sheet
Pore Sizes Avail. (µm)
Melt-Blown Polypropylene Media
1, 3, 5, 10, 20, 30, 50, 75, 100
Continuously spun bonded polypropylene media for consistent 85% nominal performance
Nano-spun Polypropylene Media
1, 3, 5, 7, 10, 20, 30, 40, 50
Very high retention efficiency (99%) and high load capacity to protect downstream processes
Pleated Polypropylene Depth Media
0.1, 0.22, 0.45, 0.65, 1.0, 3.0, 5.0, 10, 20, 30, 40, 60, 100
100% polypropylene construction for high purity
Melt-Blown Nylon Media
1, 3, 5, 10, 20, 30, 50, 75, 100
Spun bonded for consistency with broad chemical compatibility
Pleated Fiberglass Depth Media
0.22, 0.30, 0.45, 0.65, 1.0, 2.0, 3.0, 5.0, 10, 20, 30
High capacity filters for clarification and prefiltration applications
Asymmetric Polyethersulfone (PES) Membrane
0.03. 0.1, 0.22, 0.45, 0.65, 1.8, 1.0, 1.2
Highly asymmetric, hydrophilic PES membrane in single-layer configurations for high efficiency, high flow rates
Symmetric Polyethersulfone (PES) Membrane
0.03. 0.1, 0.22, 0.45, 0.65, 1.8, 1.0, 1.2
Symmetric, hydrophilic PES membrane for high efficiency filtration of water.
Nylon 6,6 Membrane
0.1, 0.22, 0.45, 0.65
For removal of small particles and microorganisms in a wide range of chemicals.
High Capacity Polyethersulfone (PES) Membrane
0.2, 0.5 and 1.0 single layer; 0.5/0.2 and 1.0/0.5 dual layer
High void volume membrane for small particle or bacteria reduction.
High Capacity, Hydrophilic Polyvinylidene fluoride (PVDF) Membrane
0.22, 0.45, 0.65, 1.2
High void volume membrane with high holding capacity for systems that may have high particulate loads.
Polypropylene General Service Grade
0.1, 0.22
Hydrophobic membrane for non-aqueous liquids and gases with excellent material compatibility and low extractables
Polyvinylidene fluoride
(Hydrophobic PVDF)
0.22, 0.45, 0.65, 0.85, 1.0
High capacity, hydrophobic membrane for long life in air and process gas filtration.
PTFE General Service Grade
0.1, 0.22, 0.45, 1.0, 3.0
Highly hydrophobic. Superior air filtration flow rates for tank vent applications

To estimate the number of filters you will need for your application, use our unique sizing tools.

Contact Critical Process Filtration if you have any questions, wish to discuss a specific application or want to learn more about any of our Products and Services. We look forward to hearing from you!