Filter Cloths 101 & FAQ

M.W. Watermark™ manufactures all of our filter cloths in our facility in Holland, Michigan, U.S.A.

By manufacturing cloths in-house, we are able to utilize our laser-cutting tables and experienced sewing staff to provide fast turnaround times and ship direct – all while maintaining a quality product and the best service for our customers.

Watch the videos below to learn more about our filter cloth manufacturing processes. (Scroll to bottom of page for “how-to” videos on cloth installation).



The Role of Filter Cloths and Cake

It can be easy to look past the cloth’s true role in a process, believing that the cloth does the filtering, when in reality most of the filtering gets done by the cake itself forming in the recessed chamber. Understanding this, it becomes easier to improve the press operation and to adjust to problems and changes.

Filter cloths are the front line of a filtering process, serving as the the foundation needed to build a filter cake.

M.W. Watermark Filter Cloth 101: Filter Press Cake
Filter Press Cake
Learn More on Our Blog…

“How to Order the Right Size Filter Cloths to Fit Your Filter Press” – Read more.

“Filter Presses and Cloths for Lees Filtration” – Read more.

“Filter Press Maintenance and Critical Spare Parts” – Read more.

“How to Maximize the Life of Your Filter Cloths”Read more.

“M.W. Watermark Offers a Full Range of Laboratory Services” – Read more.

“Filter Cloths for Large Filter Presses: Mining and Energy Industry Spotlight”Read more.

“Precoat: What It Is and How to Apply in a Filter Press”Read more.

“A Filter Press Is a Depth Filter: The Role of Filter Cloths and Cake in the Dewatering Process”Read more

“How Filter Cloth Media Selection Affects Performance”Read more.

“How to Know When to Replace Your Filter Cloths”Read more.

“Options for Cleaning Your Filter Cloths”Read more.

M.W. Watermark is a filter cloth manufacturer in Holland, Michigan, USA

Filter Cloth 101: Terms

Cloth Blinding

When a cloth’s porosity is hindered, and the cloth no longer allows the filtrate to flow.

Monofilament Cloth

These fibers are single, smooth, rounded extrusions. “Mono” cloths have excellent cake release characteristics and resistance to blinding. This style has low particle retention. To provide a layman’s visual, this material is very similar to fishing line. These cloths have the advantage of being more permeable, allowing for higher flow rates.

Monofilament fabric also has advantages in cleaning, which can help deter microbiological contamination in food and beverage applications.

The only drawback to monofilament cloths is in their durability. Because these cloths are woven from individual strands instead of multiple fibers woven together they are more fragile, and a crack in a single strand can compromise the stability of the entire cloth.

M.W. Watermark Monofilament Filter Press Cloth
Click Image to Enlarge
Multifilament or “Spun” Fibers

Compared to the “mono” fiber above being similar to fishing line, with “multifilament” threads, think “yarn.” The fibers vary in size, but are grouped together in a single strand. Multifilament fibers feature good particle retention and are very durable, since a break in a single thread has very little impact on the overall stability of the cloth.

M.W. Watermark Multifilament Filter Press Cloth
Click Image to Enlarge
Mono-Multi Cloth

Mono-Multifilament fabrics have become very popular, as they combine the benefits of both “mono” and “multi” to get the best of both worlds. That is, the excellent cake release, higher flow rates and ease of cleaning of monofilament, plus the durability of multifilament fibers.

Because of these combined characteristics, mono-multi filter cloth has been found to be ideal for “lees filtration,” a solid-liquid separation process used in winemaking.

M.W. Watermark Mono-Multi Filter Press Cloth
Click Image to Enlarge
CGR vs. NG

“CGR” is an acronym for “Caulked, Gasketed, Recessed chamber.” CGR plates should provide a virtually leak-proof filter press. Cloths for these plates are octagon shaped, with a caulking rope or cord sewn into the edge of the cloth. “NG” means “Non-Gasketed.” The NG cloth is faster and simpler to install, though the trade off is that occasionally some dripping can happen when using NG cloths.

M.W. Watermark CGR Filter Press Cloth Installed in a Filter Plate

CGR Cloth Installed in a Filter Plate
NG Cloth

NG Cloth Installed in a Filter Plate
M.W. Watermark CGR Filter Cloths

CGR Cloths
M.W. Watermark NG Filter Cloths

NG Cloths (with Latex Edging)
Latex Edging

A latex coating can be added to the edges of an NG cloth to help prevent leaks.

M.W. Watermark Filter Cloths - Latex Edging

CFM

“Cubic Feet per Minute” is the measure of flow or air permeability of the cloth media.

Warp and Weft

Warp is the threads that run lengthwise in a cloth. Weft is the threads that run across the width of a cloth at right angles to the warp. These are also known as filling threads. Warp should run vertically when installed.

Weave Pattern

The most common are plain, twill, and satin (or sateen).

  • Plain Weave is average in strength, cake release, and stability.

M.W. Watermark Filter Cloths - Plain Weave

  • Twill Weave adds a diagonal rib or line to the weave, adding strength at the expense of a little stability. Cake release is average.

M.W. Watermark Filter Cloths - Twill Weave

  • Satin Weave is popular for its excellent cake release and excellent resistance to blinding.

M.W. Watermark Filter Cloths - Satin Weave

Filter Cloth Materials

Filter cloths come in many different materials including polypropylene, polyester, cotton, nylon, felt, and many other materials. The most common filter material:

  • Polypropylene: Polypropylene is the most common material. It has strong resistance to acid and alkali alike. A satin finish added to the fiber can allow for easy cake release. “PP” is a top choice for a wide range of applications, and is by far the most popular material. Latex borders can be applied to a non-gasketed cloth to provide a better seal under pressure.
M.W. Watermark Polypropylene Filter Cloth
Click Image to Enlarge
  • Nylon: This durable fiber is often chosen for its long life in the face of abrasives. Though higher in cost, nylon blends offer such durability that the higher cost can be justified by longer service life.
M.W. Watermark Nylon Filter Cloth
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  • Polyester: Often chosen when sustained operating temperatures are over 180 degrees, or when oxidizing agents are present.
M.W. Watermark Polyester Filter Cloth
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Filter Press Cloth FAQ

Q: What is the micron rating of this cloth?

A: Cloth does not have a micron rating. Cloth air permeability, or porosity, is measured using the Frazier Air Permeability scale. The unit of measure is cubic foot per minute, or CFM, which is a cloth permeability measurement. The ranges of CFM are wide, and are determined by the thread counts and weight of a fabric.

Q: How can I make the installation of gasketed cloths faster?

A: Depending on your press operation, changing cloths can be labor intensive and difficult, and often the down-time is problematic. One solution is to purchase a cloth air hammer (P/N 4000-0235, $258.00 ea) which greatly speeds the filter cloth installation.

Another solution is to get additional plates to “swap out” between cycles, so you can replace cloths in the extra plates while the press still runs at full capacity.

A third solution is to send plates with old cloths to M.W. Watermark, and have our experienced staff clean the plates, change the cloths & gaskets, and ship them back. Usually this service can be done within 2-3 days in our facility.

Q: My cloths are wearing out at the center feed neck/corner feed. What can I do?

A: You can ask for either a latex reinforced cloth, a latex reinforced cloth barrel neck, or extreme cases a rubber barrel neck – to protect against wear in those areas.

M.W. Watermark Latex Reinforced NG Filter Cloth
Latex Reinforced NG Filter Cloth
M.W. Watermark - Rubber Barrel Neck Filter Cloth
Rubber Barrel Neck
M.W. Watermark Latex Reinforced Cloth Barrel Neck Filter Cloth
Latex Reinforced Cloth Barrel Neck
Q: How can you test a new cloth for our application?

A: First, contact our process experts for a recommendation. We may recommend Air Permeability Testing or other Laboratory Services. Once a cloth type is selected, we recommend that you run a test on a shortened stack in your press. This can be done by moving the “end plate” to cut off the stack so that just the test cloths are used. To protect the plate at the end of the stack, use a back-up plate to support the tail plate. Take care to monitor the pressure, as it will fill fast, and run the press with the shortened stack. You should see results quickly.

Q: Can I clean the cloths with a pressure sprayer?

A: You can, if care is taken to not get too close with the spray tip, or use the sprayer in anything other than a “fan” spray pattern. Keeping spray pressure under 1000 PSI is recommended as well.

Q: Can we clean cloths with chemical cleaners?

A: Polypropylene cloths can handle both caustic and acidic solutions. Nylon, polyester and felt cloths need special consideration and may be damaged from these chemicals. Contact M.W. Watermark about your specific situation.

Q: How can I extend my filter cloth life?

A: Filter cloth life is shortened by chemicals, mechanical wear, abrasion, and blinding. We can help to determine whether your cloths are being attacked by your process chemicals. Mechanical wear can be reduced by using a more durable cloth. Blinding often comes from “slamming” sludge into the press. Consider an Auto Feed Pump Control System, or an AFPCS to automatically and gradually increase pressures. “Pre-coating” a press with DE or similar products can also add substantial life to cloths. The coating protects against wear and minimizes blinding.

M.W. Watermark offers:

  • Gasketed (CGR) and non-gasketed (NG) cloths
  • Hook-and-loop material and latex additions to improve sealing on non-gasketed cloths
  • Custom patterns and styles
  • Fast lead times: Many standard cloths are stocked for quick shipping
  • Filter cloth removal and installation

Visit our Filter Cloths main webpage to learn more and download our Filter Cloths Product Guide.

Filter Cloth Installation, Accessories and Other Tools

Need accessories for your filter press, including spatulas, cloth installation tools or bulk bags? Download our Aftermarket Accessories Sheet.

M.W. Watermark now offers a complete tool kit for installing and servicing gasketed filter plates and cloths. Download our CGR Filter Press Service Took Kit Brochure.

M.W. Watermark CGR Filter Press Service Took Kit (40033019) - Updated September 2018

Filter Cloth Installation and Service Videos

How to Install a CGR Filter Cloth

How to Install a Head Cloth

How to Install a Non-Gasketed (NG) Filter Cloth