What Does a Forming Fabric Cleaner Remove?

A forming fabric cleaner removes fibers, fines, fillers, pitch, stickies, chemical deposits, dirt, and other contaminants that accumulate on the surface and inside the openings of a paper machine forming fabric. These deposits restrict drainage, change water flow through the fabric, reduce permeability, and can eventually affect sheet formation, moisture profile, machine speed, and fabric service life.

Cleaning is therefore not simply a cosmetic process. The forming fabric is the first major piece of paper machine clothing to contact stock from the headbox, and its open structure must remain sufficiently clean for water to pass through while fibers are retained on the surface. Sun Hong Group supplies Spray Shower System equipment and related cleaning components for continuous paper-machine clothing maintenance. The correct cleaner should remove contamination effectively without damaging yarns, changing fabric structure, or wasting excessive water.

Why Does a Forming Fabric Need Cleaning?

A forming fabric performs three jobs at the same time: it supports the fiber suspension delivered by the headbox, allows a large amount of process water to drain through its structure, and carries the newly formed wet sheet toward the press section. Sun Hong's Forming Fabric range includes single-, double-, 2.5-layer, and triple-layer constructions designed for different paper grades and machine conditions.

During operation, the fabric continuously contacts fibers, fines, fillers, process chemicals, dissolved and colloidal substances, and contaminants that escaped stock preparation. A portion of this material can remain attached to yarn surfaces or become lodged within the fabric voids. As deposits accumulate, the effective open area becomes smaller and water cannot pass through the fabric as uniformly as it did when the clothing was clean.

The contamination process is gradual. A mill may first notice slightly poorer drainage or higher vacuum demand rather than obvious visible dirt. Over time, the machine may require more vacuum to remove the same amount of water, wet-line position may change, moisture profiles may become less uniform, and the forming fabric may become more difficult to clean during normal operation.

A forming fabric cleaner is designed to interrupt this buildup before contamination becomes severe. It uses controlled water jets, spray showers, oscillating cleaning pipes, or other mechanical and sometimes chemical cleaning methods to remove deposits while the machine is running or during scheduled shutdowns.

What Contaminants Does a Forming Fabric Cleaner Remove?

The exact contamination depends on raw material, paper grade, additives, recycled-fiber content, water quality, machine chemistry, and stock-preparation efficiency. A recycled linerboard machine may have very different deposits from a fine-paper or tissue machine.

The most common contaminants include:

A cleaning system may remove several types simultaneously, but no single cleaning method is equally effective against every contaminant. Loose fibers can often be removed readily with high-pressure water, while hardened mineral scale or aged pitch may require a more specialized chemical or shutdown-cleaning procedure.

How Do Fibers and Fines Block a Forming Fabric?

Fibers are the material the forming fabric is designed to support, so some interaction with the fabric surface is unavoidable. Most usable fibers remain in the sheet, but individual fibers and fiber fragments can become caught around yarn intersections or pushed into open voids by drainage forces.

Fines are particularly important because they are much smaller than normal fibers. They can move deeper into the fabric structure, especially in multilayer fabrics where internal void volume is greater. Once retained inside the fabric, fines can combine with fillers and sticky substances to create deposits that are more difficult to remove than loose surface fibers.

If these deposits accumulate, the forming fabric becomes less permeable. Water then seeks alternative drainage paths, which can create local differences in drainage rate. The sheet may form differently across dirty and clean areas, contributing to non-uniform moisture or formation.

A high-pressure cleaner helps by directing concentrated water energy into the fabric openings and dislodging fibers that normal process water cannot remove. The cleaning jet must reach the contaminated area without creating enough impact to damage polyester yarns or disturb seams and edges.

Cleaning should therefore begin before plugging becomes severe. Once deposits are compacted deep inside the structure, normal online washing becomes less effective and more aggressive shutdown cleaning may be required.

How Are Fillers Removed From Forming Fabrics?

Modern paper grades often contain mineral fillers such as calcium carbonate, clay, or titanium dioxide. These particles improve properties such as opacity, brightness, smoothness, printability, or cost structure, but fine mineral particles can also accumulate in paper machine clothing.

Fillers do not usually create one large visible deposit immediately. Instead, small particles can settle within fabric voids or adhere to other organic deposits. A layer containing fines, filler, pitch, and chemical residue can gradually become dense and difficult for water to penetrate.

High-pressure water can remove loosely attached mineral material and help prevent progressive filling of the fabric structure. The cleaning system should provide sufficient impact across the full fabric width rather than cleaning only isolated tracks.

Water quality also matters. If cleaning water itself contains suspended solids, nozzle passages may block and additional particles may be introduced to the fabric. Filtration upstream of high-pressure showers is therefore important for both nozzle reliability and cleaning consistency.

When deposits have already hardened through interaction with process chemistry, water alone may not fully restore permeability. Chemical cleaning during planned downtime can sometimes be required, but chemical type should be selected according to both the deposit and fabric material.

How Do Pitch and Stickies Affect Forming Fabric Cleanliness?

Pitch and stickies are among the more difficult contaminants because they can behave as adhesives rather than simple solid particles.

Pitch originates mainly from natural wood extractives and resinous materials. Stickies are especially common in recycled-paper systems and may come from pressure-sensitive adhesives, labels, tapes, hot-melt materials, coatings, inks, and other recovered-paper contaminants. These substances can remain dispersed in stock before depositing on machine surfaces.

Once a sticky deposit forms on a forming fabric, it acts as a collection point. Fibers, fines, fillers, dirt, and other particles adhere to the tacky surface, causing the deposit to grow. The result can be a combination of organic and inorganic material rather than one pure contaminant.

High-pressure water can remove fresh or weakly bonded deposits and prevent buildup, but aged or chemically resistant stickies may not respond completely to mechanical washing. Mills may need to control the problem earlier through furnish management, stock preparation, chemical programs, temperature control, and scheduled chemical cleaning.

This is where upstream equipment becomes important. A correctly selected pressure screen can remove many larger shives, plastics, fiber bundles, and deformable contaminants before stock reaches the paper machine. Pressure screening cannot eliminate every dissolved or colloidal contaminant, but effective stock preparation reduces the contamination load arriving at the forming section.

A forming fabric cleaner should therefore be regarded as the final online maintenance layer, not the only contamination-control system in the mill.

Can a Forming Fabric Cleaner Remove Chemical Deposits?

Yes, but effectiveness depends on the type and age of the deposit.

Papermaking systems contain retention aids, sizing chemicals, strength additives, coating residues, defoamers, biocides, fillers, and other process chemicals. Under certain operating conditions, these materials can interact with fibers and minerals to create deposits on the fabric.

Fresh, weakly attached material may be removed with water jets. Harder organic films or mineral scale can be more resistant. If deposits have chemically bonded or hardened onto the yarn surface, increasing water pressure continuously may not be the best solution because excessive pressure can damage the fabric while leaving the chemical deposit only partly removed.

A better cleaning strategy distinguishes between:

Online Mechanical Cleaning – Used continuously or frequently to prevent routine contamination from accumulating.

Intermittent High-Pressure Cleaning – Used when stronger mechanical removal is required.

Shutdown Chemical Cleaning – Used for deposits that cannot be removed effectively with water alone.

The chemical cleaner must be compatible with the forming fabric material and the specific deposit. Strong chemicals used without understanding the contamination can attack yarns, seams, coatings, machine parts, or wastewater systems.

How Does a Forming Fabric Cleaner Remove Slime and Biological Deposits?

Paper machine white-water systems contain moisture, nutrients, fibers, heat, and large wetted surfaces, which can create conditions for microbiological growth if the system is not adequately controlled. Bacteria and other microorganisms can form slime or biofilms on machine surfaces, pipes, showers, and clothing.

Biofilm can trap fibers and mineral particles, turning a thin biological layer into a larger deposit. Pieces can also detach suddenly and enter the process, causing defects or contamination elsewhere.

High-pressure washing helps remove material already attached to the forming fabric, but biological contamination should also be managed at system level. Water loops, tanks, showers, pipes, chemical programs, and dead zones may all need attention.

If biofilm repeatedly returns shortly after cleaning, the cleaner may be treating the symptom rather than the source. Mills should examine microbial-control conditions and shower-water cleanliness instead of simply raising spray pressure.

This same principle applies to many forming-fabric problems: successful cleaning requires both removal and prevention.

Can Forming Fabric Cleaners Remove Mineral Scale?

Mineral scale is different from loose filler contamination.

Calcium salts and other dissolved minerals can precipitate from process water and form hard deposits under suitable temperature, pH, and chemical conditions. Once scale becomes strongly attached to fabric yarns, normal water showers may have limited effectiveness.

High-pressure cleaning can remove loose scale fragments and slow the accumulation of deposits, but hardened scale often requires chemistry targeted to the mineral composition. Before chemical treatment, mills should determine whether the deposit is primarily calcium carbonate, another inorganic material, or a mixed organic/inorganic layer.

Water treatment can also reduce recurrence. If scaling results from process-water chemistry, cleaning the fabric without correcting that chemistry means the deposit will return.

The goal should therefore be:

Remove Existing Deposit + Control the Source + Maintain Continuous Online Cleaning

This generally provides better fabric life than repeatedly using more aggressive cleaning after severe scale has already developed.

How Does a High-Pressure Forming Fabric Cleaner Work?

A high-pressure cleaner uses small nozzles to create concentrated water jets that strike the moving fabric. The impact force breaks the bond between contamination and the fabric yarns, while the water carries loosened material away.

Sun Hong's Paper Machine Felt Fabric High Pressure Cleaning Spray Shower can be configured using pneumatic, electric, turbine-driven, or hydraulic traversing mechanisms. The cleaning pipe moves across the fabric so the jet pattern covers the full machine width instead of repeatedly striking the same narrow line.

Movement is important because a fixed high-pressure needle jet can create a persistent cleaning track if it remains in one position. An oscillating or traversing system distributes cleaning action over the width and reduces the risk of uneven fabric treatment.

The nozzle-to-fabric distance, jet angle, traverse speed, water pressure, nozzle orifice, and fabric speed must work together. A jet positioned too far away loses coherence and impact. One positioned too close can create unnecessary mechanical stress or excessive splash.

The cleaner should remove deposits while leaving the fabric structure unchanged.

Needle Jet vs Fan Spray: Which Removes More Dirt?

Needle and fan nozzles perform different cleaning functions.

A needle nozzle produces a narrow, concentrated water stream with high local impact. It is useful when contamination is lodged inside small openings and the cleaner needs to penetrate the fabric structure. High-pressure needle showers are commonly used for intensive wire and felt cleaning.

A fan nozzle spreads water across a wider area. The impact per unit area is generally lower, but coverage is broader and more uniform. Sun Hong's Paper Machine Fan Type Spray Nozzle can be used for felt and fabric cleaning as well as lubrication, cooling, and other spraying functions.

Many paper machines use more than one shower because the cleaning task changes around the fabric loop. One shower may loosen contaminants while another rinses them away.

The correct combination depends on fabric structure, speed, contamination, available water pressure, and machine layout.

Why Is Nozzle Condition Important?

A cleaner cannot work consistently if its nozzles are worn or blocked.

A partially blocked nozzle produces less flow and an irregular pattern. A worn nozzle may produce excessive flow while losing the concentrated jet shape needed for effective cleaning. Across a wide paper machine, even small differences between nozzles can produce bands of different cleaning intensity.

This can create a confusing operating problem: total shower-water flow may appear normal while parts of the forming fabric remain dirty.

Nozzles should therefore be checked for:

• Clogging

• Orifice wear

• Corrosion

• Misalignment

• Damaged spray pattern

• Incorrect distance

• Uneven flow

• Loose fittings

Cleaning-water filtration is equally important. If particulate contamination reaches small nozzle openings, operators may spend significant time repeatedly clearing blockages.

Nozzle maintenance should therefore be considered part of forming fabric maintenance rather than a separate utility task.

What Happens When a Forming Fabric Is Not Clean?

Loss of cleanliness first appears as a change in permeability. Openings that previously allowed water through easily become partially restricted, so drainage resistance rises.

The mill may compensate by increasing vacuum or changing operating conditions. This can maintain production temporarily but often increases energy consumption and can place additional mechanical stress on the clothing.

As contamination becomes less uniform across the width, drainage also becomes less uniform. Possible symptoms include:

A dirty forming fabric can also contribute to paper defects when deposits disturb the sheet or release contamination into the wet web.

The effect is not always visible immediately, which is why mills often monitor drainage behavior, vacuum, fabric condition, and machine performance together.

Does Cleaning Improve Forming Fabric Drainage?

Cleaning can restore drainage when reduced permeability is caused by removable contamination.

The forming fabric is designed with a specific open structure. As deposits block that structure, water flow falls. Removing fibers, fillers, pitch, or dirt opens the drainage paths again and allows the fabric to perform closer to its intended condition.

However, cleaning cannot restore permeability lost through permanent fabric damage. Yarn deformation, abrasion, heat damage, chemical attack, seam damage, or structural compaction may continue limiting performance even after deposits have been removed.

This distinction is important when deciding whether to clean or replace the clothing.

If permeability improves substantially after washing, contamination was a major cause. If drainage remains poor after thorough cleaning, the fabric structure or another machine condition should be investigated.

The forming fabric should therefore be monitored throughout its service life rather than cleaned aggressively only when performance has already deteriorated.

Can Too Much Cleaning Damage the Forming Fabric?

Yes. A forming fabric cleaner needs enough energy to remove contamination but not so much that it damages the clothing.

Excessively high pressure, incorrect nozzle distance, stationary needle jets, damaged nozzle orifices, poor traverse operation, or an unsuitable spray angle can create localized wear. Repeated impact in the same position can damage yarn surfaces or create visible cleaning stripes.

Older fabrics may also be more sensitive because yarn surfaces have already experienced mechanical abrasion.

Operators should avoid assuming that increasing water pressure is always the solution when cleaning performance falls. Poor cleaning can be caused by worn nozzles, low-quality water, plugged filters, incorrect traverse speed, chemical deposits, or changes in process contamination.

The preferred sequence is:

Identify Deposit → Check Nozzles and Water → Verify Shower Movement → Adjust Cleaning Conditions → Use Chemistry if Necessary

This protects the forming fabric while addressing the actual cause.

How Does Forming Fabric Structure Affect Cleaning?

Single-, double-, 2.5-layer, and triple-layer forming fabrics have different internal geometries. As fabric structures become more complex, they can provide improved fiber support, stability, wear resistance, and drainage characteristics, but contamination may also become lodged in different parts of the structure.

A simple single-layer fabric has a relatively direct open path through the weave. Multilayer designs have more yarn intersections and internal voids where fines and fillers can accumulate. The cleaner therefore needs sufficient penetration to remove contamination from the actual depth of the fabric without damaging the paper-side surface.

Machine speed also changes the available cleaning time. At high speed, each point on the fabric passes the cleaner quickly, so jet quality and traverse coverage become important.

Cleaning settings should therefore be matched to:

• Fabric structure

• Mesh/open area

• Yarn diameter

• Paper grade

• Machine speed

• Fabric age

• Contaminant type

• Shower position

Using the same cleaning setting on every forming fabric may produce unnecessarily aggressive washing on one fabric and inadequate cleaning on another.

How Does a Pressure Screen Affect Forming Fabric Cleanliness?

A pressure screen and forming fabric cleaner perform different jobs, but upstream screening can influence how heavily the fabric becomes contaminated.

The pressure screen removes larger contaminants, shives, fiber bundles, plastics, and other undesirable material before stock enters the approach-flow and forming system. A properly selected screen basket reduces the number of contaminants reaching the headbox.

However, fine fibers, fillers, dissolved materials, colloidal substances, stickies, and process chemicals can still reach the paper machine. The forming fabric cleaner removes the material that actually deposits on the fabric during operation.

The relationship can be summarized as:

Pressure Screen → Reduces Contaminant Load in Stock

Forming Fabric Cleaner → Removes Deposits From the Fabric

Neither one replaces the other.

If stock preparation is poor, the fabric-cleaning system may be overloaded. If the cleaning system is poor, even relatively clean stock can still create deposits over time.

The best paper-machine runnability comes from controlling contamination at multiple stages.

How Does Cleaning Work With Other Paper Machine Clothing Systems?

Forming fabric cleaning is only one part of complete paper machine clothing management.

The fabric must also be guided correctly, tensioned correctly, and protected from mechanical damage. An air bellow in a pneumatic fabric guider can adjust guide-roll position when the fabric begins to drift sideways. The cleaner keeps the structure open, while the guider keeps the clothing in the correct lateral position.

These functions are connected. Heavy deposits can create uneven fabric behavior and may contribute to tracking problems. Poor tracking can move the fabric away from the intended shower coverage or cause edge wear. Excessive tension can make the fabric more vulnerable to high-pressure cleaning impact.

A stable forming section therefore depends on:

Clean Stock + Clean Forming Fabric + Correct Tension + Accurate Guiding + Proper Dewatering Elements

Focusing on only one component rarely produces the best long-term result.

How Can Mills Tell What the Cleaner Is Removing?

Visual inspection can provide some information, but deposit analysis is more useful when contamination repeatedly returns.

Loose fiber deposits are usually easy to identify. Mineral-heavy deposits may feel hard or chalky. Pitch and stickies may appear tacky or oily. Biological slime can feel soft or gelatinous.

For persistent problems, mills can collect deposit samples and determine whether they contain mainly:

• Fiber

• Ash/mineral filler

• Calcium deposits

• Pitch

• Adhesive material

• Microbiological slime

• Coating residue

• Mixed organic/inorganic contamination

Knowing deposit composition helps determine whether the solution is stronger mechanical cleaning, different water chemistry, improved stock screening, chemical deposit control, biocide optimization, or a change in furnish.

Cleaning performance should be assessed by both visible cleanliness and machine response. Improved drainage, reduced vacuum demand, more uniform moisture profile, and fewer deposits are better indicators than appearance alone.

How Often Should a Forming Fabric Be Cleaned?

There is no universal cleaning interval because modern online showers may operate continuously or intermittently throughout production. The appropriate schedule depends on furnish, machine speed, water chemistry, fabric design, paper grade, and contamination rate.

A recycled-paper machine with high stickies loading may require more intensive cleaning than a machine using relatively clean virgin pulp. Machines with high filler use can also experience rapid mineral and fines accumulation.

A practical cleaning program combines:

• Continuous low- or moderate-intensity washing

• Periodic high-pressure cleaning

• Regular nozzle inspection

• Fabric-condition monitoring

• Shutdown cleaning when needed

Waiting until drainage deteriorates severely usually requires more aggressive cleaning and increases the risk of production loss.

Preventive cleaning is generally more effective than trying to recover a fabric that is already heavily plugged.

How to Choose a Forming Fabric Cleaning System

Selection should begin with the contamination problem rather than with pump pressure alone.

Mills should provide the cleaner supplier with:

A mill experiencing recurring pitch and stickies should not specify the cleaner only by width and pressure. Likewise, a mill dealing mainly with filler plugging may need a different cleaning approach.

The purpose of the equipment is not to maximize jet pressure. It is to maintain fabric permeability and cleanliness with acceptable water consumption and minimal clothing damage.

Why Choose Sun Hong Group?

Sun Hong Group was established in 2010 in Xuzhou, Jiangsu Province and originally focused on forming fabrics, press felts, and dryer fabrics. Its business later expanded into paper-machine cleaning showers, spray nozzles, dewatering elements, doctor blades, screen baskets, rolls, rotary joints, pneumatic components, and other pulp and paper equipment.

This background is relevant to forming fabric cleaning because cleaning equipment and the clothing itself need to be considered together. Fabric structure, machine speed, paper grade, yarn construction, contamination type, and shower arrangement all affect the cleaning result.

Sun Hong supplies high-pressure felt and fabric cleaning systems together with needle and fan spray nozzles for different paper-machine applications. Different traversing mechanisms can also be selected according to machine layout and operating requirements.

For a forming-section cleaning project, mills can provide machine width, speed, forming fabric type, water pressure, contamination description, shower position, existing nozzle configuration, and photos or drawings. These details make it easier to select a cleaning arrangement that removes contamination without applying unnecessary mechanical stress to the fabric.

Conclusion

A forming fabric cleaner removes much more than visible pulp fibers.

During papermaking, the fabric can accumulate fibers, fines, mineral fillers, pitch, stickies, coating residues, process chemicals, biological slime, mineral scale, and general dirt. These contaminants can cover yarn surfaces or fill the open structure of the fabric, reducing permeability and disturbing water removal.

High-pressure needle jets are useful for concentrated cleaning and penetration into fabric openings, while fan sprays provide broader and more uniform washing. Oscillating shower systems distribute cleaning energy across the full machine width so that the same narrow area is not continuously exposed to the jet.

Cleaning conditions must be matched to the fabric and contamination. Excessive pressure can damage paper machine clothing, while inadequate cleaning allows plugging to develop. Severe chemical or mineral deposits may require specialized shutdown cleaning rather than simply increasing water pressure.

A forming fabric cleaner also works as part of a larger contamination-control system. A pressure screen reduces contaminants in the stock before the headbox, the cleaner removes material that deposits on the fabric, and an air bellow guider helps maintain correct fabric tracking. Each system performs a different function but contributes to stable forming-section operation.

Sun Hong Group supplies forming fabrics, spray shower systems, nozzles, guiding components, and related paper-machine parts. For a new cleaner or replacement system, provide the machine width, speed, forming fabric design, contamination type, available water pressure, shower position, current nozzle arrangement, and cleaning problem so the cleaning system can be matched to actual mill conditions.

FAQ

What does a forming fabric cleaner remove?

It removes fibers, fines, fillers, pitch, stickies, dirt, chemical residue, biological slime, and other deposits that accumulate on the surface and inside the openings of the forming fabric.

Why do fibers remain stuck in a forming fabric?

Fibers can become trapped around yarn intersections or pushed into fabric openings by drainage forces. Fine fibers may penetrate deeper into multilayer fabrics and combine with fillers or sticky deposits.

Can a forming fabric cleaner remove pitch and stickies?

High-pressure water can remove fresh or weakly attached pitch and stickies, but aged or strongly bonded deposits may require chemical cleaning or upstream process control.

Can a forming fabric cleaner remove calcium carbonate filler?

It can remove loose filler particles and help prevent buildup. Hardened mineral scale may require additional chemical cleaning or correction of process-water chemistry.

What type of nozzle is best for forming fabric cleaning?

High-pressure needle nozzles provide concentrated impact for intensive cleaning, while fan nozzles provide wider and more uniform spray coverage. Many machines use different nozzles for different cleaning duties.

Why is an oscillating shower used on a forming fabric?

Oscillation moves the cleaning jet across the machine width, providing more uniform coverage and reducing the risk of repeatedly striking one narrow track of the fabric.

Can excessive cleaning pressure damage forming fabric?

Yes. Excessive water pressure, incorrect nozzle distance, a damaged nozzle, or a stationary high-impact jet can create local yarn wear or cleaning stripes. Settings should match the fabric and machine speed.

How does a dirty forming fabric affect drainage?

Deposits reduce the effective open area of the fabric, making it more difficult for water to pass through. This can increase vacuum demand and create non-uniform drainage.

Does a pressure screen replace a forming fabric cleaner?

No. A pressure screen removes contaminants from pulp before it reaches the paper machine, while a forming fabric cleaner removes deposits that accumulate directly on the clothing.

Does forming fabric cleaning improve paper quality?

It can help by maintaining uniform drainage and reducing deposits that may disturb sheet formation. Paper quality still depends on stock preparation, headbox operation, fabric design, pressing, drying, and other process conditions.

How often should forming fabric be cleaned?

Many online cleaning showers operate continuously or intermittently during production. Additional intensive or chemical cleaning may be required depending on furnish, additives, contamination, and fabric condition.

Why do forming fabric cleaner nozzles clog?

Nozzles can clog when cleaning water contains suspended solids, corrosion products, scale, or other particles. Proper filtration and regular nozzle inspection help maintain a consistent spray pattern.

What information is needed to select a forming fabric cleaner?

Provide machine width, speed, forming fabric structure, paper grade, furnish, contamination type, available water pressure, water quality, shower position, existing nozzle type, and the current cleaning problem.