Recovered fiber carries adhesives, coatings, inks, binders, and other hydrophobic material into the mill. Once inside, those particles agglomerate, cling to equipment, and show up as defects in the sheet. A 2026 BioResources review ties higher recovered-fiber use and reduced process-water discharge to heavier deposition on forming fabrics, press felts, and dryer fabrics.
This guide covers where stickies come from, how to read the symptoms, a four-part control strategy, and how to verify results with sampling and monitoring.
Key Takeaways
- Stickies control spans fiber quality, water systems, chemistry, equipment, and operating conditions.
- Dispersing, detackifying, fixing, and removing are four different jobs.
- The right treatment depends on the source, the defects, and what you can measure.
- A mill-specific program supports quality, reliability, and less downtime.
What Are Stickies in Recycled Paper?
Stickies are tacky, hydrophobic contaminants that enter the process mainly through recovered fiber. Coatings, additives, broke, and chemical interactions in the system can add more.
Size categories depend on the test method, not one universal boundary:
- Macrostickies are retained by a slotted screen. Slot sizes vary by method and application, from 100 µm to 150 µm.
- Microstickies pass the screen and can stay dispersed in the water.
- Secondary or colloidal stickies form when process interactions cause agglomeration or deposition.
Why are stickies difficult to manage?
Several variables interact:
- Hydrophobic particles tend to self-associate, which favors aggregation and deposition.
- Heat softens some adhesives, but tack response varies by material and method. No universal temperature rule exists.
- pH cuts both ways: one study found more depositable matter at pH 10 than at pH 7, yet higher pH can stabilize anionic colloids and aid early removal.
- Negative surface charge stabilizes stickies; calcium, aluminum, and some cationic polymers can destabilize them.
- Certain cationic polymers have been reported to cause secondary stickies.
Water reuse raises the stakes. With less discharge, contaminants persist and concentrate.
What problems can stickies cause?
Common symptoms include:
- Deposits on wires, felts, dryer fabrics, rolls, or cylinders
- Reduced clothing permeability and poor drainage
- Sheet holes, spots, and blemishes
- Web breaks and unstable runnability
Stickies frequency has been linked to web breaks, and in one study more than half the breaks occurred in the press or early dryer sections. That link is an association, not proof of cause.
Document each symptom by location, frequency, appearance, and production impact. Don't treat any one symptom as proof of a single chemical cause.
Why Recycled Paper Mills Develop Stickies Problems
Where do stickies in recycled paper come from?
The main sources:
- Pressure-sensitive adhesives, which can be highly tacky even in small amounts
- Hot-melt adhesives, common in corrugated packaging and often a large share of OCC furnish contaminants
- Labels and laminated or treated materials
- Coated broke carrying binders such as EVA and SBR
Sources differ by stream. A peer-reviewed grade study found 3-5 wt% stickies in most sampled wastepaper grades and 15 wt% in its curbside grade. Those are sample results, not industry benchmarks, but they show why contaminant load varies by furnish. Identify the high-contributing streams before changing chemistry.
How do water reuse and operating conditions influence stickies?
Closed or heavily reused water loops reduce dilution and purge opportunities. Particles circulate longer and interact more with each other and with machine surfaces.
Temperature swings, storage conditions, pH, hardness, charge balance, and machine chemistry can all change particle behavior. Calcium and magnesium can bridge carboxylates, for example. Conductivity matters in practice, but no stickies-specific threshold is established, so track it as a trend rather than a target.
How can a mill connect symptoms to a likely source?
Map the machine and water loop. Then compare samples from furnish streams, pulper and screening areas, white water, approach flow, headbox, clothing, and deposit sites.
| Symptom | Where to investigate |
|---|---|
| Dryer deposits | Dryer fabrics, felts, broke and coating streams |
| Clothing fouling | Furnish, white water, wet-end chemistry |
| Sheet spots or holes | Headbox, approach flow, dryer fabrics, screening |
These are starting points. One symptom never reliably identifies one source.
How to Control Stickies in Recycled Paper: A Four-Part Strategy
Start with physical removal and source reduction
Keep problem material out first. Core options include:
- Furnish inspection and supplier bale-quality controls
- Screening, cleaning, and flotation
- Washing and filtration
Screening mainly catches larger material. Pressure and temperature can deform stickies so they slip through slots, which is why screening alone falls short. Compare contributions by stream, including broke, to find unusually heavy sources before adding treatment chemicals.
Keep particles dispersed and reduce their tackiness
These are separate functions. Dispersants keep hydrophobic particles small and suspended, limiting the large agglomerates that deposit or reach the sheet.
Detackification, or passivation, reduces the tendency to stick to machinery, fibers, or each other. Talc and bentonite are widely used, and amphiphilic polymers can create a steric barrier.
Selection and dosing depend on contaminant type, furnish, water chemistry, temperature, and application point. Rely on technical references and mill trials, not universal dosage claims.
Fix controlled particles to the fiber
Fixation attaches conditioned microstickies to fiber so they leave with the sheet instead of building up in white water or on machine surfaces. Cationic polymers and filler/polymer systems are used for this.
Timing and location matter. Cationic treatment in water without fibers can promote agglomeration, and poorly placed fixatives can interfere with retention, drainage, strength, or formation.
Evaluate fixation with:
- Particle measurements
- Sheet-quality checks
- Deposit observations
- Machine data
Monitor the system and adjust proactively
Useful methods:
- Process-water sampling and microscopy
- Fluorescent markers with flow cytometry for microstickies
- Particle counting and sizing
- Deposit analysis by FTIR, GC-MS, or tack-force testing
- Turbidity as a colloidal-stability indicator (not a stickies count)
A lower water-phase count does not prove fixation. It could be agglomeration. Pair water measurements with fiber and deposit examination. Then combine lab data with operating indicators:
- Clothing cleanliness
- Drainage and breaks
- Sheet defects
- Cleaning frequency and maintenance notes
Combine the four steps into an integrated program
Effective control combines removal, dispersion, detackification, fixation, and monitoring. Isolated chemical fixes for each symptom rarely hold. Revisit the program whenever furnish, recycled content, water-loop conditions, grade, or temperature changes.
How to Build and Verify a Mill-Specific Control Program
Establish a baseline before selecting treatment
Define the problem in measurable terms:
- Deposit frequency, defects, and clothing permeability
- Drainage instability, breaks, cleaning labor, and lost time
Then document furnish composition, recovered-fiber sources, water-system layout, machine chemistry, operating temperatures, sampling points, and recent process changes.
Characterize the deposits, particles, and process water
Collect samples from the suspected source and the affected machine locations, using consistent timing, preservation, and labeling. Analyze:
- Particle size and count
- Hydrophobic or adhesive character
- Deposit composition
- pH, conductivity, hardness, temperature, and charge demand
Match the method to the question. TAPPI/ANSI T 277 quantifies macrostickies but does not measure microstickies.
Select application points and treatment sequence
Chemistry added near the source behaves differently from chemistry added in the approach flow, white water, wet end, press area, dryer section, or clothing cleaning system. Compare options on:
- Compatibility and product quality
- Worker safety and wastewater requirements
- Equipment limits and the risk of shifting contaminants elsewhere
Run a controlled trial and verify the result
- Change one meaningful variable at a time where practical
- Keep a documented control period
- Track immediate observations and longer-term machine behavior
- Compare particle data, deposit inspections, sheet quality, and clothing condition
- Review cleaning intervals, breaks, downtime, water quality, and chemical use
Use your own records for performance figures. Published cases are vendor-reported and not independent benchmarks. One example: a 2019 report from a 1,600 tons/day recycled-OCC linerboard mill described normalized debris-related downtime falling from 36.1 to 12.7 minutes per day.
Work with an experienced industrial cleaning and deposit-control partner
Paper mills can consult Greystone about a facility-specific combination of cleaning and conditioning chemistries and system or deposit-control practices for difficult recycled-fiber challenges. Its Tri-Solve chemistries and HelioJET hot-water systems address wires, press felts, and dryer fabrics.
Start by diagnosing your process, improving reliability and sustainability, and choosing an approach that supports compliance and safe operations. There is no universal product or guaranteed result.
Treat stickies control as an ongoing improvement program, reviewed as furnish, grades, water systems, and production targets change.
Frequently Asked Questions
What can be made from recycled paper?
Common outputs include tissue, packaging, printing and writing paper, newsprint, paperboard, and molded fiber products. The final use depends on recovered-fiber quality and mill processing.
What are stickies in recycled paper?
Stickies are adhesive or tacky contaminants introduced through recovered fiber. They can form deposits on equipment or defects in the sheet.
Where do stickies in recycled paper come from?
Typical sources are labels, pressure-sensitive and hot-melt adhesives, coatings, binders, and laminated materials. Recycled fiber and coated broke carry them into the mill.
How do stickies affect paper machine performance?
They foul wires, felts, and dryer fabrics, reducing permeability and drainage. Results include sheet defects, web breaks, more cleaning, and unstable runnability.
How are stickies controlled in a recycled paper mill?
Mills combine source reduction, screening and cleaning, dispersion, detackification, fixation, targeted cleaning, and ongoing monitoring.
How can a mill monitor stickies?
Use representative sampling, deposit analysis, microscopy or fluorescence testing, particle counting, and process-water measurements. Pair them with indicators such as breaks, drainage, and clothing condition.
