Contents
- How to use this guide
- What are pitch & stickies (and why recycled fiber is harder)
- Map the problem: where deposits form
- Control options (detackify, fix, disperse, remove)
- Decision matrix: which chemistry to start with
- Dosing points & control strategy
- KPIs, tests & monitoring signals
- Procurement specs & acceptance checks (COA/SDS)
- Troubleshooting: symptoms → likely causes
- RFQ notes
- FAQ
How to use this guide
This guide is designed for recycled-fiber mills, stock-prep teams, and purchasing/EHS stakeholders. Use it to align on (1) root cause (what contaminants are present), (2) control mechanism (detackify vs fix vs removal), and (3) commercial execution (consistent product quality, dosing stability, and clear acceptance criteria).
Practical rule: “Stickies control” is rarely one product. The best programs combine early capture (fix/removal in stock prep) + machine protection (detackify/disperse near the approach flow) + good housekeeping (wash programs, pitch dispersants where needed).
What are pitch & stickies (and why recycled fiber is harder)
In recycled fiber, the main deposit drivers are “tacky” organic contaminants plus secondary deposits driven by system closure.
Stickies (recycled fiber)
- Primary stickies: PSAs (pressure-sensitive adhesives), hot melts, latex binders, coatings, inks, labels, tape residues.
- Behavior: soften with temperature, become tacky at certain pH/ionic conditions, agglomerate into larger particles.
- Risk: deposits on wires/felts/rolls, sheet defects, breaks, holes, edge build-up, and downtime.
Pitch + secondary deposits
- Pitch-like hydrophobics: extractives/resins that may appear depending on furnish mix.
- Secondary deposits: “sticky + fines + calcium + starch + ASA/AKD + microbiology” complexes.
- Closure effect: high DCS/OCS increases anionic trash and destabilizes wet-end chemistry.
Map the problem: where deposits form
Start with a deposit map. The same contaminant behaves differently depending on where it lands and what chemistry is present.
- Stock prep: pulper, coarse/fine screens, cleaners, dispersion/kneading (if present), thickener.
- Approach flow: machine chest, fan pump, pressure screens, headbox.
- Wet end / press: forming section, press felts, Uhle boxes, saveall/white water.
- Dry end: dryers, calenders, reels—often where softened stickies become a visible issue.
What to document
- Where deposits appear (photos help)
- Deposit character (tacky, greasy, hard scale, slimy)
- When it spikes (grade change, temperature, closure)
- Current wet-end recipe (retention aids, starch, sizing)
Fast field checks
- pH and temperature in critical loops
- Conductivity / closure trend
- White water turbidity trend
- Microbiology indicators (odor/slime)
Commercial constraints
- Packaging: drum / IBC / bulk
- Feed equipment: pump compatibility
- Storage limits / temperature
- Documentation: SDS/COA, lot traceability
Control options (detackify, fix, disperse, remove)
1) Detackifiers (reduce tackiness + prevent agglomeration)
Detackifiers work by coating tacky particles, reducing surface stickiness, and limiting coalescence. They are commonly used near the machine to protect wires/felts/rolls and reduce sheet defects.
- Best fit: deposit-driven downtime, tacky build-up on felts/rolls, sheet defects (holes, spots), press section issues.
- Trade-offs: overdosing can interfere with sizing/strength or create foaming/poor drainage depending on chemistry.
- Commercial note: detackifiers are performance-sensitive; consistent active content and stable formulation matter.
2) Fixatives / passivators (attach contaminants to fiber/fines)
Fixatives reduce “anionic trash” and immobilize dispersed stickies onto fibers/fines so they leave the system with the sheet. This is often a foundation step in closed white water systems.
- Best fit: high DCS/OCS, unstable retention, frequent breaks, deposits that correlate with conductivity/closure.
- Typical chemistries: cationic polymers and coagulants (program-dependent).
- Trade-offs: can change drainage/formation; needs coordination with retention aids and sizing.
3) Dispersants / stabilizers (keep particles small and non-depositing)
Dispersants prevent agglomeration and keep hydrophobic particles from depositing by stabilizing them in the water phase. Often used as a supporting tool in combination with fixation and good cleaning.
- Best fit: deposits that appear after temperature/pH swings, dryer deposits, “greasy” build-up.
- Trade-offs: if you only disperse without removal, you may move the problem downstream.
4) Mineral adsorbents (capture stickies on a solid surface)
Minerals can reduce tack by providing adsorption sites and turning sticky contaminants into “non-tacky” complexes.
- Best fit: programs needing robust and simple control; can complement fixation and detackification.
- Trade-offs: ash load impact, retention and drainage changes, cost per ton depends on required dosage.
5) Enzymes and specialty approaches (site-specific)
Enzyme-based programs can target certain adhesive components or aid in contaminant modification. Applicability is highly furnish- and process-dependent and should be validated with trials.
Commercial note: “program economics” beat “chemical price”
Stickies costs show up as downtime, broke, cleaning labor, and quality claims. The best RFQs compare options on cost per ton at target performance and on runability KPIs (breaks, cleaning frequency), not only unit price.
Decision matrix: which chemistry to start with
| Observed situation | Most likely driver | Good starting move | What to monitor |
|---|---|---|---|
| High breaks + deposits on felts/press rolls | Tacky stickies reaching the machine | Detackifier near approach/wet end + verify upstream removal | Cleaning frequency, breaks/day, felt condition, defect count |
| System instability with closure (conductivity rising) | Anionic trash / colloidal destabilization | Fixative/coagulant in stock prep / machine chest; align with retention program | Retention, drainage, white water turbidity, charge demand (if measured) |
| Small particles pass screens; downstream deposits | Dispersed micro-stickies | Fixation + adsorbent upstream; consider dispersion control | Micro-stickies trend, sheet defects, deposit mass/area |
| Odor/slime + sticky deposits | Microbiology + organics complexing deposits | Deposit-control + microbiology management (site EHS rules apply) | Slime reports, ORP/biological indicators, shutdown cleaning needs |
Dosing points & control strategy
Dosing locations matter as much as chemistry. The goal is to treat where mixing is good and before the problem becomes “machine-side.”
Common dosing points (practical)
- Pulper / pulper chest: early capture and stabilization; useful for fixation and some detackification programs.
- Before fine screens/cleaners: improves contaminant removal performance and reduces downstream load.
- Machine chest / thick stock: stabilizes approach flow; common point for fixatives/coagulants.
- Thin stock / white water loop: protects the wet end; common point for detackifiers and deposit-control aids.
Control mode
- Baseline continuous feed for stability (especially with closure).
- Event-based trim for furnish changes, grade changes, or known “bad bales.”
- Change-control discipline: if furnish changes, re-baseline KPIs before increasing dosage blindly.
KPIs, tests & monitoring signals
Track a small set of signals consistently. You want fast feedback without building an over-complex lab program.
Operational KPIs
- Breaks/day (and where)
- Cleaning frequency (felt/roll/wire washes)
- Broke rate and quality rejects
- Deposit mass (trap screens / filters) trend
Process signals
- White water conductivity (closure proxy)
- pH and temperature (tackiness sensitivity)
- Retention / drainage stability
- Turbidity / solids trend in loops
Testing (choose what fits your site)
- Deposit characterization: simple solvent/heat response, microscopy (if available), or supplier-supported analysis.
- Stickies measurement: mill-available methods vary; the key is consistency of sampling and comparison vs baseline.
- Machine inspections: standardized photo points at known hot spots.
Procurement specs & acceptance checks (COA/SDS)
Deposit-control products are performance-sensitive; consistent batches reduce “mystery drift.” Specify what receiving can verify and what operations needs for stable dosing.
| Category | What to request | What to verify on receipt |
|---|---|---|
| Identity & traceability | Product name, grade, manufacturer, lot/batch, production date | Lot matches COA; labels intact; traceability preserved |
| Actives / formulation control | Active content/solids %, density, pH range, viscosity range (as applicable) | COA within agreed ranges; no separation/freezing damage |
| Handling / dosing | Recommended dilution, pump compatibility notes, storage temperature limits | Packaging suits feed system; storage conditions available |
| Safety | Current SDS, PPE guidance, incompatibilities | SDS revision current; EHS review complete |
| Logistics | Packaging (drum/IBC/bulk), lead time, shelf life | Delivery cadence matches consumption; shelf life acceptable |
Troubleshooting: symptoms → likely causes
| Symptom | Likely causes | Fast checks |
|---|---|---|
| Sheet breaks increase | Deposits on felts/wires; retention instability; furnish change | Check deposit hot spots, conductivity, retention/drainage, recent furnish changes |
| Felt plugging / press deposits | Tacky agglomerates; overdosing of certain chemistries; poor wash strategy | Verify dosage and feed point; review wash program; inspect deposit character |
| Odor / slime + deposits | Microbiology and organics contributing to secondary deposits | Check temperature/closure, slime reports, cleaning frequency; review bio-control plan under EHS rules |
| More defects (holes/spots) | Micro-stickies, poor fixation, screens overloaded | Inspect screening performance, adjust upstream capture, review fixative + retention balance |
RFQ notes (what to include)
- Furnish: OCC/ONP/OMG mix, coated grades %, seasonal variability, known “bad” sources.
- System: closure level, conductivity range, pH/temperature profile, key loop volumes.
- Problem statement: where deposits occur, photos, downtime/cleaning frequency, defects and broke %.
- Current program: wet-end recipe (retention, starch, sizing, defoamer), current stickies products and dose points.
- Constraints: food-contact, VOC restrictions, local EHS handling limits, discharge considerations.
- Packaging/logistics: drum/IBC/bulk preference, lead time expectations, storage temperature constraints.
- Acceptance: target KPIs (breaks/day, cleaning interval) and evaluation window (e.g., baseline vs 2–4 weeks trial).
Want a trial plan + supply-ready options?
Share your furnish mix, where deposits appear (photos), closure indicators (conductivity/pH/temp), and your current wet-end recipe. We’ll propose a shortlist (detackifier/fixative/adsorbent options) with COA/SDS expectations, dosing points, and a simple KPI-based trial protocol.
FAQ
Detackifier vs fixative—what’s the difference?
Detackifiers reduce tackiness and agglomeration (often used for machine protection). Fixatives immobilize contaminants by attaching them to fibers/fines to be retained and removed with the sheet. Many mills use both: fix upstream for system cleanliness, detackify near the machine to prevent deposits.
Why did our program work for months and then fail?
The most common reasons are furnish changes (more PSA/hot melt), higher closure (conductivity rise), temperature swings (tackiness increases), or changes in wet-end chemistry (retention/sizing/defoamer). Re-baseline KPIs and verify dosing points and mixing before simply increasing dosage.
Should we focus on removal equipment or chemistry?
Both. Equipment (screens/cleaners) reduces the incoming load, while chemistry prevents what remains from becoming deposits. The best economics usually come from “reduce the load early + protect the machine.”
Educational content only. Always follow site EHS rules and supplier SDS/TDS for safe handling and use. Performance depends on furnish mix, closure level, and wet-end chemistry. Share your constraints and baseline KPIs for a tailored shortlist.