Roll Blocking: Root Cause & Solutions
- Published: February 27, 2026, By Trevor
By Neal Michal, Principal at Converting Expert LLC
Web handling is a process science which includes tensioning, web conveyance, wrinkles, spreading, winding and unwinding.
Roll blocking is a major defect in which layers of a wound roll stick together. Although it occurs inside the wound roll, it becomes apparent at the unwind, where the web fails to release smoothly.
Definition
Roll blocking is the unwanted adhesion of adjacent layers stored in a wound roll. Roll blocking will be seen at the unwind. The web will not release smoothly from the roll. Blocking is common with films but may be seen on other web substrates.
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Intermittent stick and release will cause tension disturbances which may stretch the web. Blocking related defects include floppy edges, baggy lanes, wrinkles, steering problems, visual defects, registration errors, or optical defects.
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Assessment
First, assess the severity of the blocking at the unwind. Note how the web releases from the roll and how it impacts your process. Minor roll blocking may be okay if the web exits the roll consistently but may increase near the core. Rolls with major blocking will cause defects, waste, or stop occurrences. Rolls with severe blocking may back wrap resulting in a web break.
Assessing the Blocking Severity
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Roll blocking is a serious defect with a significant cost impact. Calculate the cost impact across the supply chain. Roll suppliers and converters should work together to determine the total cost impact. Documenting the cost will facilitate constituency with management to make improvements.
Improvement Options
There is a wide range of factors that result in roll blocking. The fundamental issue is web chemistry. Contributing factors include time, temperature, winding, roll geometry and storage conditions.
There are three categories for improvements: unwind, web substrate and wound roll. Refer to the table for options to address roll blocking.
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Work across the supply chain to try different things. Note process changes. Focus on delivered cost.
Converting Process
If you are the converter, try unwinding with higher tension. Roll blocking is time and temperature dependent. Document the age of the roll and its temperature history. Collaborate with your supplier to add temperature loggers to track the roll from manufacturing to the converting unwind.
Consider adding a peel roller to the unwind. A peel roller sits on top of the unwinding roll. This will require changing the unwind rotation. This modification often eliminates the concern.
Manufacturing Process
If you make the web and wound roll there are more options to consider.
Start with the basics. Improve your delivered quality across the width of your process and in between production campaigns. Work with your operations team to document best practices and follow them. Improve process health cleaning. Pay attention to the details.
For the balance of this paper, the author will assume roll blocking for film rolls. These factors will have application for other web substrates.
We will look at seven factors for film.
1. Surface Chemistry
Polyethylene (LDPE, LLDPE) and polypropylene (PP, BOPP) are more prone to block than other films. Anti-block additives are a common solution for films. Work with your film vendor to explore options such as erucamide, oleamide, silica or talc.
2. Web Topography
The surface topography of the film refers to the microscopic texture or roughness. Films with higher roughness block less because they trap more air in between layers. Use a matte finished casting drum instead of a smooth drum. Embossed films trap more air and are less likely to block.
For a given surface chemistry and web topography the next opportunity is winding as it determines interlayer pressure.
3. Winding
Winders use tension, nip, and sometimes torque to convert a flat web into a wound roll. These are referred to as the TNTs of winding. Tension is the big knob; nip load has a smaller impact. Torque may be used for differential shaft winding.
All webs stored in a wound roll result in a unique shape for interlayer pressure and stored machine direction? (MD) strain. Roll blocking is linear to interlayer pressure which is the contact force each layer experiences from their adjacent layers.
For film, interlayer pressure is at its maximum at the core and decays logarithmically to the outside diameter. This is why blocking is more common near the core. Interlayer pressure will vary with Winder TNTs. The red curve represents high TNTs, blue for medium TNTs, and green for low TNTs. Trial winding softer rolls as measured by roll hardness or density. First reduce tension, then nip load. Note that winding a softer roll comes at a risk due to increased handling damage or flat spots. Roll handling, packaging and storage improvements may be required.
Hold trial rolls for several days for evaluation. Test one roll immediately. Test subsequent rolls based on log time. Unwind the rolls to determine if blocking has been reduced to an acceptable level.
Interlayer pressure for film rolls dramatically increases with roll length. Trial running shorter rolls. Reducing roll diameter from 30” to 24” can reduce pressures at the core by 50% which may eliminate roll blocking.
If blocking is close to the core, trial winding using larger coreshafts:
(3” à 6” à 6.75” à 8” à 10”, etc)
Your customer may require core adapters short term or new spindles long term. If larger coreshafts are not available, trial custom fiber cores with an exceptionally large:
OD (EG: 3” ID x 7” OD).
Note that roll length will drop when converting over to larger cores. This is typically 3-5%. It is easy to add that back on the outside of the roll.
Trial using a more compliant nip roller at the winder. Lower durometer and/or a thicker cover may reduce local roll blocking.
Scatter winding is a technique used to mitigate gauge bands. The winder can be moved back and forth (operator to drive) to spread out the impact of the gauge variation at the expense of total width that can be sold to the customer. Another approach is to place a steering roll that moves the web in a controlled fashion leading into a fixed winder. It is easier to move the web than the winder.
4. Gauge Variations
Roll blocking may be located in individual lanes across the width of the film roll. Thick gauge bands magnify interlayer pressure resulting in discreet lanes that are blocked.
Gauge variations are difficult to measure but can be easily seen in the wound roll. Document gauge variation across the width. They are often repeatable over time. World class gauge variations will not exceed 3%. Some processes achieve 1%.
The short-term solution to clean the die. If the issue continues to persist, the entire die may require disassembly for better cleaning. If capital is available, the use of a basis weight monitor can be used to control the die lip gap profile.
5. Temperature
Most films are sensitive to temperature due to a semi-crystalline nature and low glass transition temperature. High temperatures will facilitate roll blocking. This applies to the film, the roll, storage, and shipping.
Measure the temperature of your film and the wound roll. A long wave IR camera is the best. A relatively low-cost IR module can be paired with a smart phone. Both can provide a picture of the temperature profile across the width of the web or roll. A single point IR thermometer will only provide temperature where the laser points.
If possible, reduce the film to below 70°F (21°C) before it enters the wound roll. Chilled rolls are more effective than a curtain of cooled air. If you are using a surface winder, consider retrofitting a cooled winder drum. Cooled nips are another option.
For sensitive webs, refrigerated storage and/or shipping may be required.
6. Viscoelasticity
Most films have viscoelastic properties. Viscoelasticity refers to a property of the material that exhibits both time dependent (viscous) and elastic behavior when deformed. Some films stretch while stored in the wound roll. Any film that shrinks over time will magnify roll blocking.
Highly oriented films tend to return to their original shape. Machine Direction Orientation (MDO), Cross Machine Orientation (Tenter frame), and blown film processes are used to stretch films to their final (thinner) gauge. Stabilize the film by annealing and quenching across temperature-controlled drums.
7. Time
Roll blocking is a time related defect. Blocking will increase over time. Most roll defects will be present within 72 hours of production. Develop trial plans that consider roll aging. More specifically use log time in seconds (10s, 100s, 1,000s, 10,000s, 100,000s, 1,000,000s). For reference, one day is 86,400s, one week is 604,800s.
Although not common, some manufacturers will wind soft rolls of film and rack them for multiple days of aging. They are then processed on a slitter/rewinder to finished customer specifications.
Conclusion
Roll blocking is a serious defect. Extreme tension variations at the unwind result in visual defects, waste and delay. Asses the severity at the unwind. The converter can try to increase tension or modify the unwind using a peel roller.
There are proven solutions to optimize the surface chemistry and roughness to eliminate blocking. Stabilize the web by annealing and quenching. Cool the web off before winding. Pay attention to time and temperature in storage and shipping. Blocking is closely associated with interlayer pressure. Wind softer rolls by reducing tension, then nip. Larger cores can address local blocking. Shorter rolls are an option.
About the Author
Neal Michal was Kimberly-Clark’s senior web handling expert and was responsible for winding and converting performance. He is a technical advisor for the Association for Roll-to-Roll Converters and is a regular contributor to Converting Quarterly and Paper, Film and Foil Converting magazines. Neal can be contacted at This email address is being protected from spambots. You need JavaScript enabled to view it. (770) 356-7996. Learn more at: https://convertinge