Quality. When It’s Wrong, You Will Feel It
- Published: June 1, 2026, By Trevor
By Neal Michal, Principal at Converting Expert, LLC
Credit: Converting Expert, LLC
Does your web run flat through your customer’s converting process? Do they see wrinkles, baggy lanes, or floppy edges? Do they see hard-folded creases in your laminated product?
Let’s discuss “Lay Flat.” Few understand it. Fewer test for it.
Definition
A web that lays flat is a high-quality material that provides higher yield and lower waste.
Poor lay flat is the most common root cause for wrinkles, floppy edges, and baggy lanes.
Root Cause
A persistent cross machine direction (CD) variation of caliper, moisture, temperature, or residual strain from manufacturing is the most common root cause for poor lay flat. Most webs are stored in wound rolls. Persistent CD variation + wound roll stresses + time results in poor lay flat web.
What should you do when faced with a web that misbehaves? Detect, Document, and Act.
Detect
Begin by reviewing the converting process to look for evidence of poor lay flat. This should be done while the process runs under tension and during a stop when the web is at low tension.
Wrinkles have three levels of severity: troughs, wrinkles, and creases. Troughs are small out of plane deformations. They are the early warning sigh before wrinkles appear. Troughs are often angled 10-20° from the machine direction (MD). Troughs will often form a wrinkle at the end of a long web span or as the web passes around a roller with high traction. A crease is a permanent hard folded wrinkle that continues down the process.
Shine a light across the web from side to side at a shallow angle. Document the size, shape, and severity. Are the troughs angled? Where are they located on the web? Look across the top of the web to determine if there are baggy lanes. How many are there? How wide? Where are they located?
Look across the bottom of the web to see if there are floppy edges. Do the edges drop down? How much? How far from the edge does the slackness extend?
Take pictures or a video. Make a sketch to document type, location and severity.
Document
For a short period of time, collect lots of data. Document everything:
Test the Roll
A wound roll can store thousands of web layers. Any persistent variation in one position will build upon itself. The winding process often gets blamed when all it does is accumulate a persistent deviation into a wound roll.
The wound roll has evidence of the crime. Run your hand across the face of the roll. Close your eyes. Focus on what your fingers are telling you. How many humps and valleys do you feel? Where are the large deviations?
For closer inspection, lift the roll up off the floor and support it through the core. Be safe. Measure the diameter variation across the face of the roll. Ideally use a “Pi Tape” which can measure within one mil (0.001”) accuracy.
Conduct a “Roll Out Floor Test”. Remove 40 feet of web. Carefully lay it out on a smooth floor. Document severity and position for baggy lanes and floppy edges.
Document caliper and mass profile across the deckle. Cut one full width sample that is about one foot long in the machine direction. Document caliper for every inch across the web from operator (OP) to drive (DR) side. Cut corresponding coupons from this sample. Ideally 1” or 2” wide (CD) x 10” long (MD) with small gaps in between. Weight each sample.
Graph the caliper and mass profile. They should correlate. Note any significant changes from local minimum to maximum values. High caliper / basis weight zones will be closely associated with poor lay flat.
All films are sensitive to temperature. Document the temperature profile across a full roll directly after winding. Ideally use a long wave IR camera. Graph this information.
Measure the roll hardness across the face of a full roll. There are various testers available. It has been proven that rolls with high variability combined with higher average hardness will convert poorly.
ACA RoQ Roll Hardness ProfilerCredit: Industrial Physics
Harvest Online Tools
There are many online quality monitoring devices. Basis weight monitors are common for paper machines and some closed loop film processes. Some basis weight monitors may provide a moisture profile. Some film processes will have IR scanners to document the temperature profile across the web.
Harvest the information from your online monitor(s) that represents the entire roll build time. Graph the numerical data.
Act
It is important to have metrics in place to determine if an improvement has been achieved.
Work with your customer to establish visual standards for wrinkles, creases, baggy lanes, and floppy edges. Each defect should be named with a picture. This should be included in a release specification.
For a short period of time, collect lots of data. Document everything.
Compare the graphs that you have collected. Establish a correlation between persistent cross deckle variation(s) and poor lay flat. Lanes with high caliper / high basis weight / high temperature / high moisture will display poor lay flat.
Conduct an internal review of the data. Determine what should be done going forward. Commission a program to reduce cross deckle variability.
It is possible to reduce poor lay flat by reducing winder tension, nip and torque. All films benefit from being cooled off to below room temperature before winding. Avoid storing film rolls in hot environments.
Implement wound roll quality metrics such as average roll hardness / density, variations in roll hardness across the width, variations of slit roll density across the width, moisture and temperature profile. Add these metrics to your internal manufacturing specifications.
Conduct aged roll testing. Work with your customer to run controlled converting trials.
Focus on reducing variability using your metrics.
Conclusion
The ideal web will lay flat in the converting process. If not, focus on reducing CD variability which will provide improved lay flat and converting performance.
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://convertingexpert.com/