Published: 2026-10-16 · Category: Quality
Problems rarely appear from nowhere. Most disputes can be narrowed along one chain: raw material → forming → impregnation and curing → slitting and winding → storage and transport → customer assembly. The table below maps the common symptoms to the stage worth checking first.
Symptom to likely cause
| Symptom | Check first | Common cause |
|---|---|---|
| Cracking when pleating | Impregnation / environment | Over-cured and brittle; low workshop humidity; pleating set too tight |
| Crushed element, uneven pleats | Stiffness / storage | Insufficient stiffness; moisture uptake; excessive assembly pressure |
| Delamination, blistering | Impregnation | Uneven pick-up; incomplete cure; local high moisture |
| Linting, dust | Slitting / raw material | Fuzzy cut; weak fibre bonding; worn slitting knives |
| Permeability varies by batch | Raw material / forming | Fibre blend drift; unstable weight control; calendering changes |
| Early blocking in service | Grade choice / duty | Not enough media area; higher contamination than assumed; surfactants present |
A workable sequence
- Establish reproducibility: is it one roll, one batch or everything, and is it tied to a machine or shift?
- Check the records: weight, thickness, permeability, resin content and cure parameters for that batch against a known good one.
- Check storage and use conditions: warehouse humidity, tempering, time since opening - easy to overlook, large in effect.
- Reproduce the customer process: run the same pleating parameters to separate a paper issue from a converting issue.
- Keep samples: retain both the problem sample and a good sample for later comparison.
Two ways to misread the evidence
- Calling a process problem a material problem: pleating cracks are sometimes low workshop humidity or too fast a pleating speed.
- Calling a material problem a process problem: if delamination appears on several customers' lines, go back to impregnation and curing.
In short: collect the symptom, the batch, the storage conditions and the customer's process together and most cases narrow in two or three rounds. Send a problem sample with the batch details and conditions if you want us to look at it.