Two wipes can look identical in a photograph and behave differently at the edge. A cut edge is a line of severed fibres; a sealed edge is a welded border; a laser edge is a cut that has been melted closed as it was made. The difference shows up in a particle count, in a scratch on a coated surface and in the price.
What a cut edge actually does
Cutting leaves loose fibre ends along the perimeter. In a utility area that is acceptable: the cloth is used for general wiping, the room is graded ISO 7 or 8, and the fibre load is small relative to the soil being removed. In a critical area the same edge is a source that sits inside the clean zone for as long as the cloth is in use.
Cut edges are also the cheapest to convert, which is why they dominate the volume market. The mistake is not buying them; it is buying them for a task where the edge is the dominant particle source.
Sealed edges, two ways
Ultrasonic sealing welds the fibres with mechanical energy. It produces a soft, continuous border and works well on thermoplastic blends. The seal width is the quality parameter: a narrow or interrupted seal leaves an unsealed run that behaves like a cut edge, and it is invisible without magnification.
Laser sealing cuts and fuses in one pass. The border is narrower and harder, and it can be used on polyester and microfibre where a wide ultrasonic band would stiffen the cloth. The trade-off is a slightly abrasive edge, which matters on soft coatings.
| Edge | Particle shed | Surface risk | Relative cost | Typical area |
|---|---|---|---|---|
| Cut | Highest at the perimeter | Low | 1.0 | ISO 7–8 utility |
| Ultrasonic | Low | Low | 1.3–1.6 | ISO 5–7 |
| Laser | Lowest | Moderate on soft coatings | 1.5–1.9 | ISO 5, optics, sterile |
How to verify what you bought
Ask for the seal width and the method used to measure it. Then check a sample yourself: cut a strip across the edge, inspect at 10×, and look for a continuous weld line with no fibre ends projecting beyond it. A seal that disappears at a corner is a converting fault, not a design choice.
For laser edges, look for a continuous fused line and no charring. A brown edge on a white cloth is either a setting problem or a different material, and both are worth a question.
The decision in practice
Work from the surface backwards. If the surface can tolerate a fibre and the room is ISO 7 or 8, a cut edge is the economical choice and the specification should say so. If the surface is coated, inspected or sterile, the edge should be sealed, and the seal should be a named parameter rather than an adjective.
There is one more case: a cut edge used wet. Once the cloth is saturated, loose fibres adhere to the surface and are harder to see and remove. A wet cut-edge wipe on a critical surface is the worst combination in this family, and it is common because the cloth looks and feels the same.
Cost per clean, not cost per wipe
A sealed-edge wipe can cost 50% more per sheet and still be cheaper per clean if it removes the second pass that a shedding edge would require. That is the comparison to make: passes per surface, not price per pack.
For a utility area, the arithmetic usually favours the cut edge. For a critical surface, the second pass is not a cost, it is a risk, and the sealed edge is the cheaper option even at the higher unit price.
Does a sealed edge make a wipe cleanroom-safe?
No. It removes one particle source. The fibre, the binder and the packaging still determine the particle and extractable profile.
Can a cut-edge wipe be used in ISO 6?
Sometimes, with data. If the particle release from the cloth is below the room's action level during use, the edge is not the limiting factor. Without that data, use a sealed edge.
Is a wider seal always better?
No. It adds stiffness and cost. The requirement is continuity, not width, and the width should be specified against the converting drawing.
