ISO 14644-1 tells you how many particles are allowed in a cubic metre of air at a given size. It does not tell you which wipe to buy. The gap between those two statements is where most classification arguments happen.
The standard is a useful anchor, though, because it gives a shared language for the room. Once the class is fixed, the consumable decision becomes a series of engineering choices rather than a matter of preference.
The numbers, briefly
The 2015 revision defines classes ISO 1 to ISO 9 by maximum permitted particle concentrations at six sizes. The ≥0.5 µm column is the one most often quoted in procurement documents.
| Class | ≥0.5 µm per m³ | Typical use |
|---|---|---|
| ISO 5 | 3,520 | Aseptic filling zones, critical electronics |
| ISO 6 | 35,200 | Sterile support areas, semiconductor back-end |
| ISO 7 | 352,000 | Clean assembly, pharmaceutical support |
| ISO 8 | 3,520,000 | General clean manufacturing |
Note that the class describes the air, not the surfaces, and not the consumable. A wipe used in an ISO 7 room can still deposit particles far above the room's background if it is the wrong construction.
What changes with each class
The practical differences between classes are edge finish, fibre selection and evidence. Weight and absorbency are secondary; a heavy wipe with a cut edge is not an ISO 6 product.
ISO 8 is forgiving. A wood pulp or cellulose blend cloth with a cut edge is usually acceptable, provided the room is not also controlling surface contamination tightly. The evidence package can be modest: material declaration and a particle count.
ISO 7 is where edges start to matter. Sealed or laser-cut polyester, or a high-quality non-woven with a folded edge, is the norm. Extractables data becomes relevant if the surface is painted, coated or later sealed.
ISO 6 calls for a low-shedding fabric, typically knitted or laundered polyester, with documented particle and fibre release. Cut edges are difficult to defend here unless the wipe is used in a way that never presents the edge to the surface.
ISO 5 and Grade A add sterility and transfer discipline. The wipe must be sterile where it contacts a sterile surface, individually bagged or double-bagged, and traceable to a lot. Particle data alone is not sufficient; the transfer process is part of the specification.
Many sites run ISO 8 rooms with ISO 7 consumables because the product is sensitive, not the air. Decide from the product, then check that the class permits it.
The evidence ladder
Each step up in class adds a document, and each document should be specific to the reference rather than the product family.
- Material declaration and safety data.
- Particle count by a named method, with the unit basis stated.
- Fibre release and edge-shedding data.
- Extractables and residue data, with the solvent named.
- Sterility assurance, bioburden and packaging validation.
- Lot traceability and change notification.
Most audits do not ask for all six. They ask for the ones implied by the class and the product contact. Holding the full ladder for a Grade A reference and the first two rungs for an ISO 8 maintenance cloth is a defensible position.
Where classification arguments go wrong
Two mistakes recur. The first is using the room class to justify a consumable that is cheaper than the application requires, then discovering the gap during a media fill or a customer audit. The second is over-specifying every wipe to the highest class, which raises cost without changing risk.
The resolution is to classify the task, not just the room. A wipe used on a floor drain in an ISO 7 suite does not need the same reference as one used on a filling needle. Write both into the cleaning instruction, with the reference named.
A short worked example
An ISO 7 room packs sterile devices. Two tasks: bench wipe before transfer, and floor wipe at the end of shift. The bench task contacts a surface that will be bagged, so the wipe should be sealed-edge polyester with extractables data. The floor task contacts a non-product surface, so a cut-edge pulp cloth is adequate.
Same room, two references, two evidence levels. That is not inconsistency; it is a specification that reflects what the wipe actually touches.
Is an ISO 14644 certificate required for a wiper?
No. Certification applies to cleanrooms, not consumables. What you need is test data from a recognised method and a lot traceability system.
Can I use ISO 8 wipes in an ISO 5 zone?
Only if the wipe is sterile, low-shedding and transferred correctly. The room class does not upgrade the consumable; the consumable has to meet the zone's requirements independently.
Does the standard require a specific wiper test?
No. ISO 14644-1 is about airborne particle classification. Wiper testing is covered by separate recommended practices, most commonly IEST-RP-CC004.
The class tells you what the air must be. The specification tells you what the wipe must be. Keep the two documents separate and the audit conversation gets much shorter.
