If contamination levels in your cleanroom are spiking after a cleaning cycle, the wiper might be the cause — not the cure. Using the wrong wiper for your ISO class, or using the right wiper incorrectly, can introduce more particles than were present before cleaning.
Why the Wrong Wiper Makes Contamination Worse
Wipers that shed fibres deposit particles directly onto the surface being cleaned. A standard non-woven polypropylene wiper — adequate for general industrial use — is not appropriate for ISO Class 6 or below. Even low-lint wipers require proper folding technique to prevent cross-contamination between surface passes.
The goal is not just to clean a surface. It is to remove particles from the surface without depositing new ones — and without generating additional particles from the wiper itself.
Wiper Types Matched to ISO Class
| Wiper Type | Suitable ISO Class | Typical Application |
|---|---|---|
| Non-woven polypropylene | ISO 8–9 | Entry-level cleanroom, general wipedown |
| Knitted polyester (dry) | ISO 6–8 | Electronics assembly, equipment wipedown |
| Knitted polyester (IPA-saturated) | ISO 5–7 | Critical surface cleaning, semiconductor areas |
| Laundered sterile polyester | ISO 4–6 | Pharmaceutical, medical device, biotech |
| Microfibre (low-particle) | ISO 5–7 | Optics, precision surfaces, equipment seals |
Pre-Saturated vs Dry With Separate IPA
Pre-saturated wipers are convenient and eliminate the risk of over-wetting. However, the IPA concentration decreases as the bag is opened and reused — each successive wiper in an opened bag may have less IPA than the last. For critical-level cleaning, dry wipers with controlled IPA application from a sealed dispenser provide more consistent contamination control.
In ISO Class 5 environments and below, use only high-purity IPA (99.5% purity or above) to avoid introducing residue from impurities in standard-grade isopropanol.
The Folding Technique That Prevents Cross-Contamination
This is the step most facilities skip. Fold the wiper in half, then in half again. Each pass uses a clean face. Never make a return stroke with the same face used on the forward pass. Dispose after four passes — one per quadrant of the folded wiper. This parallel folding and single-pass technique is standard practice in ISO Class 5 training but is rarely explained to operators at ISO Class 7 and above, where it is equally important.
ESD-Safe Wipers: When Anti-Static Properties Matter
In ESD Protected Areas, standard polyester wipers generate triboelectric charge during use. ESD-safe wipers incorporate conductive fibres — typically carbon-loaded or metallic — to dissipate charge as cleaning proceeds. If your cleanroom is also an EPA, as is common in electronics assembly environments, specify ESD-safe wipers throughout.
Phil Industries stocks cleanroom wipers for ISO Class 5 through Class 8, including dry and IPA-saturated polyester and ESD-safe variants, available for same-week delivery from our Ubi warehouse. Browse our cleanroom wiper range or request a sample.
