The Laundry Process
How SterilTex Washes
Reaching ISO 3 cleanliness in a cleanroom laundry process isn’t about washing harder — it’s about making sure a garment never re-enters open room air at any point between the wash cycle and the sealed bag it ships in. This is what a fully validated cleanroom garment washing process looks like, stage by stage: the same barrier-washer platform and controlled-air chain that let SterilTex hold an ISO 3 classification under ISO 14644-1, not just claim one. Here’s how the Exdron WashPro3 turns that standard into a repeatable, documented cleanroom decontamination process — engineered to strip particulate and microbial contamination out at every stage of the ISO 3 cleanroom laundry process, rather than leaving a single wash cycle to do all the work.
- Incoming inspection and repair — the first stage of the cleanroom garment washing process. Every soiled garment entering SterilTex’s cleanroom laundry is scanned into the tracking system and 100% inspected on a lit inspection table before it ever reaches the wash, so contamination hotspots and physical damage are caught early in the cleanroom garment inspection process rather than discovered later. Garments flagged for repair go through a dedicated, documented repair station first, extending garment life and ensuring only sound, cleanroom-ready garments proceed into the barrier washer. Each garment keeps its own identity through the entire cleanroom laundry process, so nothing is processed, tracked, or returned by guesswork.
- Soil classification and batch-lot sorting for the ISO 3 cleanroom wash. Once inspected, garments are separated into batch lots by soil classification instead of being washed as one undifferentiated load. A lightly-soiled batch and a heavily-contaminated one don’t get the same water volume, chemistry or cycle time — sorting first means every batch in the ISO 3 cleanroom laundry process gets exactly the program it needs, rather than a one-size-fits-all wash.
- Physical clean/dirty separation — the barrier at the heart of the cleanroom decontamination process. Soiled garments enter through the dirty-side door, where the barrier does its first job: the washer is built into a sealed partition wall with 2 independent, interlocked doors, so contaminated linen never shares air with finished, ISO-classified garments. Batches move through the barrier washer in a single, linear direction — dirty side in, clean side out — so a garment can never travel backward across the barrier once it has entered the cleanroom laundry cycle. This dirty-to-clean separation is the backbone of any genuine cleanroom decontamination process, enforced by the equipment itself and not left to procedure or floor markings. An intelligent weighing system reads the actual load and optimises water, chemistry and energy to that exact weight, eliminating wasted resources and under- or over-dosing.
- Ultrapure water rinsing for particle control in cleanroom garment washing. 2 independent inlets feed the drum multi-stage deionised water, treated to the highest-purity grade used in ultra-clean manufacturing and measured by resistivity in the multi-megohm range, on every single cycle — never ordinary mains water, and never only when a specific program calls for it. Hard-water minerals and dissolved solids are themselves particulate contaminants, so the rinse water used in this cleanroom garment washing process must deposit nothing behind; that level of purity is what makes real particle control possible and allows garments to leave with an ultra-low residual particle count.
- Precise chemical dosing for cleanroom-grade decontamination. Up to 8 programmable channels inject detergents, neutralisers and — where required — disinfectant or sporicidal agents at exactly the right stage, temperature and concentration. This is where microbial contamination control is built into the cleanroom laundry process at the chemistry level, not bolted on afterward — everything is dosed automatically by the program, removing human variability from the cleaning process.
- Thermal and/or chemical disinfection for ISO 14644-1 compliant garments. Electric or dual electric-plus-steam heating (18 kW) holds precise disinfection temperatures for validated hold times. Temperature is the workhorse of microbial reduction; combined with chemistry it delivers the log-reduction that sterile and aseptic-area cleanroom garments require. Every temperature and hold time is recorded as part of SterilTex’s validated cleanroom decontamination process.
- High-G extraction to protect cleanroom garment integrity. At 1,000 RPM and a 350 G extraction factor, the machine drives out water — and with it, dislodged particulates and chemical residue — with extreme efficiency. Better extraction also shortens the drying stage that follows, protecting the garment’s fibres and conductive grid and preserving the garment integrity that an ISO 3 cleanroom laundry process depends on.
- Transfer through the barrier to the clean side of the cleanroom laundry facility. The clean-side door opens only into the controlled clean zone of the cleanroom laundry facility. An optional second screen lets the clean-side operator confirm the cycle completed correctly before the garment is touched — a documented checkpoint before it ever leaves the barrier washer.
- Controlled-air processing chain — the ISO cascade that actually delivers ISO 3. This is where ISO 3 cleanroom classification is actually won — and it’s the stage most laundries skip. Drying, inspection, folding and packing all take place inside progressively cleaner controlled-air zones rather than open room air, so the garment is never re-exposed to ordinary air between the wash and the bag. It’s this final stretch of the cleanroom garment washing process — not the wash cycle itself — that determines whether a laundry can actually hold an ISO 3 rating under ISO 14644-1.
- Garment integrity control to maintain ISO 3 cleanroom compliance. Every garment is checked for particle-shedding through automated Helmke-drum (or equivalent) testing, alongside controlled fabric selection and scheduled retirement. A cleanroom laundry can test at ISO 3, but if a degraded garment is still shedding fibres, the classification means little — so any garment whose fibres or conductive grid have begun to degrade is pulled before it can ever fail inside your cleanroom. Results are logged into a statistical process control (SPC) system, with regular charting across every critical stage of the cleanroom garment washing process, so garment performance is tracked as a trend rather than a one-off pass/fail snapshot — using industry-standard microscopic particle and fibre testing methods (e.g. ASTM F51).
- A cleanroom laundry facility built for ISO 3 and above. SterilTex’s cleanroom laundry facility is built and validated to reach ISO 3 — our ceiling classification — and the same barrier-washer platform and controlled-air chain also cover every classification above it, from ISO 4 through the ISO 5–8 general controlled workwear that covers most pharmaceutical and medtech support areas. Every cycle runs on the same highest-purity water grade used in ultra-clean manufacturing, regardless of which ISO classification a client’s cleanroom carries, because dissolved minerals are contaminants at any classification we serve. A client running an ISO 3 aseptic line and a client running an ISO 5 general controlled area each get a cleanroom washing program engineered for their specific room, backed by the same water quality and the same controlled-air cascade throughout.
- Precise about which standard a number belongs to in the ISO 3 cleanroom laundry process. “ISO 1” or “ISO 100” language inherited from the retired U.S. Federal Standard 209E doesn’t translate one-to-one onto ISO 14644-1 classes, and the two get blurred together more often than they should across the cleanroom laundry industry. At SterilTex, every classification we quote — for the garment, the wash program, or the facility — states clearly which standard it’s measured against, so a number on our documentation means exactly what it says, and a client comparing our cleanroom laundry service to any other option is comparing the same scale.
At SterilTex, quality control in the cleanroom garment washing process isn’t a single checkpoint bolted onto a finished wash — it runs at every stage of the ISO 3 cleanroom laundry process, from the lit inspection table at intake through the final integrity check at the end of the line, so problems are caught inline rather than downstream. That’s the difference between a cleanroom laundry service that tests clean once and one that’s engineered to stay clean, cycle after cycle.
Logistics & Delivery
A cleanroom laundry service is only as good as the logistics behind it