Test method
ISO 20645 antibacterial textile testing
ISO 20645 determines the antibacterial activity of flat textile fabrics by agar diffusion. A specimen is placed on inoculated agar and the plate is read for the zone of inhibition around the specimen and for growth underneath it — a qualitative read, not a percentage.
- Result
- Zone of inhibition, and growth underneathA qualitative read, not a percentage
- Suits
- Woven, knitted and other flat textiles
- Use it as
- A fast, inexpensive screenAATCC 100 or JIS L 1902 when the claim needs a number
- Turnaround
- 14–30 daysDate confirmed before you ship
The test in four steps
Drawn as a schematic, not photographed at our bench. The drawings show the sequence; the conditions are the standard's.
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Treated and control
Treated fabric and, where possible, the same fabric untreated as a control.
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On inoculated agar
A specimen is placed on inoculated agar.
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Read the zone
The plate is read for a zone of inhibition around the specimen. A bound finish may show none and still work.
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Read underneath
Growth under the specimen is read too, against the untreated control.
Solid green outline: treated. Dashed gray outline: untreated control. Green dots: the organisms.
What the test involves
Because it reads a zone rather than a count, ISO 20645 is fast and inexpensive, and it is the method to reach for when you want to know whether a finish is doing anything at all before you pay for a quantitative test. It suits woven, knitted and other flat textiles.
A leaching finish produces a clear zone; a bound, non-leaching finish may show no zone at all while still working. That is not a failure of the fabric, it is a limit of the method — and it is the reason a bound finish usually needs AATCC 100 or JIS L 1902 instead.
We run ISO 20645 in our BSL-2 laboratory in Bandung, certified annually by the International Antimicrobial Council (USA) and participating in AATCC's PTP4 antibacterial proficiency program.
What you receive
- An independent test report in IAC or AATCC format
- The rating or observation the standard defines, against the untreated control
- A certificate your customers, auditors, and procurement teams can verify
Common questions
Is ISO 20645 enough on its own for a buyer's claim?
Sometimes, if the specification names it. Many buyers want a number, and a zone is not a number — in that case ISO 20645 is the screen and AATCC 100 or JIS L 1902 is the test that supports the claim.
My fabric showed no zone. Does that mean the finish failed?
Not necessarily. A finish that binds to the fibre and does not migrate into the agar can read as no zone while still reducing bacteria on contact. Tell us which chemistry was used and we'll advise whether a quantitative method is the right next step.
What samples do I send?
Treated fabric and, where possible, the same fabric untreated as a control. We'll confirm sizes and quantities when you book.
How long does it take?
14–30 days, depending on the method and the current queue in the lab. We confirm the date when we accept the sample, before you ship anything.
Related methods
Not sure which one your buyer wants? Send us the specification and we will read it with you before any sample ships.
Book an ISO 20645 test
Send us the fabric and the finish. We'll confirm whether the agar diffusion test answers your question, or whether you need a quantitative method.