AATCC 100 vs JIS L 1902: which antimicrobial test does your buyer expect?

The short answer

Ask your buyer. In practice the market decides this, not the chemistry: US apparel brands name AATCC 100, Japanese buyers and Japanese-market retailers name JIS L 1902, and European buyers will often accept the agar-diffusion screen ISO 20645 instead of either. If a specification already names a method, that is the method — the rest of this note is about what to do when nobody has named one, and about why the two reports do not read the same way.

What each one actually measures

AATCC 100 is the American standard for antibacterial finishes on textile materials. Swatches are inoculated with the test organisms, held in contact with the material for a defined period, and the surviving organisms are recovered and counted. The result is expressed as a percentage reduction against the untreated control.

JIS L 1902 is the Japanese Industrial Standard for antibacterial activity on textile products. It carries a quantitative route that also inoculates, incubates and counts, and a qualitative route that reads growth on an agar plate. The quantitative route reports an antibacterial activity value calculated against the control rather than a bare percentage.

Both are count-based. Both need an untreated control. The difference that matters commercially is the last sentence of each paragraph: one hands you a percentage and the other hands you an activity value, and a buyer who asked for one will not usually accept the other's number without a conversation.

Where people lose money

Three failure modes, in the order we see them.

1. Testing before the specification arrives. A mill runs AATCC 100 because it is the method it has heard of, then the buyer's technical pack asks for JIS L 1902 and the whole test is repeated. Ask for the specification first; it costs one email.
2. No control sample. Every quantitative method compares the treated material against the same material untreated. Without the control there is nothing to reduce from, and the test cannot be reported. Send both.
3. Testing the wrong stage. A finish that survives the lab does not always survive the wash cycles the claim implies. If the claim is durability, the test has to be run on material that has been through the washes — decide that before the sample is cut, not after the first report comes back.

A decision you can make in one minute

• The buyer named a method → run that method.
• The buyer is American and has not named one → AATCC 100.
• The buyer is Japanese and has not named one → JIS L 1902.
• You want to know whether the finish is doing anything at all, before you spend on a quantitative test → ISO 20645, the agar diffusion screen.
• The product is not a textile → the ASTM family, starting at ASTM E3160.

If none of those fits, send us the specification and the fabric and we will read it with you. We would rather redirect you before a sample ships than after.