The Society of International sustaining growth for Antimicrobial Articles

3. Antibacterial Power Sustainability Test Methods for Antibacterial Products(2012 Version)(1) Waterproofing Test
1. Outline
An antibacterial product conferred with an antibacterial function (hereinafter simply referred to as a
product) can lose antibacterial power due to a loss of its antibacterial ingredients from its surface when incontact with water (or warm water). With this in mind, an accelerated test is performed under test
conditions (water temperature and immersion time) specified for each product category to prepare test
pieces1. Using these test pieces, an antibacterial power test is performed to evaluate the sustainability of
the antibacterial power (waterproofing performance) of the product.
2. Procurement of Supplies
The following instrumentation and equipment shall be provided. The reagents, instruments and othersupplies used in this test method shall be in conformity with the Japan Industrial Standards or the JapanesePharmacopoeia unless otherwise specified.
In addition to the items shown below, instruments etc. shall be provided as required.
(1) Desiccator(2) Measuring cylinders(3) Immersion containers (shall be made of glass, polyethylene or polypropylene, and may have an
optionally chosen shape and capacity; shall be thoroughly cleaned before use2.)(4) Dryer (air bath)(5) Deionized water or distilled water(6) Heater(7) Others
3. Preparation of Test Pieces
The test piece subjected to this test shall, as a rule, be an actual supply of the product as is. However,provided that it is prepared using the same method of treatment, and is judged to produce similar levels ofantibacterial power even if it has a different shape from that of the product,3 it may be used as the test
piece.
The test piece may be cut to desired size after a waterproofing test is performed or prior to awaterproofing test. Described below is how to prepare a test piece previously cut to a size suitable forthe antibacterial power test.

1

The test piece subjected to the antibacterial power test of an antibacterial product must, as a rule, be a test pieceobtained by this method of preparation.
2
As clean containers as possible shall be used. It is desirable that dedicated immersion containers be used for
untreated test pieces and antibacterial test pieces, respectively.
3
Should this test method be difficult to apply to prepare a test piece due to a special shape of the product and the like, asample prepared by another method of treatment deemed to produce nearly the same results for antibacterial power
may be used as the test sample. If a non-actual supply of the product is used as the test sample, however, the fact
shall be stated in the Test Results section.

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The Society of International sustaining growth for Antimicrobial Articles(1) Provide twelve test pieces cut into 502 mm square (thickness not more than 10 mm) standard pieces
and use these as the antibacterial test pieces1.
(2) Provide six untreated samples, previously cut into the same size as the test pieces, and use these as
the untreated test pieces2.
4. Test Procedures
Proceed as directed below.
(1) Place the specified amount (20.4 ml per cm2 of antibacterial treatment area of test piece) of
deionized water or distilled water in an immersion container and maintain a temperature in the range
specified for the product category of the test piece. The water temperature shall be determined withreference to the four categories by intended use of product shown in Table 1 3.
(2) Place the test piece in the container to completely immerse the entire test piece in the deionized wateror distilled water and allow to stand for the specified time4. In the case of warming, wait until the
specified water temperature is reached, and then place the test piece in the immersion container.
(3) After 16 hours of immersion, remove the test piece, drain the water on the test surface, andimmediately perform the antibacterial power test. If the antibacterial power test cannot immediately
be performed, keep the test piece in a dry state in a desiccator or dryer (air bath) 5. If impossible,
the test piece may be kept in a container that does not influence its quality, such as a glass Petri dish.

1

The thickness of the test piece shall be up to 10 mm to allow easy entry into a Petri dish. If the thickness exceeds 10mm, the test piece shall be sliced to obtain a thickness of less than 10 mm. In this case, be sure to reserve theoriginal surface of the test piece, and to perform the test on the reserved surface. Regarding the size of the test piece,
the test piece may be rectangular, provided that its area is constant. However, the test piece size should not be lessthan a quarter of the original area. If a standard test piece area cannot be assured because of the size of the test pieceand the like, the size of the test piece shall be indicated.
In the antibacterial power test after preparation of the test pieces, use three test pieces (6 in total) for each of thebacteria Staphylococcus aureus NBRC12732 (ATCC 6538P) and Escherichia coli NBRC3972 (ATCC 8739).
2
An untreated sample refers to a product not undergoing antibacterial treatment, and must be prepared with the samematerial using the same method of treatment as those for the test pieces.
3
The category applied in the waterproofing test shall be indicated. If the test is performed under test conditions(water temperature and immersion time) other than those categorized in Table 1, the fact and the test conditions usedshall be indicated.
4
The immersion need not always be continuous, as long as the immersion time reaches the specified level on a
cumulative basis. If more than one test piece is placed in the same container, they shall be placed with theirantibacterial power test surfaces without overlapping, while keeping a sufficient gap to avoid the contact of theantibacterial power test surfaces with the inside wall of the container and contact with the other test pieces. However,an antibacterial test piece and an untreated test piece must not be placed in the same container. The test pieces shall,
as a rule, be allowed to stand, with no stirring, shaking and the like, but stirring, shaking and the like may be
performed if judged to be necessary for the sake of test convenience.
5
The temperature range shall be between 30 and 40C.

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The Society of International sustaining growth for Antimicrobial Articles

5. Standard Test Conditions and Categories
The following two standard conditions for the waterproofing test shall be established.
(1) Immersion temperature1(2) Immersion time
Regarding product categorization for the waterproofing test, intended uses of products are divided into
four categories in view of the degree of contact of product and water. Relationships between the
categories and immersion temperature and time are shown in Table 1.
Table 1

Product categories for waterproofing test and immersion temperature and time

Category0

Immersion conditions
Water temperature
Immersion time
(hr)
(C)

Products that do not come into contact withwater
(products that do not come into contact withwater in ordinary use settings, or come into
contact with water only during cleaning etc.)
Products that are unlikely to come into contact
with water(products that do not come into contact withwater except for incidental splashing)
Products that often come into contact with water(products for containing water or for use inwater)
Products that often come into contact with warm
water
(products for containing warm water or for use
in warm water)

Not performed

1

Normal temperature2

16

2

505

16

3

905

16

Applicability (range)

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The Society of Industrial Technology for Antimicrobial Articles

1

The test may be performed under severer conditions than those specified for the category of the product shown in
Table 1. Specifically, the test may take place at a higher temperature and for a longer immersion time than thosespecified for the category of the product. In the case of a test piece to which the antibacterial power test is difficult
due to deformation etc. under the temperature conditions specified for the category 3 of the product (thermoplastic
resins that do not endure 90C heat, etc.), the temperature conditions may be set at lower levels that do not cause suchdeformation. In this case, however, the immersion time shall be doubled per 10C of temperature reduction.
2
Normal temperature is 5 to 35C (JIS Z 8703). Temperature shall be set in view of the intended use of the product.
However, temperature controls are unessential.

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