The Society of International sustaining growth for Antimicrobial Articles

3. Antibacterial Power Sustainability Test Methods for Antibacterial Products(2012 Version)(2) Light Fastness Test
1. Outline
An antibacterial product conferred with an antibacterial function (hereinafter simply referred to as aproduct) can lose antibacterial power due to degeneration or deterioration of the antibacterial ingredientson its surface when exposed to light (particularly ultraviolet rays). With this in mind, an accelerated test
is performed under exposure conditions specified for each product category to prepare a test piece1.
Using the prepared test piece, an antibacterial power test is performed to evaluate the sustainability of theantibacterial 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) Light fastness tester2 (xenon arc lamp type tester JIS B 7754 or Sunshine carbon arc lamp type, JIS B
7753 compliant)(2) Desiccator(3) Dryer (air bath)(4) Others
3. Preparation of Test Pieces
The test piece3 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, it may be used as the test piece.
The test piece may be cut to the desired size either after or prior to a light fastness test. Described below
is how to prepare a test piece previously cut into a size suitable for the antibacterial power test.
(1) Provide six test pieces cut into 502 mm square (thickness not more than 10 mm) standard pieces anduse these as the antibacterial test pieces4.

1

The test piece subjected to the antibacterial power test of an antibacterial product shall, as a rule, be a test pieceobtained by this test method.
2
The name of the light fastness tester used shall be specified in the Test Results section.
3
Provided that this test method is difficult to apply to prepare a test piece due to a special shape of the product and thelike, a sample 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 piece, however, thefact shall be stated in the Test Results section.
4The 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 this 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 beless than a quarter of the original area. If a standard test piece area cannot be assured because of the size of the test
piece and the like, the size of the test piece shall be indicated. In the antibacterial power test after preparation of thetest pieces, use three test pieces (6 in total) for each of the bacteria Staphylococcus aureus NBRC 12732 (ATCC6538P) and Escherichia coli NBRC 3972 (ATCC 8739).

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The Society of International sustaining growth for Antimicrobial Articles(2) Provide twelve untreated samples, previously cut to the same size as the test pieces, and use these as
the untreated test pieces1.
4. Test Procedures
Proceed as directed below.
The operating conditions for the light fastness tester shall be established according to the intended use ofthe product with reference to the three categories shown in Table 2 2.
(1) Attach the sample holder with the test piece on to the sample rotation frame3.
(2) Operate the apparatus under the conditions specified for the product for the test piece, and irradiate
light for the specified time4.
(3) When the cumulative exposure time has reached the time specified for the product, remove the testpiece. If the test piece surface is wet, drain and allow to stand for 1 hour or more, then immediately
perform the antibacterial power test.
If the antibacterial power test cannot be performed immediately, keep the test piece in dry state in adesiccator or dryer (air bath) 5. If it is impossible, the test piece may be kept in a container that
does not influence its quality, such as a glass Petri dish.

1

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 piece.
2
The test may be performed for a category higher than the category specified for the product shown in the table. If
the test is performed under conditions other than those for the category for the product, the conditions may involve
higher energy and longer exposure time than the test conditions specified for the category of the product. Thecategory applied in the light fastness test shall be indicated.
If the test is performed under test conditions (lightsource and irradiation time) other than those categorized in Table 2, the fact and the test conditions used shall beindicated.
3
Set the test piece so that the antibacterial power test surface is the surface to be irradiated, being careful to avoid using
the wrong side. Do not change the position of the test piece sample holder.
4This test method, unlike a weatherbility test, does not always require a step for water spraying. The temperature
range setting for the black panel thermometer shall be between 50 and 70C (633C chosen for reference) in view ofthermal deterioration that can affect test results.
5The temperature range shall be between 30 and 40C.

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5. Standard Test Conditions and Categories
The following two standard conditions for the product specifications for the light fastness test shall beestablished.
(1) Tester model name (light source conditions etc.)(2) Exposure time (hr)Regarding product categorization for the light fastness test, intended uses of products are divided into
three categories in view of the degree of light exposure to the product. The categories and exposure
conditions are shown in Table 2.
Table 2

Product categories for light fastness test and exposure conditions

CategoryExposure time (hr) by type of tester
Xenon
Direct sunlight(60w/m2)

0Not performed

1108

2

10080

Applicability (range)
Products that do not require consideration ofoccasions of light exposure(disposable products etc.)
Products unlikely to be used under light(products for indoor use etc.)
Products often exposed to light(products for constant outdoor use, lighting
appliances, etc.)

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