ASTM D4300-01(2008)

These test methods are designed to be used to determine the susceptibility of the adhesive film to biodegradation and whether the adhesive will carry into the bond line sufficient anti-fungal properties to prevent growth of fungi frequently present on the gluing equipment, on adherends, or in the adhesive as applied.

Potato dextrose agar (PDA) provides a complete medium for the growth of fungi, while mineral salts agar (MSA) lacks a carbohydrate source and provides a less favorable medium. Use of PDA tests the adhesive film for its ability to resist the growth of fungi on its surface as well as its ability to repel a copious growth of fungi on the adjacent agar surface. Use of MSA tests the adhesive film primarily for its ability to resist the growth of fungi on its surface. When it is used, there is a reduced possibility that the growth from the agar will be mis-read as coming from the adhesive film, since fungal growth on the adjacent agar will be scant.

Note 2—The method given here using the MSA is based on Practice G 21, adapted to be used with adhesives. Requirements to meet the approval of government specifications are the use of the MSA described in 10.2, and a mixed species of fungi described in 8.2 for the inoculum.

The results obtained when using the procedures given in this method apply only to the species used for the testing. The test species listed in Section 8 are frequently used by laboratories to test for antifungal properties, but they are not the only ones which could be used. Selection of the fungal species to test against requires informed judgment by the testing laboratory or by the party requesting the tests. These methods are especially useful when species that have been isolated from contaminated adhesives are used as the test species (see Section 8) to aid in the selection of more effective fungicides.

The efficacy of some biocides may change in storage due to the chemical and thermal environment to which they are subjected as components of certain adhesives. These test methods are not appropriate for determining the effect of fungal contamination on adhesives under water-soaking conditions, because they are not designed to cover the possibility of water-soluble biocides leaching out of the bond line.

These test methods are dependent upon the physiological action of living microorganisms under a reported set of conditions. Conclusions about the resistance of the test adhesive to fungal attack can be drawn by comparing the results to simultaneously run controls of known resistance. See X5.2 for statements regarding test repeatability.

1.1 These test methods test the ability of adhesive films to inhibit or support the growth of selected fungal species growing on agar plates by providing means of testing the films on two agar substrates, one which promotes microbial growth, and one which does not.

1.2 These test methods are not appropriate for all adhesives. The activity of certain biocides may not be demonstrated by these test methods as a result of irreversible reaction with some of the medium constituents.

Note 1—As an example, quaternary ammonium compounds are inactivated by agar.

1.3 A test method is included for use with low-viscosity adhesives along with an alternative method for use with mastic-type adhesives. Also, a method approved by the government is given.

1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. These test methods are designed to be used by persons trained in correct microbiological techniques. Specific precautionary statements are given in Section 7 and in 14.3.2.