5.1 Current solid surface test methodologies, such as the Test Method E2180 and ISO 22196, do not take into account the complexities associated with a ceramic surface. This includes, but is not limited to, differing chemistries incorporated into the glaze and desiccation due to water absorption through the bisque body. Each point will be elaborated below:

5.1.1 The glaze composition of ceramic tiles can vary between manufacturers, lots, and product lines. Some glaze chemistries such as tin, silver and copper can negatively impact the testing conditions. Therefore, an untreated tile from the same lot is not always suitable for comparison. The control tile proposed herein is capable of supporting growth over the indicated time frame and nutrient level (see Section 9).

5.1.2 Desiccation is a common problem when testing tile surfaces. This can be overcome by pre-hydrating the tile by placing the specimen on a moistened wipe and allowing incubation for 18 to 24 h before beginning the test. This reduces the number of false positive results and more accurately measures the ability of the antimicrobial to inhibit growth.

5.2 This test method utilizes a low inoculum load and requires growth on the control substrate to demonstrate a valid testing environment. In addition, while some antimicrobials demonstrate activity against static cultures, others require growth of the bacteria to maintain activity. A low inoculum level will allow for both types of antimicrobials to be examined with the same testing conditions.