What is the minimum allowable radius of the test cap used in SFRM bond strength testing?

In the context of Spray-Applied Fire-Resistive Materials (SFRM) bond strength testing, the minimum allowable radius of the test cap is established to ensure consistent and reliable test results. A radius of 1 inch is specified as it strikes a balance between practical usability and the ability to create a uniform bond strength test.

Using a 1-inch radius cap allows the test to focus on a sufficient area of the SFRM application, which helps in obtaining an accurate measure of the bond strength against the substrate. This size is also manageable for application and removal during testing while ensuring that the test sample is large enough to provide a meaningful representation of the material's performance.

Smaller radii might not capture the bonding characteristics accurately or could lead to localized failures that do not reflect the overall performance of the application. Thus, the specification of a 1-inch radius is a critical component of ensuring that the testing methodology complies with industry standards for assessing the quality and effectiveness of fireproofing applications.