The ASTM C661-15 (2022) standard specifies a test method for the determination of resilience sealant indentation hardness using a hardness gauge (Shore hardness tester). This method is suitable for evaluating the hardness performance of resilience sealing materials, especially in construction and industrial sealing applications. The hardness value of the sealant surface is measured by indentation of the sealant surface using a hardness gauge by applying a certain pressure under standard conditions. This standard covers the test operation steps, instrument requirements, test environmental conditions, and the representation of the results, ensuring that the test results are comparable and in conformity. Through this test method, the suitability of the sealant and its long-term performance can be effectively judged.