ASTM International founded in 1898, formerly known as American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services. Some 13,000 standards are searchable on their web site and the specific standards detailed on our data sheets are ASTM-D5470 for thermal conductivity, ASTM-D2240 for hardness and ASTM-D149 for breakdown voltage.