Phase-change material in 1948: Telkes Dover house · 579

Phase-change material (paraffins / salt hydrates / bio-waxes) is a family of grades whose density ~0.8–1.6 g/cm³, heat band designed 18–28 °C for buildings, and fire letter paraffin = combustible; salts vary. Phase-change material is sold as grades, not as a single substance. Chemistry paraffins / salt hydrates / bio-waxes, density ~0.8–1.6 g/cm³, heat band designed 18–28 °C for buildings.

This atlas treats Phase-change material as a system: mill route, coatings, tests and the cavity it sits in. Conductivity note: low-to-moderate; often needs fins or graphite. Insulation score 52/100 is relative to 32 entries — metals lose, VIPs and aerogels win. Fire letter in editorial use: paraffin = combustible; salts vary. Do not equate A1 with “safe in a blaze” or E with “illegal”. Assemblies decide.

Origin: NASA / Telkes 1940s–70s; building PCM 2000s, United States / Germany. The process chapter follows feedstock → conversion → forming → finish → install. Uses span buildings to defence / safety. Pairings matter: mineral-wool. Circularity mark 48/100. Ask which scrap, which certificate, which year.