Gypsum board in 1980s: Moisture boards · 479

Gypsum board (CaSO4·2H2O + paper faces) is a family of grades whose density ~700–1000 kg/m³, heat band calcines ~80–180 °C (dehydration), and fire letter A2-s1,d0 typical; core A1. Gypsum board is sold as grades, not as a single substance. Chemistry CaSO4·2H2O + paper faces, density ~700–1000 kg/m³, heat band calcines ~80–180 °C (dehydration).

This atlas treats Gypsum board as a system: mill route, coatings, tests and the cavity it sits in. Conductivity note: ~0.17 W/m·K. Insulation score 34/100 is relative to 32 entries — metals lose, VIPs and aerogels win. Fire letter in editorial use: A2-s1,d0 typical; core A1. Do not equate A1 with “safe in a blaze” or E with “illegal”. Assemblies decide.

Origin: Sackett 1894; US Gypsum 1916, United States. The process chapter follows feedstock → conversion → forming → finish → install. Uses span buildings to defence / safety. Pairings matter: mineral-wool. Circularity mark 62/100. Ask which scrap, which certificate, which year. Related atlas entries, a short glossary, and three threads that keep Gypsum board honest.