What material was commonly used as insulation or fire retardant before 1977?

Asbestos was widely used as insulation and fire retardant before 1977 due to its remarkable properties, including resistance to heat, fire, and chemical damage. Its unique fibrous characteristics allowed it to be woven into various materials, providing not only thermal insulation but also soundproofing capabilities.

In many construction and manufacturing contexts, asbestos was favored for these qualities, making it a popular choice for insulation in buildings, pipe coverings, and fireproofing materials. However, it became clear over time that exposure to asbestos fibers posed serious health risks, including lung diseases such as asbestosis and mesothelioma, leading to its ban in many countries after 1977.

The other materials listed—fiberglass, wood shavings, and mineral wool—do not have the same historical significance or widespread use as asbestos for these particular applications before 1977. Fiberglass was developed as an alternative and gained popularity after the dangers of asbestos became known. Wood shavings were used in various applications, but not as a primary fire retardant or insulation material in the same sense. Mineral wool, while also used for insulation, did not have the extensive use and problematic health issues associated with asbestos before its decline in use.