Which material ultimately provided the first truly practical incandescent lamp filament lasting over 1,200 hours?

Answer

Carbonized bamboo fiber.

The sustained breakthrough came when Edison's laboratory successfully treated and carbonized strips of bamboo fiber, achieving a lifespan exceeding 1,200 hours.

Which material ultimately provided the first truly practical incandescent lamp filament lasting over 1,200 hours?
inventionbulbelectricityEdisonfilament