Prior to this time, body lead was required to fill small imperfections in sheet metal. The lead was sold in 1-pound bars, 20 bars to a box. It was heated and turned into a molten form, then worked into a fender or other sheet metal panel with a wooden spoon. It worked pretty well. But by about 1955, health and environmental issues raised with the use of lead spelled its demise.
A Mr. J.C. O’Donnell invented body filler in 1955, but it would take another year before it was referred to as plastic body filler. Next to the development in 1956 of acrylic lacquer by DuPont Company and Rinshed-Mason, plastic body filler was one of the most profound developments of the collision repair world in the ‘50s. It didn’t take long before many simply referred to all plastic fillers by one of its most popular trade names: bondo. Plastic fillers were easier to use, enabling the shop to make a cheap and fast repair. The problem was, however, that early plastic fillers sometimes fell off the car, prompting either a redo of the repair or a very angry customer---or both. O’Donnell went on to found the Unican company on July 31, 1962, which is well-known for its variety of body filler products.
By the mid-1950s, the collision repair industry as we know it today was in full swing.