The video “Auto Body Repair 101 (Understanding the Basics)” was prepared by Auto Body Training Solutions, a small company whose business is training auto body repair technicians. Rather than classroom instruction, they teach frame, unibody, and sheet metal repairs to technicians at the work locations of their auto body service providers.
One problem with auto body service today is the belief that techniques used in the 1940s and 1950s no longer apply to today's vehicles, but they do, especially when dealing with work hardening.
Work hardening occurs when an accident bends or creases sheet metal because the underlying structure of the sheet metal changes. Where bends occur, the metal along the outside of the bend gets stretched while the metal on the inside of the bend gets compressed.
Once work hardening occurs, returning the sheet metal to its previous form is complex, and technicians often find a bump that remains at the spot of the bend after straightening the metal.
Unfortunately, you cannot eliminate work hardness but can make it worse. Technicians often use a hammer and dolly to pound out the dents, only to find that a bump remains. Auto Body Training Solutions has other approaches to fix these problems, and they start with choosing the proper tools to fix the dent, as shown in other videos.