Some times a dent can be so severe or deep that we say the metal gets stretched or locked up. When you try to lift up the damaged area the depth of the dent stays the same and the area surrounding the dent rises. Another scenario is when you push the dent up it falls back down. We call this oil canning and it's a tell tale sign of stretched metal or aluminum. To repair this damage you need to have patience, skills and proper tools.
Enter Electro magnetic paintless dent repair tools. These machines heat up and move metal and aluminum at the molecular level. Using these tools in conjunction with pushing techniques allows a experienced technician to get the metal moving. It will tighten up and bring the substrate back to its original position and strength.
The photo that goes with this post is of a Mercedes Benz CLA. The aluminum hood sustained a hard impact that resulted in a very deep stretched dent right next to the body line. Pushing techniques alone would not budge the center of this dent. The Aluminum T-Hotbox was used as a big part of this repair along with very sharp tip tools. In the end the dent was repaired to a very high quality and the factory paint was saved on this Mercedes.