To get the exact details of the process and product used, it would probably be better to ask them directly .
but as far as I understand :
- First the panels spot welds are drilled to expose the panel seams or to remove the panel completely.
- They grind(sand blast for the front panel) cut and reweld panel where necessary to remove all the rust .
- Once the rust is out of the panel, it gets rust converted to make sure everything is completely gone .
- The panel is then primed and welded back in place .
- Once all panels got cleaned and back on the car, the shell was pumped with an epoxy coating until it oozed out of every seams to make sure all the panels inner are covered and sealed .
- seam sealant is then applied and the shell sent for paint .