How to Repair Auto Body Parts Without Warpage

How to Repair Auto Body Parts Without Warpage

Auto body panels are typically constructed of very thin, lightweight steel.  Mercedes Benz, for example, installs auto body panels that are .8 mm thick (about the thickness of two sheets of notebook paper) and MIG welding these delicate parts without warpage can be difficult without the proper tools.  For this reason, many auto body shops opt to “Bondo” damaged auto body parts rather than risk damaging the parent metal.   Fortunately, Super Alloy 1 can make steel auto body repairs quickly and easily, without the risk of overheating the steel parts.

In this video, we utilize 350°F Super Alloy 1 and an oxyacetylene torch (a propane torch would be just as effective for this low temperature application) to repair a hole in a steel door panel.  This unique multi-metal solder will repair the fender at such a low temperature that even the paint around the hole is not affected.  (If potential heat damage is a concern, apply Heat Freeze Heat Paste around the repair area prior to soldering)

Begin by pre-cleaning the steel body panel with a wire brush to remove any oxidation.  Dip the rod into the liquid flux and apply the flux to the repair area.  Be sure to broadly heat the parent metal to gradually bring the part to the 350°F working temperature.  The non-corrosive flux acts as a temperature guide, changing color from honey to root beer brown to indicate it’s time to apply the rod.  Continue to flow the rod by broadly heating the parent metal and add more flux if necessary to smooth the solder.

After soldering, remove any excess flux with warm water and a wire brush.  The part can then be polished and painted, with no noticeable difference between the original steel and the Super Alloy 1 filler rod.



  • Broadly heat the base metal when working with Super Alloy 1
  • Super Alloy 1 can be used with propane, butane, MAPP gas, acetylene, oxyacetylene
  • Always remember to turn the oxygen down with oxyacetylene
  • For added warpage protection, combine with Heat Freeze Heat Paste


NotePlease observe all AWS Safety & Health Guidelines when using Muggy Weld products.