Metal Inert < Or Active> Gas A welding process and machine which incorporates a wire feed electrode and an inert gas shield. MIG welding Is an extremely useful and probably the simplest form of welding to learn. The inert gas used in MIG welding is, typically a 25/75% mix of Argon and CO2 The electrode is fed out through the center of the "gun" or "stinger" at a controlled rate and the temperature of the weld is usually controlled by a knob or dial on the welder itself. MIG welding is the workhorse of most Scenic shops that employ the use of Steel in their construction process. MIG can be used to weld aluminum with the proper setup.