08-24-2012, 09:52 AM
Elijah is right. It is somewhat similar to oxy-fuel welding in that one hand controls the torch and the other hand controls the filler rod. The big difference there is, an oxy-fuel torch doesn't act like a huge filler rod magnet and destroy your torch tip if they touch! (Ask me how I know..) 
Just kidding....
However - accidentally touching the tungsten electrode with any other material (filler rod, work piece, grease, oil, etc.) will contaminate the tip and cause all kinds of problems with trying to maintain a good welding arc.
MIG lays down a lot of weld metal, and does it fast - but with some spatter.
TIG is slower, having to feed the filler materiel by hand. But it is much more refined and controllable, and capable of maintaining a very low amperage arc. That allows you to pinpoint the arc, and reduce the HAZ (heat affected zone) of your weld bead. If you get showered with ANY sparks from TIG, you are doing it wrong...
TIG is also more expensive over all, considering the equipment and consumables costs. If you are building a structure go MIG. If you want to attach two sheets of aluminum foil together for the space shuttle go TIG.
Just kidding....
However - accidentally touching the tungsten electrode with any other material (filler rod, work piece, grease, oil, etc.) will contaminate the tip and cause all kinds of problems with trying to maintain a good welding arc.
MIG lays down a lot of weld metal, and does it fast - but with some spatter.
TIG is slower, having to feed the filler materiel by hand. But it is much more refined and controllable, and capable of maintaining a very low amperage arc. That allows you to pinpoint the arc, and reduce the HAZ (heat affected zone) of your weld bead. If you get showered with ANY sparks from TIG, you are doing it wrong...
TIG is also more expensive over all, considering the equipment and consumables costs. If you are building a structure go MIG. If you want to attach two sheets of aluminum foil together for the space shuttle go TIG.
Willie