chosing mig gas

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This may be a dumb thing to ask but here goes. Is there a gas or gas mix for mig welding that is better for not perfect conditions, such as rust or paint that is in a corner or you cant get it all out? I only use good wire to mig with to help the cause.Thanks grinder2
Reply:You can use C/25, pure Co2, or 92 argon /8 Co2.  Pure argon does not work well for me.  As far as rust and paint, CLEAN IT OFF.  David
Reply:I really don't think one gas is going to be much better than another for burning out crap. I use 75/25 for all short circuit steel mig. With limited money and space it's the best for what I do. Mig likes clean metal. Rust will be your worse problem. If you start on clean metal and weld toward and around the corner it will burn off what little paint you can't get off by reasonable efforts. yes you do to do the best you can to get it off with wire brushes, scrapers, ect.Last edited by tresi; 04-13-2008 at 12:10 PM.
Reply:David is right. The mig process does not like dirty metal. The cleaner you get it the better your weld.
Reply:Use the wire with the most combined Deoxidizers, which is ER 70S-2    JohnSMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :
Reply:Fluxcore wire seems to tolerate dirty metal better than solid wire and gas, as does stick welding.  Even so, I still try to clean the metal as good as possible regardless of the welding process used.  You can try a dremel with a carbide burr to get help clean into the corners.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:100% CO2 will do SLIGHTLY better than the argon mix, but if you can't get it clean, you should be switching over to a slag-producing process, like FCAW.