A few ridiculously stupid questions..

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I have the little Lincoln Weld-Pak 100 from Home Depot, and have been using flux core wire w/o gas.  I just ordered the mig conversion kit and have a few questions... What kind of gas should I use for soft metal up to about 3/16" thick? Also, do I need to run the gas a few seconds before starting my weld, or can I just weld as usual? Can I use flux core wire with gas? I'm just a weekend welder who enjoys building small projects out of my garage. Thanks in advance, and again I apologize for the dumb questions.
Reply:For mild steel and similar, the 75/25 gas is your best bet. Go into any welding supply and say "75/25" and you'll get the right gas for MIG (GMAW) welding. No, just hit your trigger and weld away. You can but it's not necessary. Welcome to Weldingweb!John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Thank-you!
Reply:I agree with all that MicroZone said but you might check on using 100% co2. It works good, your welds will burn hotter which equates into better pen. and I think its cheaper.Might spatter a bit more too,but its not bad.
Reply:And stick to 1/8" with the GMAW process on that little machine, please.If you need to do 3/16" for anything other than making it stick together, use the flux-cored wire.Ditto on the CO2: cheaper and lasts longer, but make sure your regulator is designed for it as it is much colder when coming out of the liquid state.For your machine, and the flux-cored wires you'll use, it would be a waste of gas to use it along with the more expensive flux-cored wires.  You'll stil have the slag.Don't forget to swap the polarity between the two processes.
Reply:Originally Posted by TEKI agree with all that MicroZone said but you might check on using 100% co2. It works good, your welds will burn hotter which equates into better pen. and I think its cheaper.Might spatter a bit more too,but its not bad.
Reply:Originally Posted by gnm109I like C02 also. As you say, C02 is relatively inexpensive and would assist a small 100 amp welder in getting better penetration. I've found that if I keep a jar of welding jelly handy and stick the tip in it now and then, I get almost no splatter.