Bumper build questions

[TheGary]

Buying shielding gas in small tanks becomes very expensive. If you go with flux core be aware that humidity will rune the wire within 3-4 months if you leave it in the machine. If you do use flux core I would buy it in 10lb coil and if it is going to be a while between uses, remove it from the machine and seal it in a plastic bag with some desiccant to remove humidity or better yet vacuum seal the bag. A nice way to store it is in a 5 gal. pail with a rubber sealed lid and an oxygen absorber pack in the bucket. Flux core wire does not like paint or heavy rust so prep will be important. Co2 will be the cheapest shielding gas to use but it will leave a lot of spatter. Probably the most widely used gas is 75/25 argon, co2 but a small bottle will not last very long. About the smallest I would use is 125 cu.ft. size . That size tank will probably last about as long as a 10 lb spool of hard wire. They do make dual shield wire but just suffice to say it is not what you want to use .
For outside use , probably flux core like Lincoln NR211 mp. It is very much like stick welding but you have more control over the weld puddle and gaps are much easier to fill than it would be with stick welding. If you have a way to block the wind you could use hard wire and gas but you will need to always block the wind , even a mild breeze will blow the shielding gas away.