what gas is the most appropriate for spray transfer?

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hi everyonejust started with a mig welderuntil now i just tried CO2 as a shielding gas, but i am obviously appealed to try spray transfer (on mild steel)is it 18%CO2+82%argon appropriate for spray transfer or would it be better to try argon with 2% oxygen?thank you for any advice
Reply:http://files.aws.org/wj/2006/02/wj20...j200602-46.pdf
Reply:i use 95/5 argon /oxygenChuckASME Pressure Vessel welder
Reply:In most cases with MS you need at least 90% argon but not ALL cases because helium can also facilitate spray transfer
Reply:Depends on how much guts your machine has, too.  My PowCon 300SM will spray at one setting only with C-16.  Now, I have better choices available and usually spray mild and stainless steels with C-3.
Reply:Yup, I would say the machine should dictate the gas. A smaller machine with lower voltages would dictate a Ar/Oxy mix or at least a very low Co2 and Ar mix. My MM210 will spray with 92Ar and 8Co2. 98/2 Oxy would be ideal for it...too bad I don't have any.
Reply:I have never done spray, but it intrigues me to death. The reason for the 2%oxygen is?? to run hotter than helium?? I have mig welded aluminum, and used an argon/ helium mix to get more penetration. How much oxygen is too much, causing instant oxidation?? Or, like a test motor we once tried, we holed a piston or 3 using oxygen injection instead of water injection. Who knew the wetness of the hydrogen in H2O would be needed??!!!??
Reply:The addition of O2 reduces the amount of energy required to achieve spray arc in addition to the fact that it increases bead wetting.  It does increase oxidation potential, but not usually to the extent that it exceeds the capability of the deoxidizers in the wire (assuming ER70-S6).-Heath