On 23 July, 09:22, "Fredxx" wrote:

My MIG is wired for gas, and my understanding the ideal polarity is the
reverse for gasless wire, yet I can make satisfactory welds. *

Yes, reversing the polarity is ideal. If you don't do this, you'll
burn the base metal, just as reported here.

Some cheap gas/gasless welders run permanently with gasless polarity
(wire hotter than base), so they would suffer from poor penetration if
used for thick metals, which admittedly they're unlikely to be used
on.