General Cold Front

Welding thin panels, especially at the edge (window frames come to mind) it's very difficult to prevent buckling

Even with a good MIG on low setting, it's a good idea to stop after each spot weld, using a damp cloth to quickly cool the area before continuing..

You can get a cold putty from Frosts [1] Cold Front] that sucks heat away locally, put it around edge near weld to stop distortion, to some extent can be re-used. Use an 80/20 or 95/5 Argon mix* on low power I'd think and keep stopping, do it in short bursts.

• CO2 seems to need a lot more power!