[Opper77]

The above about the stainless brush is a good point. Aluminum has whats called a "refractory" oxide and as stated has a much higher melting point than the base aluminum....this is why when you get aluminum hot enough to melt it appears to have a "skin" over the molten pool.

When you TIG weld alum. you must use AC High Freq. current to break up this oxide and penetrate properly. No amount of cleaning with ANYTHING will get rid of it; as it forms as soon as oxygen touches the material. Any MIG welder capable running alum. will either have an extra external box or internal circuit that is basically just a transformer (regular MIG is AC rectified to DC) that enables breakdown of the oxide layer.

Also, one thing to note is that solid steel wire uses smooth grooved drive rollers while tubular (fluxcore) and aluminum use knurled groove drive rolls and if you're going to run alot of wire, proper alum. setups use a "pull feed" gun in place of the "push feed" to avoid feeding problems.

I have used aluminum stick rods in a pinch, but IMHO they are crap once you're used to making art with a good TIG setup. My grandfather is a big fan of the oxy/acetylene setup on aluminum and has done some decent work with it on light gauge sheeting on his '62 Mac.