Best technique to weld painted .093 AL square tube together minimal paint burn????

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I've got some 4.5x4.5" by .093" wall thick  aluminum square tube being delivered in a couple of weeks. I'll be cutting it down to 4' long sections and then welding on a 3/16 thick 8x8" plate centered on the ends. I've never welded painted aluminum extrusion before. Only extruded aluminum I've welded is mill finish. I do know from trying  to fix a cast aluminum part that the paint will burn and the smoke will screw up the welds. Obviously the paint needs to be removed. Do people typically wrap a wet rag a few inches from the end to prevent the heat from travelling down the tube and burning off the paint finish? Maybe it's not worth the effort? I'm going to have to touch up paint the welds anyway, just dont' want the paint blistering off in a few months because I was too lazy to do preventative measures. This tube is normally used for patios and carports. I'll be using it for something different though. The reason for getting tube that is already got paint on it is because the factory paint job is always better and cheaper what I can do myself. Also I need the lightest thinnest walled tubing I can find that is around 4" wide and this is all I could find. All the other big square tube is at least .125 thick wall.  I've started to build a powercoat oven, but that project is a long ways off from being done.
Reply:Originally Posted by AluminumWelderI've got some 4.5x4.5" by .093" wall thick  aluminum square tube being delivered in a couple of weeks. I'll be cutting it down to 4' long sections and then welding on a 3/16 thick 8x8" plate centered on the ends. I've never welded painted aluminum extrusion before. Only extruded aluminum I've welded is mill finish. I do know from trying  to fix a cast aluminum part that the paint will burn and the smoke will screw up the welds. Obviously the paint needs to be removed. Do people typically wrap a wet rag a few inches from the end to prevent the heat from travelling down the tube and burning off the paint finish? Maybe it's not worth the effort? I'm going to have to touch up paint the welds anyway, just dont' want the paint blistering off in a few months because I was too lazy to do preventative measures. This tube is normally used for patios and carports. I'll be using it for something different though. The reason for getting tube that is already got paint on it is because the factory paint job is always better and cheaper what I can do myself. Also I need the lightest thinnest walled tubing I can find that is around 4" wide and this is all I could find. All the other big square tube is at least .125 thick wall.  I've started to build a powercoat oven, but that project is a long ways off from being done.