cleaning aluminium for welding....??

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Hi,I started to do some more al. work I was wondering what the experts out there do for pre weld cleaning.I usually go use my SS brush a bit then wipe the area with acetone.what do you do?is just acetone enough? because the brush scratches and messes up the finish....
Reply:if its new billet aluminum just a acetone wipe with a clean rag suffices for me..dirty stuff gets the brush treatment too..other than that......zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:If there is an oxide present on aluminium it takes approx double the heat that it takes to melt underlying aluminium.An example of this oxide  is  that when you polish a piece of aluminium ,you are polishing away the oxide layer.The welding process mostly does benefit from  a mechanical or chemical removal of the oxide.If badly oxided acetatone will have little effect other than to remove any oily surface deposits. To remove deeply ingrained contaminants often takes soaking in the stuff. Mind you acetone evaporates fairly quickly.From my shaky memory it takes approx 600 degrees Celsius to melt aluminium and 1200 degrees to melt the oxide.Thats about 1100 F and 2200 degrees F.  It is really easy therefore to inadvertently melt through a thin plate like an alumninium dingy for instance.( More on that later and the famous "this will only take you 5 mins repair ")If you are using TIG it makes sense to remove the oxide especially if your machine does not have an AC balance control.Grahame