Aluminum Problems!!!

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Had an old pot (livestock trailer) that needed holes in the floor patched. Never had problems before with this type of repair just clean up with stainless wire wheel lay new tread plate over the thin spot and weld. This trailer hadn't been cleaned properly in a long time and even after the wire wheel and acetone welds were contaminated and you smell the urine being cooked out of the al. First question would it have been better to acid the area first then rinse and acetone? Not sure when the last time this one had been acid washed. Solved some of the problem when I changed spools, was out of wire when this came in and regular supplier was too so went to another and bought two rolls (1 lb.) of weldcote 4043 .035. I had never used this brand before. Couldn't get a weld that wasn't heavily contaminated. Checked all the usual's. The ground was clean and close, even bought new stainless wire brush, checked for gas leaks, made sure no breeze was getting in, etc.. Finally burnt through first roll the second one was not as bad but not good. Thought 2 rolls would get it but these were so bad I ground out the welds with al. grinding wheel so as not to contaminate any worse and rewelded so I went through more than I planned on. After I burnt through the second finally got my usual and most problems went away. Still need to know if the acid should have been used and or what else I could have done to help clean this mess up. Turned a 4 hour job into a 10+. Sorry so long partly needed to vent on that crap weldcote wire.
Reply:Could you see where the contamination was coming from?  Getting pulled in from the sides of the joint, down in the joint, in front of the puddle, from the wire, ect?  I doubt that you needed to clean the metal anymore than you already did, only thing I can think of is that you were too aggressive with the SS wire wheel to get the alu hot enough to smear.  When it smeared it trapped some contaminants under the surface where the acetone couldn't get to it.Did you ever check your rollers to see if some grease or something got onto them?  That would make a lot of sense if the problem got worse the more you welded.Have we all gone mad?
Reply:Most of the problem cleared up when I changed wire from one manufacturer to another but I could still smell the urine cooking out of the al. Still had some even after changing to just a brush not the wheel but I will watch next time how hard I go with the wheel. The problems even showed up on new al. until I changed to the old stand by wire. Just not as bad as on the floor. Could it have been a  bad batch of wire or is this just that bad of wire? Totally went away on new Al. with the regular brand I always use.  I figure this trailer will be back for more work shortly and I want to be able to get in and get out next time.
Reply:Sounds like contaminated wire, I doubt it was bad for the MFG more likley it got some oil in it,Have we all gone mad?
Reply:Personally I wouldn't use a wire wheel to clean the metal, wire wheel will basically just polish trash into the metal and doesn't get it clean or to fresh metal like a sanding disk or grinding rock.  But, yeah it sounds like you got some junk wire...
Reply:Is using a flap wheel and then acetone a good way to clean the aluminum or will the flap wheel grind in the contamination. I want to know the absolute best way to clean it because I need all the help I can get.Also, what are the signs you have contamination ?? I don't do much aluminum but have a rig that can do it.
Reply:Flap wheels really are not the best idea for aluminum for a few reasons.  The grit will come off the pad and embed in the material.  Flap wheels will also get loaded with aluminum and quit working as well.  Then once your wheel gets loaded up it starts to smear the material and can trap more dirt and grit underneath.Aluminum specific grinding wheels are a good choice because they wont load up and smear like ones ment for ferrous material.  Also ive found that carbide burrs meant for non-ferrous metals do an amazing job and require no further cleaning after grinding.As for the best way to clean it, usually a through SS wirebrushing and maybe solvent wash is all you should need.  However aluminum can never be to clean, so keep that in mind.As for signs of contamination, it will look like black spots in the weld bead.  As your welding you can see when pieces come up to the surface and float around in the pool.Have we all gone mad?
Reply:Its a horse trailer.  It will never be clean,. The contamination goes way deep.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:David would using acid help any or is it just gonna be that way
Reply:When i need to weld on these trailers, i take a little sandblaster with me. That works wonders. Try it, you will never go weld alum again with out it. Also, try some 5356 wire.Aaron
Reply:I like to simple green, then acid wash using a light acid solution with a 3000+PSI rinse then low pressure water douching of the entire trailer floor.  This is just maintenance on my own horse trailer.Vantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.
Reply:Using an acid wash just adds to the acidic base (urine) that has already contaminated the area.  Seems to me an alkaline solution would have been better to negate the urine contamination.Sandblasting, if not using the proper medium, can present it's own set of problems when trying to weld aluminum.A little aluminum flux, applied to the weld area, may help the appearance/quality of the weld.The non-ferrous burr is good for cleaning the edge of aluminum, but not very practical in this application.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.