Aluminum corrosion

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This is neither a welding topic nor machine question but since you guy are the first and foremost experts on the metal subject I figured I would get the best advice from here. Sorry for the off topic post.I am rebuilding my old daily driver and wanted to spruce things up a bit. I decided to powder coat the valve covers while I do the engine work. After receiving information from another individual that oven cleaner was the damn near best thing to prep the AL valve cover I went and got a couple cans. The person failed to mention what type or what active chemical I should be looking for. So armed with my “Easy Off” oven cleaner I sprayed it on and let it sit overnight as per the instructions. The next day I started the wash down and to my shock the covers were destroyed! They are a total mess and I feel like an idiot for taking someone’s word so literally. The covers were once clean and smooth. Now they are pitted and severely discolored. I have tried everything from oven cleaner to Home Depot type rust remover specially formulated for AL. I have even tried diluted muriatic acid. The acid works slightly but it is deadly and takes a lot of work. I am also afraid that I will not have any metal left if I go this route. There are these salty grains left on the metal as well (as seen in the second pic). They do not come off very easily without some sanding. I am thinking the only thing left to do is to sandblast them clean. I am not worried about changing the dimensional tolerances since they are only valve covers and are not a mechanical part. Attached are some pics of my horrible mess. Does anyone know what I can use or do in my situation?Tomorrow I am heading down to Harbor Freight to pick up a blast cabinet.Last edited by MicroZone; 05-06-2007 at 09:39 PM.Reason: very large pictures
Reply:Blasting is the only option..You can't make the pics any bigger can you??? ...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:The time and effort it would take to restore those isn't worth it. Go get a new valve cover. Is that a Honda valve cover?John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:x2.  Get a new cover.  Easy Off can be used, but can not be left to sit on aluminum, it must be quickly removed.
Reply:Re-sized the pics...John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Sorry about the size. I was afraid you would not be able to see the grainy spots. The cover is off a V6 Mazda KL engine. If the covers were not $350 and $280 each I would get new ones  . I guess blasting it the only option now.
Reply:Hit the salvage yards or call around to recycle yards, I bet you could find a set for $100. If you can't find a set, let me know and I'll find you a set.John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Wire brush or blasting would take that off.  Can you use epoxy to fill pits before powder coating?  Many coatings designed for aluminum suggest the aluminum be washed in aluma-prep and alodine to remove corrosion and restore the corrosion resistance of the aluminum.Last edited by 76GMC1500; 05-07-2007 at 12:09 AM.
Reply:Find a local anodizer.    As long as the part does not have any grease on it, they can do a heavy etch and follow it up with a clear anodize.   Ask if they can do a 204-R1 process.    The cover will come out of the tank looking like new.    The etching process will take a thousandth or two of material, but it will be more consistant that using a media blaster.There are no small projects
Reply:That sounds like a good option. Isn't that process a little pricey for our teenage friend?John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Originally Posted by MicroZoneThat sounds like a good option. Isn't that process a little pricey for our teenage friend?
Reply:Sorry, just a stupid assumption from all the gathered information.  Have you checked your local salvage yards yet ?John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Where I live (Northern VA, DC area) salvage yards are not what they used to be. They're overpicked and way overpriced. Online is the way to go for cheap parts. Sad isn't it?
Reply:Ya, Easy-Off will clean aluminum.  It (and most any other alkaline substance, like its main ingredient LYE, or SimpleGreen cleaner, or GreasedLightning cleaner, etc) will clean aluminum.  With only a slight bit more time, they will also -EAT- aluminum, like you found out.The time to clean aluminum with those types of chemicals is usually measured in minutes (2, 5, 10, maybe 30 for a weaker solution or hard anodizing, etc) and NOT in ' leave it on overnight' time.To smooth out the pits, you are pretty much going to have to mechanically clean/blast/sand/brush/polish the metal.  The process(es) you use will depend on your time, money, tools, and the desired final finish.Tools to use?  Wire brushes, ScotchBrite pads, etc.  If you go the media-blasting route and are not familiar with blasting, PRACTICE-PRACTICE-PRACTICE on some similar but scrap pieces to get a feel for the tool.Regarding the plating shop, find one and call or talk to them and see if your two little pieces can go in the rack/tank with another job.  Maybe the price won't be that much after all.  It should be less than replacement parts, and way less than a blast cabinet, media, and a big-honking air compressor would cost.BTW, if you are just going to powder coat them, clean them and rinse them and wash them down with some solvent (like acetone, a favorite for cleanig grease and oil off of aluminum), and then just powder coat them.  The powder is going to cover and smooth a lot of the surface anyway.
Reply:Great information Moon, very thorough as always!John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Did a little "blind" searching for you because I'm not sure what year, make or model of your car. Found a set of V-6 valve covers for an '02 Mazda 626 - $50.10 from a recycle yard in Kentucky. Their phone is 1-877-684-2398.John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Man you guys are amazing! How can I even thank you for your inputs? I was ignorant and figured if Easy Off was ok to strip the AL why not leave it on there for some time to etch down to clean bare material. I was even instructed to do so by someone. They showed me before and after picks of a head they recently stripped and I was sold. What was strange through; was that when I applied the Easy Off I got this violet/purple ooze out of the metal. I do not know if it was a reaction between the UV dye I had in my oil or if the AL was excreting some dissolved material. Either way my hands are itching to get hold of a blast cabinet. I'm heading off in a few to go pick one up. Whether I use it or not depends on how well the inside of the valve cover turns out first. I'll post update pics later on tonight.BTW Micro thanks for the search. Its a 95 Mazda Millenia L (non-supercharged)Last edited by yellow; 05-07-2007 at 11:47 AM.
Reply:95 Mazda Millenia L (non-supercharged) >  $20 each and up from a dozen recycle yards all over the east coast - FL, AR, TN, NC, LA. Take your pick. Always a good option if the blasting turns out bad. John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Originally Posted by yellowThe dipping/etching option is a bit out of the way and I could only dream what they would quote me on a job like this; although
Reply:P.S.  Let us know how it comes out, and what you decide.. Ive never attempted what you are doing and am allways curious.Various GrindersVictor Journeyman torch200cf Acet. 250cf oxygenLincoln 175 plus/alpha2 gunLincoln v205t tigLincoln 350mpEsab 650 plasmaWhen you can get up in the morning, Its a good day.Live each day like its your last.
Reply:Thank you for all the above suggestions. I decided to go with the sandblasting method. Just a refresher on what I started out with.
Reply:Did a little cleaning and this is what they turned out to be.
Reply:that looks a lot better63' Lincoln SA200 2008 miller trailblazer 302fibre-metal pipelinermiller camo BWEand all the guns and ammo a growin boy needs
Reply:This is total blasphemy but these were my tools. Blast cabinetYou will not believe it but this is what I used for my air! After years of holding on to this thing I can surely say it’s well worth every penny. Pumped air better than some larger compressors.Tomorrow all I have left to do is some minor cleaning and then powder coat them. If anyone wants pics of those I can post it up as well.
Reply:Looks good, great job!John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.comSweet.  Looks much better.  Plus now you have a blast cab.  Post pics of the powder coat if you get the chance.
Reply:Update:Finally got them powdercoated. I used Mirror Chrome powder.
Reply:Looks good yellow, GREAT job! Did you do the powercoating yourself? What kit?John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Did it all myself from start to finish. I used in my honest opinion the best gun I have ever held... Harbor Freight Powder Coat gun. It sure beats the crappy craftsman one and a few others I have owned in the past. http://www.harborfreight.com/cpi/cta...emnumber=94244I used Mirror Chrome Polyester powder from Pendry Powder.https://www.pendrypowdercoatings.com...efa72f6b05aab5and finally my home oven...
Reply:Great job with the blasting! How big is your compressor? Always thought you need a big honking unit to get enough air. Been holding of on a cabinet because my compressor only looked about your size, hhmm. Gonna have to look at cfms again.Latest Toys Miller 180 Mig and Elite Mask!!Wright Welder 225ACShop OutFitters 20/20 Bending SystemHypertherm 380 Plasma30 Years of Sparking (Electrical & Welding)
Reply:That was always my thought as well. Funny thing is that I just bought a 60 gallon 165psi compressor midway through this project but it was more "convenient" to use the smaller compressor outside. I was really surprised how well it worked. I just kept pumping away. It’s the 8 gallon 120 psi Harbor freight compressor with something like 6 cfms at 90 psi. It has to be a lot higher than that for it to have worked so well. I really didn't ever have to stop for it to catch up or anything. I gave it a break every 20 mins or so just because it was 90+ degrees out and I didn't want to overheat the motor. Worked like a champ and I only paid like $89 for it. Great buy!
Reply:WOW!  Those turned out awesome!   Great job!
Reply:Originally Posted by yellowHaha.... that's a bit funny. I'm actaully 30 this summer; 4 undergradates at Virginia Tech and one Masters.Finance, Mechanical Engineering, Environmental Engineering, and Electrical Engineering. I just completed my Masters in ME last May. Real life Van Wilder!The dipping/etching option is a bit out of the way and I could only dream what they would quote me on a job like this; although I assume it would produce a near beautiful finish. Thanks for all the suggestions. I always wanted a blast cabinet so this is the best excuse for one. I got in contact with some people parting out a few cars to source replacements in the event I totally butcher them.
Reply:nice looks good63' Lincoln SA200 2008 miller trailblazer 302fibre-metal pipelinermiller camo BWEand all the guns and ammo a growin boy needs
Reply:You used your home oven to cure them?  I"d be worried how my next roast might taste.Latest Toys Miller 180 Mig and Elite Mask!!Wright Welder 225ACShop OutFitters 20/20 Bending SystemHypertherm 380 Plasma30 Years of Sparking (Electrical & Welding)