I am using a thin hard white wheel and white compound on oxidized aluminum but i am getting black blobs on the surface. What am i doing wrong.
I start by wet sanding. Depending on how bad the surface is, I sometimes start as low as 320. From there I work up to 2500, then polish.
White compounds are finishing compound, what’s happening is the compound is balling up on the surface. Use a yellow wheel with brown compound, Tripoli it’s called, then move on tho the white once it’s shiny. Spritz the aluminum with varsol in a spray bottle, it’ll help keep the compound from building up on the surface as well. Once shiny while with a soft rag and varsol to clean the compound off then a different soft rag and plain white flour to take the varsol haze off.
As stated sand first then brown compound.. White is for finish polish. And aluminum will turn you black nature of the beast.
I tried most everything.... Then I found this Bright Works, Inc. Metal Polishing & Buffing Supplies, Technical How to Book and DVD on custom metal polishing, USA (bright-works.com)
Agree with all above. I try different compounds and wheels to see what gives a clean first cut. I've even used dupont 7 and toothpaste (non gel) All kinds of aluminum alloys, then: cast, billet etc. What works on one piece doesn't always work on the next.
Orange wheel/green rouge. PIX if your metal, otherwise its just guesstimates on what steps are needed.
yep wet sand...I start at 600 then go 800, 1000, 1500, 2000, 3000, 4000 and 5000 then polish and usually polish twice. I just did an interior facia on my Buick this way. First time I have sanded over 3000 grit. I then clear coated it. Literally mirror finish. But a hell of a lot of work. That was one piece and it took me most of one day to do, but seriously worth it
Might just be me, but I seem to get the best results with a loose, floppy flannel wheel for final polish.
If it is badly oxidized start with Orange wheel and Brown Tripoli for cut and follow up with Yellow wheel and green rouge. This will bring it back to life. If you want to go further you would use a white flannel buff and a blue rouge for ultra shine polishing. Here is a few parts on my trailer I recently did with 2 part cut and buff orange and yellow only. You can see in first photo the shape the aluminum was in when I started. The second photo is after a first cut with orange wheel and brown tripoli in small sample section. Third picture is still in first cut phase with orange wheel and brown tripoli. Last photo is after yellow buff and green rouge. No flannel or blue used on this. tripoliotafter fi
If the item has been neglected with scratches and light pitting, I use scotchbrite (AKA surface conditioning discs) discs to remove any surface oxidation prior to polishing if the surface has been polished before. My choice is 2" discs on a small angle-head die grinder as these will be best for getting into tight places. Start with 'blue' discs for initial cleaning and removal of small scratches/nicks/pitting, then switch to 'gray' discs to remove all scratches from the blue discs. Then polish using a sewn cotton buff with tripoli compound, once you've got all the scratches gone move up to a loose cotton buff with white compound for a mirror finish. My buffer is a 1 1/2 HP @ 3600 RPM spinning 10" buffs, a smaller one will just add time. If you have a real narrow buff I'd suggest doubling or tripling them as a wider buff works better in most cases. As mentioned, 'raking' your buffs when you start getting black build-up while buffing will help by getting the buffing residue off the buff. I can't stress enough how much time the scotchbrite discs save over sanding. I can take a pretty nasty valve cover and have a fully finished part including polish in under 2 hours if not less. The only time I use sandpaper is to blend out deep scratches/nicks or heavy pitting, then I use 600 grit 6" discs on a foam-backed pad, then follow up with the discs. If you're doing a large flat surface with texture like diamond plate, use a larger scotchbrite for initial cleaning to get the oxidation (blue if it's heavy, gray if not) then buff. Here's a motorcycle ignition cover. Heavy scratches/gouging, oxidized in places and with what's left of the factory clear coat. Prepped for polishing. Couldn't restore all of the damage, but got most of it. All of the clear coat is gone. About 15 minutes work. Finished part, about 1/2 hour total time. Except for the engine covers, there's two of everything so not all parts are shown. This was about a day-and-a-half's worth of work start to finish. And yes, you're going to get filthy dirty... It's critical to get as much oxidation off as possible as buffing does a poor job with removing anything more that light amounts. It contaminates the buffs and reduces their effectiveness which is another reason to clean the buffs.
As the final step, dust a soft cloth with corn starch and rub on the aluminum. This picks up any remaining polishing compound. Blow the corn dust off with compressed air, or wipe with a clean cloth.
Lots of great info & advice on this thread! I have nothing more of importance to add, but a thank you for the corn starch info...I had never heard that before & will definitely try it! I have all different wheels, compounds/rouges...My problem is as always time! God Bless Bill https://www.jalopyjournal.com/forum...ar-transport-hauling-open-or-enclosed.614419/
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