View Full Version : Aluminum parts

05-04-2006, 09:30 PM
Has any one figured how to get aluminum parts back to the original, factory fresh bright finish. I am not talking about polished parts but factory fresh bright cast finish.
Thanks, Tinkerman

05-04-2006, 10:06 PM
Soda or glass bead blasting is about the best way to do it, that I know of. After that, I recommend a clear coat (now available in "engine paint") to help keep the alu looking nice.


05-04-2006, 10:19 PM
I'm afraid the answer here is no. A new casting is the only way to get that appearance. The problem being that aluminum is a very chemically reactive metal. As soon as it is exposed to air it oxidizes and only the fact that the aluminum oxide adheres so well to the metal below is why wheels stay bright at all after polishing. But eventually the oxidation works its way down and causes the metal to look greyer. A fresh casting whether from a solid or sand mold has relatively smooth finish and is reflecting all the light back (under a microscope it will actually look smooth between the pores) but once it starts to oxidize thats it. Your choice then is to chemically clean, which always makes things worse eventually, because while it cleans off the oxidation it makes the surface even rougher so the next round of oxide will look even greyer. The only alternative to slow the process is to put a smooth polished surface on it. Of course you can also bead or soda blast etc. but none of those surfaces look original either.
Tom Lains

05-04-2006, 10:29 PM
To Alan, Wasn't trying to refute you answer. Am just too slow of a typist. By the time I finished you had respnded already. But was assuming he was trying to get the part to look factory new, which I've not seen a successful attempt yet.

05-05-2006, 05:30 AM
So what's the best way to treat aluminum parts? I'm redoing my engine and planned to get the various alumunim pieces polished. Should I get them clear coated, too?

05-05-2006, 06:46 AM
COFFEE POT CLEANER! (the kind for aluminum pots)works pretty good.
Only used on non-polished cast "raw aluminum" like intake manifolds. Try one of the COFFEE POT cleaners. I applied the cleaner as a wet paste and used a non-metallic brush to scrub. I had pretty good results.

05-05-2006, 07:55 AM
also regular liquid dishwasher detergent works well; rinse well.

05-05-2006, 08:41 AM
On bike cases and carbs I scrub with baking soda (toothbrush) then buff on a cloth wheel with the proper compound. Looks better than new to me.

05-05-2006, 02:08 PM
Anyone tried this stuff?


I've wondered about it, but haven't tried it yet...

For a cast alumiunum finish - where polishing isn't wanted - maybe just the Aluminum/Metal Brightener would do the job, i.e. not followed up with one of the polishes.

Whatever is used, sealing with a nice semi-gloss clear coat engine paint can help protect the alumiunum afterward. I've done this on old motorcycle parts (but they tend to be highly polished, machined or brushed alu, not "as cast").

An alternative, there are some engine paints that pretty closely approximate a cast aluminum finish, particularly if top-coated with semi-gloss clear.

First, a really good degreasing is particularly important. I find disk brake cleaner in spray cans to be handy cleaning/degreasing small parts and occasional jobs. It's cheap, evaporates very quickly and completely, leaves no residue. (It also "removes" many types of engine paints.) Just be careful to use it outdoors with plenty of ventilation and to protect your skin and eyes.


05-05-2006, 03:31 PM
Quick and cheap, oven cleaner.I just did the top end of my Fiat 128. The head and intake looked like new when I was done. The bad thing is the stuff will eat your skin and will either discolor or remove paint. I like to go up to a car wash near me on a warm day. Coat the parts with the cleaner and let them sit for 5-10 minutes. Spray away! Be sure to rinse the parts completely when done. /ubbthreads/images/graemlins/grin.gif

05-05-2006, 11:42 PM
As a degreaser and cleaner acetone works pretty good but it is highly flamable and in an unventilated area can make you feel a little too good....maybe that's why I like my work on industrial machinery!

05-06-2006, 09:38 AM
The most effective solvent for petroleum based products I've ever seen is freon. I used to run total petroleum hyrocarbons analysis via infrared spectroscopy and we extracted our water and soil samples using freon. I used to bring parts into the lab on weekends and degrease them in the fume hoods. Unfortunately it's bad for the ozone. A close second was dichloromethane, also an excellent degreaser and solvent for grease and oils. I used that for other analysis and would also use it to clean parts. Unfortunately dichloromethane is a powerful carcinogen. Incidentally, alot of those fast evaporating brake cleaners contain dichloromethane as the active ingredient, so be careful with them. They are phasing them them out though, the non-chlorinated formulations are becoming more widespread. Acetone isn't quite as effective as MeCl2 or freon but has the advantage of being readily available (nail polish remover)and it's water soluble and not nearly as toxic.

05-06-2006, 11:53 AM
I might as well re-enter the fray here so to speak. Virtually all the previously mentioned cleaners all work well to different degrees. But first, please buy yourselves a good pair of chemical resistant gloves (not latex rubber) for this work. After years of stupidity I cannot get a drop of the current brake cleaners or like solvents on my hands without a bad allergic reaction. As mentioned earlier by Allen and others coat all chemically cleaned surfaces with some type of clearcoat if you don't want to have to repeat in a short while. As these will oxidize the quickest of all especially if they should get wet. Another alternative I would recommend for polishing is combining paint polishes like clearcoat finisher with household ammonia cleaner (the non-detergent variety preferably) in about a 4 to 1 ratio and apply it with #0000 steel wool. This does a terrific job on aluminum and magnesium wheel rims without worrying about ruining the surface. On a heavily oxidized rough casting like a manifold you might try coarser grits like a rubbing compound and a toothbrush for application. The ammonia is an caustic alkalai just like the lye (sodium hydroxide) found in oven cleaner, but not so strong and will not dissolve the coating and aluminum metal as fast.
Tom Lains

Andy Blackley
05-06-2006, 12:15 PM
I have used several "Purple Power" type degreasers, diluted, with very good success as general cleaners/degreasers on just about every thing under the hood, not to mention cleaning cosmoline from old surplus firearms.
Recently I cleaned my intake manifold, in situ, using a stiff nylon brush. Not "as new" results, but pretty good for the limited effort expended.

05-06-2006, 06:46 PM
Another cleaner specific for aluminum is a product called Alumabrite. This is a hydrofluoric acid solution that will etch the aluminum and leave a dull patina on the surface. Good if you want to paint the aluminum. Usually find it at an air conditioning repair shop.


05-07-2006, 05:51 PM
Afternoon all:
Wow what a great deal of info from all of you. I really appreciate it. It is going to take awhile to sift through it. But I certainly appreciate all of the info.
All of the information that you have given me is what this forum is all about. Doing a frame off restoration on any old car is a daunting task. Doing it without this type of support, nearly impossible.
Thank all of you very much.

05-08-2006, 11:45 AM
i have seen the results of ultrasonics with a degreaser bath and this will retain the original surface and clean better than anything else at a microscopic level. i think this is what most carburator rebuild professionals use now because the old carb cleaner is too environmentally nasty.