Chris,
Despite the recommendations listed, blasting of aluminum in any way--glass bead, walnut shells, etc. is generally discouraged by those who wish to maintain the original finish. Any kind of blasting strong enough to dislodge crud will affect the surface finish since aluminum is so soft.
When my engine was rebuilt by Metric Motors, the valve cover came back looking like it had just been ejected from the mold in the casting plant! When I queried Metric on it, I asked how they achieved the look, and they said bead blasting! I said impossible, and showed them the photo I had taken. He then emailed me back and said, yes I was right, and he was wrong--the surface was clearly not bead blasted.
So, how to achieve that freshly cast look? They used a commercial solvent from Safety-Kleen which is a "carb cleaner" and let the thing soak in that for a while. You might try over the counter carb cleaners, and a nylon brush. Brake cleaner is a strong solvent as well.
In the car wash industry we use a very very nasty chemical to clean the walls of crud and sludge that builds up. Interestingly, it is sold as an "aluminum brightener". I have not tried it in that application. It is nasty because it contains either ammonium biflouride or hydroflouric acid, a nasty acid that will pass through your skin and attack your bones without you knowing it because you can't feel it. In order to allow you to know that the stuff may have hit your skin, and to boost its effectiveness in cleaning applications, they mix it with hydrochloric and sulfuric acids! Egad, what a toxic brew. But, hot damn! The stuff literally melts EVERYTHING that is on the wall away, except the wall!
If you have the wherewithall to try this stuff, you can go to any car wash and ask the owner or manager if they have a small quantity of wall cleaner you can try. A weaker brew of the stuff is sold as a wheel cleaner under the Eagle One name in auto parts stores. There's another one called Hot Rims, and probably other brands of Chrome and Wheel cleaners I don't know about. Look for the ingredient Hydroflouric Acid.
As usual, test on a small area first. Oh, it should be stated that this stuff should not be used "in situ" but only on parts removed from your engine bay. Spraying aluminum brightener inside your engine bay could cause problems.
Now for the inevitable off line questions: can I supply some? No, I'm afraid. I buy the stuff in 5 gallon pails that I either pick up or have delivered by a local supplier. Handling the stuff is a harder challenge than using it. I can't get small quantities into small containers with the tools I have. Shipping it, as you would imagine, is almost impossible as well. BUT anyone wanting to try it out is welcome to come to Michigan. I'll give you some lessons ("Wax on, Wax off") on my walls
and then help you on your aluminum parts!
Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored
