by bgsengine » Sat Jun 19, 2021 7:42 am
I'd suggest testing first on a scrap block but most of the discoloration or damage would come from when the moisture oxidizes on the metal. to prevent that oxidation, you got to either prevent moisture, or prevent oxygen - chances are anything you use, you'll never get that shiny new polish of aluminum that is left from a casting mold or press and you may have some color shifts over pattern areas (darker-lighter-darker) but other than that if you can scrub it clean in ultrasonic and immediately remove moisture once done (in other words, minimal acidity of the cleaning solution, and minimal exposure to oxygen after it comes out, immediate drying and then immediate sealing with a coat of something that don't mix with water) chances are you'll be able to do fine.. but any case, simple green and dawn are both just surfactants that break surface tension of water to allow it to penetrate where it otherwise could not, and then the soaps bind with loose dirt and debris to rinse it away (and leave residue on the surface too) So, pretty much it is gonna be all about controlling the acidity (Ph balance) of the solution, and making sure anything that lets aluminum react with oxygen (water, soap, etc) is eliminated from the remaining surface and then coating with a water repellent finish (oil, obviously, but if you plan to paint the outside, may want to use something like mineral spirits and then a light blast of spray-on shellac, which readily dissolves with plain old alcohol)
How poor are they who have not patience. What wound did ever heal, but by degrees? - Iago (Othello Act II, Scene 3)