Hello all. I first learnt about Citric acid for rust removal from the very knowledgeable people that frequent this site. I am now officially a member of the fan club. I was telling a mate about it today and he asked if there was something similar for aluminum. I thought to myself great question, but I don't know the answer. So if any HAMBers would like to share their secret brew for cleaning up aluminum castings I would be very grateful. Thanks Steve from down under
I never measure the amount of citric I just pour it in give it a mix and soak the parts. I don’t think it matters what metal you use it on. it’s very mild
I have an old bottle of "Aluminum Jelly" around here someplace. It is Phosphoric just like for steel.
Depending on what aluminum parts you're wanting to clean I've used Aluminum Brightener, I purchased it from an industrial cleaning supply. It can be mixed with water to the concentration you desire. Like citric acid, it won't cut grease or oil. I've used it on the truck and trailer in my avatar many times. A quick search shows ZEP products are available in Australia, their stuff is pretty good. Note: if it's a dimension sensitive part I'd be very careful.
Best thing out there for Al is good old Easy Off oven cleaner, not the fancy new safe stuff. The issue is it can work way faster than you can pay attention and etch the aluminum beyond repair. On our Bulk Tankers there is a citric acid etch that can clean them after lime and cement dust makes them look old, the problem is, once you use the process you can never go back. It looks like clean aluminum but the pores are now open and it will always get stained and soiled and need the same wash from there on out.
Easy Off? Aluminum?... Bad Juju there!! AA lost a multi-million buck 767 Pylon due to someone using it to clean up some hydraulic fluid coking.
As I said, Easy off works but can goo off too quick. We have been using it to remove anodization since the 70s on BMX components. Best to spray some on and do some quick tests instead of letting it go to long and wrecking the part. Don't doubt 40 to 50 years of real world experience
BMX !! My boys did that back in the 90's. Still have a Titanium Black Lite and a GHP hanging in the garage!
Mag wheel cleaner with Phosphoric acid in it , brush it on, it’ll foam up abit the using when scrubbed with a soft brush and hose it off. Good for raw unpolished Ali.
Had some stuff I got from the weld shop when I worked for AMF called Alumiprep, it was used to clean aluminum before welding, stuff worked great cleaning my old Harley cast aluminum engine cases.
Many many years ago , I kept a few cans of a product called “ Mr. Muscle “ . I would soak a carbon covered , piston in a can of it for an hour or so , and God could not determine it from a new piston . This stuff left the shelves many years ago . I have no idea what it was , but it was the best I ever used .
Not quite the same, but sodium hydroxide will etch aluminum. Sodium hydroxide is the active ingredient in oven cleaner. Sodium hydroxide is also known as lye or caustic soda. Sodium hydroxide can clean the aluminum, but the aluminum will be dull. It will ruin a polished finish.
Aircraft Spruce has it, but they don’t recommend its use on cast aluminum. Not sure why, perhaps porosity?
I wonder whether you could let them soak a little in Gibbsbrand lubricant, might help. - I’ve had success with steel bolts in aluminium housing on motor bike parts, but may not be as tough as pistons. Perhaps others will comment.
Most aluminum cleaners/brighteners contain hydrofluoric or phosphoric acid. Sometimes both. These cleaners brighteners are not all created equal depending on the concentration of the acids. I recently bought some Aluminum Brightener by Quality Chemicals from Amazon. I put some in a pump spray bottle and sprayed it on a bell housing and it immediately started to foam and etched the aluminum to a gray color. That was OK because the etched surface provided a good surface for paint which I intended to do. I bought aluminum cleaner/brightener from one of auto chain stores (O’Reilly’s) and it did very little to the bell housing surface. Most say to dilute with water. The big truck companies use brightner/cleaner to clean/wash bare aluminum semi trailers, fuel tanks, etc but I don’t know the concentration. Be aware once aluminum is etched it’s a long path getting it back to a polished surface. A safe aluminum cleaner/brightener can be made by mixing equal parts of vinegar and water then adjusting the ratio as needed. Citric acid would probably work well also but I have never tried it. Aluminum corrodes very easily and the corrosion actually protects the surface when it starts to form. If a polished surface is desired it must be protected by wax, clear coat, etc.
Here’s what we used on my dads Truck after washing it, steps, wheels, fuel tank etc. didn’t harm the paint. We’d use a weed sprayer with water and pour a “gulp” in, shake it up and fine spray it on. It would lightly start to foam white a bit, then we’d rinse it off. If we mixed it to strong it would streak a bit, so we’d go over it again and streaks be gone. Sorry for the angle of the pic, the jug is kinda buried
I worked in a few of different manufacturing plants in the past, which did powder coating. I want to say we used the same phosphoric acid was for both steel and Aluminum. I could be wrong, lots of water under the bridge since then.
Phosphoric Acid when applied to steel/iron forms iron phosphate which is a gray/black coating. It’s an excellent base for adhesion when painting. When zinc and or magnesium salts are added to he phosphoric acid the process is called Parkerizing that is sealed with oil or wax for corrosion prevention. This is the same coating you find on hardware such as socket head screws/bolts.
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