Removing aluminium oxide

Soda blasting would be better, trouble with any blasting though is it does drive some corrosion deeper and does not get all of it out, and if the corrossion is bad you may end up with a pile of dust and nowt more.

Try soaking that in deox-c. Any paint will be preserved and it will soften your concretions. Works very well for me.

A typical example of what I’m trying to remove…

Yep, glass-bead-blasting will certainly shift all that from every crevice…

…but it will also alter the appearance of the whole artefact…..giving it a ‘frosted glass’ effect.

I’ve found that after bead-blasting a reasonable finish can be achieved by polishing with a fine steel wire-brush; I’ve never experienced any problems with corrosion following this (so long as the artefact is kept bone dry). Bearing in mind that I’ve only ever applied this to relics and (earthbound) ‘mechanical’ parts that need to be functional (and not to anything that needs to be airworthy)!

If you’ve got a small sample I’d be happy to bead-blast it for you.

A typical example of what i’m trying to remove. Yes i can pick and scrape but not completely remove this substance. It’s very hard, almost like a calcium build up.

Bead blasting it will save a bunch of frustrating faffing about. (Faffery?)

A typical example of what i’m trying to remove. Yes i can pick and scrape but not completely remove this substance. It’s very hard, almost like a calcium build up.

I know, I’m a LAE as well.

He isn’t talking about an airworthy part but a relic that is severely corroded.

Regardless of airworthy or not, you are introducing materials that promote corrosion.
Yes, it will be slower, but will not stop it.

Even Stainless Steel is not completely corrosion resistant and can promote corrosion, just to lesser extant than typical steel.

One should not shortcut preservation just as one should not correct aircraft maintenance.

There are times when accepted methods of work can be ignore to deal with an issue that cannot be fixed normally, however that usually has a follow up to insure there is no side effect.

OP said pitted, hard to say how bad the pitting is, what factors.
Maybe a dental pick is needed?
Chemical treatments would be a no go because the chemicals may not be cleaned out properly and promote more corrosion.

Scott, can you post some images, please?

I know, I’m a LAE as well.

He isn’t talking about an airworthy part but a relic that is severely corroded.

Was taught same thing at QANTAS many years ago,even my scraper collection is Perspex or hardwood…

+1

you can use stainless steel brushes on aluminium. and as for acids, what do you think Aluprep is.

Instructions:

Wash throughly after use before applying alodine

Bottomline, Aluprep DISSOLVES a layer of Alu, it us used to remove oxidization and other contamination by stripping a layer off. The danger is Aluprep can go where you do not want it go, especially into fine cracks and scratches.
I do use Aluprep, but not every time.

Cleaning with ScotchBrite is just as good, and you control the process better.

The blue /green stuff won’t be Aluminium Oxide as that is colourless. It will either be copper acetate/carbonate (verdigris) or possibly organic (moss/lichen,/etc.). I saw a Land Rover yesterday with a fine growth of Lichens around all the window frames. Something like Domestos might remove that; it will certainly kill it.

2024 aluminium alloy’s composition roughly includes 4.3-4.5% copper, plenty enough to give a green/blue color (or colour as you say 🙂 )

You can use brass or aluminum brushes, but no steel brushes as they will embed steel into the aluminum and cause more corrosion later, same with steel wool. You can try glass,baking soda or dry ice blasting as well.

you can use stainless steel brushes on aluminium. and as for acids, what do you think Aluprep is.

When I was working at McDonnell Douglas, no metal brush of any kind was allowed on the aircraft.

Was taught same thing at QANTAS many years ago,even my scraper collection is Perspex or hardwood…

The blue /green stuff won’t be Aluminium Oxide as that is colourless. It will either be copper acetate/carbonate (verdigris) or possibly organic (moss/lichen,/etc.). I saw a Land Rover yesterday with a fine growth of Lichens around all the window frames. Something like Domestos might remove that; it will certainly kill it.

You can use brass or aluminum brushes, but no steel brushes as they will embed steel into the aluminum and cause more corrosion later, same with steel wool. You can try glass,baking soda or dry ice blasting as well.

With the new abrasives like Scotch Brite I avoid any metal brush. Even Al brushes may have other metals to increase strength, and thus corrosion potential.

When I was working at McDonnell Douglas, no metal brush of any kind was allowed on the aircraft.

You can use brass or aluminum brushes, but no steel brushes as they will embed steel into the aluminum and cause more corrosion later, same with steel wool. You can try glass,baking soda or dry ice blasting as well.

Hello all,

as and licensed aircraft mechanic, some advice:

NO METAL BRUSHES on aluminum, it simply causes more corrosion.
NO ACIDS, that too causes more corrosion (the Cosford Do-17z is a special case to remove the marine growth.)

There are special chemicals that can arrest the corrosion, but by far the best way is:
ELBOW GREASE (tm)

Scotch-Brite (fine) and light oil or solvent and scour the corrosion away until its bright. Bathroom will work, but you can find finer pads.
You could use toothpaste too, but that is a bit too fine.

After either Alodine it (nasty chemical) or use ACF-50 or Corrosion-X as chemical preservatives.

Try this stuff.

I have been using it for years on aircraft and it is excellent at killing corrosion, driving out water, preventing existing or futur corrosion and is a very good penetration fluid. Its saved many an aircraft part and kept many others in a great condition .

I have also used it on my old 1984 Vauxhall Chevette. It killed the little existing corrosion it had when I bought it 10 years ago. With regular treatment it looking as good as when I collected it.

http://www.acf-50.co.uk/

If you are wanting to purchase soem in a lrge quantity or a smaller quantity then I may be able to get you a discount on retail price.

Regards
Mark Jones

We use Phosphoric acid (The bad stuff in Coca Cola) which works quite well..
http://www.ebay.com.au/itm/like/261582731279?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=107&chn=ps

I have used white vinegar to some success. I just empty a few bottles into a plastic container and place parts in there. Cillit Bang grime and lime (orange top one) works wonders on some parts but stinks and you must wear gloves or your hands will go red and sore and the skin dries and falls off! If parts are too big to soak, try wrapping the affected area with srpips of old towel and soak them in vinegar or Cillit Bang. This will prevent it from drying out too fast. Keep giving it the odd go with the soft wire brush as the process goes along, getting the worst off when it softens makes things quicker.

I have also used watered down brick cleaning acid but it needs mixing right and being hydrochloric, works better on iron oxide. Small soft Brass wire brush puts the shine back afterwards.

…the blue/ green stuff in the pitted areas is very stubborn and will not budge.

My preferred method is sand-blasting, or rather, glass-bead-blasting but it is not suitable for all situations, depending what you want to use the part for, or how big it is. In fact, one of the best things to ‘sand’-blast other things with is…

…aluminium oxide!

http://www.stain-removal-101.com/homemade-aluminum-cleaner.html

🙂

http://www.ehow.co.uk/how_4546208_aluminum-cleaner-recipe.html

Thanks for the information guys. Is there anything a bit less industrial that can be found in the Missus’s cleaning cupboard for example?:rolleyes: