Cleaning aluminium components in situ

[1969Mk3Spitfire]

I’ve always admired restored cars with as-new aluminium components, inlet manifold, gearbox housings etc, all presumably blasted clean as part of the restoration.

How do other members approach this? I like to see a clean engine bay but wouldn’t want to start removing items just for cleaning. I use Screwfix gunk/jiser equivalent and a soft wire brush, if access allows, but I’ve yet to find a way to really enhance the surface finish.

Any magic potions to safely clean aluminium in-situ?

[Chris A]

5 minutes ago, 1969Mk3Spitfire said:

I’ve always admired restored cars with as-new aluminium components, inlet manifold, gearbox housings etc, all presumably blasted clean as part of the restoration.

How do other members approach this?

I just keep the bonnet closed so I don't see inside 😁

I do actually like to keep it clean(ish)

[GrahamB]

I once tried to clean some aluminium trim using a weak solution of caustic soda (and rubber gloves) . It cleaned the aluminium but also proved to be an effective paint stripper!

[Iain T]

33 minutes ago, 1969Mk3Spitfire said:

Any magic potions to safely clean aluminium in-situ?

Most parts are just sand castings so have a rough surface and never made to look decorative. For castings you would really have to remove the part and use a linishing and polishing mop to give a polished surface. However for me that would look odd. I use Autosol to polish aluminium/stainless steel/chrome trim parts. 

Iain 

Edited April 9, 2023 by Iain T

[1969Mk3Spitfire]

Thanks for the comments. I don’t want a polished finish and agree that it would look odd. I’d simply like to restore close to as-cast. Caustic soda sounds interesting, I may try it on something hidden. There’s the added danger of the potential to make it worse.

[Iain T]

Try baking soda solution first? Never tried it but Google has...... At least it's not as harsh. 

[GrahamB]

Yes. Baking soda, sodium bicarbonate, is probably safer as would be washing soda, sodium carbonate.  We used caustic soda as we had some readily to hand. Afterwards we wished we had used something less aggressive.

[mark powell]

I purchased a 5 litre container of heavy duty aluminium cleaner from an Auto chemical supplier. Saw the van when he was delivering to a dealer, stopped and bought one.  Autosmart, I think it was.  Very HD, follow the instructions!

[JohnD]

Caustic soda will DISSOLVE aluminium!  Prob Ok to clean but wash off and don't leave parts in the solution!

[GrahamB]

14 minutes ago, JohnD said:

Caustic soda will DISSOLVE aluminium!

That is why we thought it might work, dissolve the tarnished surface layer  then wash off.  The same idea as cleaning coins by placing them in acid.  It was just too aggressive especially to the surrounding paint.  And you must be used to handling corrosive chemicals to do it safely.

[Wagger]

You need something that will dissolve the oxide and not the base metal. Nitric acid will dissolve copper oxide more than copper. Sulpuric acid dissolves copper and you end up with copper sulphate.

My mother used to boil rhubarb in her aluminium saucepans in order to clean them.

Egg white worked quite well too.

Edited April 9, 2023 by Wagger

[1969Mk3Spitfire]

12 hours ago, Wagger said:

You need something that will dissolve the oxide and not the base metal. Nitric acid will dissolve copper oxide more than copper. Sulpuric acid dissolves copper and you end up with copper sulphate.

My mother used to boil rhubarb in her aluminium saucepans in order to clean them.

Egg white worked quite well too.

Now there’s a thought, oxalic acid. I keep a bag of crystals on my boat as they have many uses. They are generally good at stain removal from around the waterline on GRP and will remove rust/tarnish from rigging fittings.

Another probable example of mother is always right.

Thanks to all.

[PeteH]

Not sure about aluminium, but my go to for copper is White vinegar crystals dilituted, brought my old copper ships brass and lights up a treat. I use it for an annual descale and sanitising of the motorhome water systems too, as it does not affect Stainless steel which the more popular Chlorides can.

Some grades of stainless are not chlorine resistant, as we found out in the aftermath of the 80`s "legionella" outbreak when air con units and cooling systems where being "overdosed" in an effort to kill off the bacterium!. Leading to scrappage of very expensive equipment which was failing pressure testing. On one ocasion it put a Laboratory in Petersfield out of action for several weeks!.

Pete

[Wagger]

Odd is it no,. a Stainless steel sink and surround is more toxic than a wooden chopping board. Friendly bacteria in the wood if you are careful. Copper door finger panels and operating tables kill most bacteria, given time.

Spinach has Oxalic acid too. I wonder what the disolved parts of the pans did to our stomachs? AND all of the worn tines of the old mixing fork which was half as long when I was a boy compared to when my elderbrothers first saw it.

There you go, if you don' like spinach, clean your ally with it. Dunno what Popeye would say.

[Colin Lindsay]

For me, I don't think it's so much the cleaning of alloy parts as keeping them clean. I can get them to a certain level of shininess, but after time it fades very quickly. I have photos somewhere of a GT6 alloy bellhousing polished to almost mirror brightness, but no idea how long it lasted, unless it was lacquered. I'm not intending that myself, but still would like to keep shiny bits shinier for longer.

[Unkel Kunkel]

In general, I would be wary of using alkalies on Aluminium alloys as  depending on the type of Al alloy, the results can be disappointing - it can go black.

The Al  oxide removers tend to be acids rather than alkalies  - Phosphoric (a U.S. commercial product is 24% phosphoric)  hydrochloric, oxalic, citric.Some advocate citric or citric and acetic together.A detergent/ degreasing agent seems to be added to the mix.

Oxalic acid is  found  in  rhubarb , spinach etc  etc but the amounts are very tiny.

Even Popeye’s  heroic  spinach intake would be  OK for him, but the amounts used for cleaning purposes  and these  sort of jobs are huge in comparison and are best regarded  as poisonous. 

Once the dull oxide layer is removed, the bright alloy is exposed and the oxidation process resumes.

It is slow though, and it reaches a stage where the oxide layer itself slows  the process.

Keeping that initial brightness will depend on inhibiting that  oxidation  - by keeping the Al away from oxygen - by polish, oil,  paint, lacquer - whatever, and keeping it polished and the protecting layer intact.

 

Edited April 10, 2023 by Unkel Kunkel

[Wagger]

If you can afford it, have it anodised. Like the Vitesse 'Bumpers' it lasts for years and is very hard. Otherwise, find a laquer that will stick, or even paint it!