Cleaning alloy castings

[Kenneth DeightonParticipant @kennethdeighton43272]

[Kenneth DeightonParticipant @kennethdeighton43272]

I need to clean some old aluminium cast stepping plates that sit on the running boards of a vintage car that I am restoring, what is the best cleansing liquid that I can use,?. sorry no sand blasting available.

[RJWParticipant @rjw]

I've used this stuff recently to good effect on well corroded camshaft covers and intake manifolding!

(No connection other than a happy customer)!

You could also google 'alloy cleaning with phosphoric acid' or 'Caustic Soda + Nitric acid' which brings up results of more agressive mixtures and alternatives to the stuff sold via Raceglaze, but I decided against it, pretty nasy stuff if you get it wrong!

Beware if you go the caustic soda route, the alloy goes as black as night before the nitric strips it off and takes some shifting!

John.

**LINK**

[Bill PudneyParticipant @billpudney37759]

Caustic soda and al.alloy are generally a no-no. A friend once tried to clean his Ariel Arrow barrels (cast iron) and cylinder heads in a caustic soda solution and found that his cylinder heads had disappeared! The barrels were nice and clean though.

best of luck

cheers

Bill

[Involute CurveParticipant @involutecurve]

Soda blasting makes old bike engine casings look better than new, and is quite common in the restoration market.

[RJWParticipant @rjw]

Caustic soda is perfectly ok to clean alloy as long as you don’t leave objects stewing in the brew, the hard graft is getting rid of the blackened residue!
Blasting is certainly my preferred method, but you need a suitable cabinet with lighting and dust extraction, plus a decent compressor – either deaf or very understanding neighbours are a major plus if doing this at home, it’s not a quick job!

John.

Edited By RJW on 03/05/2014 09:08:13

[robjon44Participant @robjon44]

Hi all, remember well from my motorcycling years when cleaning very heavily soiled alloy engine castings, cut up several large Rhubarb leaves & boil them up in a pan big enough to get the castings in, we naturally got the gear together & did the job over a wood fire at the bottom of the garden, you then have a strong hot solution of Oxalic Acid, that which causes Oak to eat iron nails. They came out clean enough to eat your dinner off, but nowhere as dangerous as Caustic Soda & its ilk. There is also to be considered that one can make a pie out of the red bits the leaves come attached to, if you cant do this find someone who can (no point in having a dog & barking yourself)

robjon44

[Ady1Participant @ady1]

Some of those high pressure water cleaners have a sand blasting attachment

All you need is a bucket of sand

The nozzle has a flexi-tube with a stick-it-in-the-sand alloy tube on the end

**LINK**

[Gordon WParticipant @gordonw]

I use Gunk or similar stuff. Scrub well in and leave for a few minutes, then wash off with water, pref. a pressure washer. This gets the old stuck-on crud off and leaves a nice clean casting to work on. Depends what you want to do with them next. Acetone scrubbed in gets them very clean for painting.

[JAParticipant @ja]

Boil in non-biological washing powder. You will need quite a lot of powder! Do not use detergent or washing up liquid (these are very different).

JA

[GaryMParticipant @garym]

How about car alloy wheel cleaner?

Gary

[RJWParticipant @rjw]

Most alloy wheel cleaners are acid based and just for removing baked on brake dust rather than corrosion, generally there will be a warning on the bottle (if acid based) Not to be used on wheels where the lacquer coating is damaged such as from kerbing etc, it has the same effect on alloy as caustic soda and will turn it black – and it's a bugger to get back to bright alloy again!!

Whichever method is used to brighten the alloy, it will need spraying with something like clear lacquer, beeswax or the dreaded WD40 very soon after cleaning, otherwise the surface will quickly fuzz up with corrosion and need doing again!

John.

[GaryMParticipant @garym]

I'll get me coat.

Gary

[RJWParticipant @rjw]

Only reason i know Garry, is I got caught ……….. as the saying goes 'if all else fails read the instructions ……..' and we all do that don't we!
Some alloy cleaners have no effect on bare alloy and safe to use where the lacquer has been scraped off, just wish they'd make the damned labels and print bigger so you can read them without a loupe to know what you're actually buying!

John.

[peter walton 1Participant @peterwalton1]

Best thing I have found to clean aluminium is boiled rhubarb is also fairly gentle on the ally.

Rhubarb contains some oxalic acid, even more in the leaves, use warm and it will clean off the oxide layer! wash well afterwards.

peter

[Tim StevensParticipant @timstevens64731]

In case it helps someone … the black or grey residue on Al castings when cleaned with alkali (or some acids) is mainly silicon, along with any other alloying elements. And silicon is fairly inert stuff, which is why cleaning is not so easy. The same problem causes some light alloys to look dull or dirty after anodising.

Strong nitric acid is seriously noxious, but can be very useful as it attacks iron and steel but not aluminium. Ideal for removing broken taps or engine bolts that have corroded in place.

Cheers, Tim

[Kenneth DeightonParticipant @kennethdeighton43272]

Thankyou for all of the different solutions, the Rubarb sounds interesting.

Ken.

[V8EngParticipant @v8eng]

Make sure you buy some extra Rhubarb to eat.

Rhubarb Crumble, yum yum!

Edited By V8Eng on 05/05/2014 20:40:07

[“Bill Hancox”Participant @billhancox]

Or rhubarb wine! (Hic)

[Ian S CParticipant @iansc]

You could try something like Frost's Ali Clean, or Wonder Wheels, think it's sold by Halfords. Ian S C

[Toys4boysParticipant @toys4boys]

If castings don't need to be highly polished or have awkward hard to reach pockets, my first choice is vapour blasting. For anything else, I scrub up with neat acetone using a stiff brush and finish of with super fine wire wool soaked in oil or soapy water which gives a nice semi polished finish. Depending on the final result I'm after, I may also buff until they gleam.

If anything just needs a little clean up, I'll use Simple Green diluted with hot water and scrub like mad, then give a good rinse.

[John McNamaraParticipant @johnmcnamara74883]

My preferred methods are:

Ajax or similar domestic cleaning powder and an assortment of brushes from discarded tooth brushes up. water and elbow grease. If there is actual grease strong detergent In Australia called "Domestos" It has a Chlorine base (Sodium hyperchlorate) in solution. applied neat works well.

The Ajax (will) dull polished surfaces So they will have to be repolished later but it is a fairly fine scratch making repolishing with a buff fairly easy.

Do not leave the articles soaking in the strong detergent they will pitted if aluminium and rusted if they are steel, and thoroughly wash and dry all the articles you have worked on. Steel will need to be oiled or it will rust.

If there is a lot of paint you will need to use paint stripper, for aluminium I use a commercial product from the hardware store. And watch it like a hawk I never leave it un attended and risk pitting.

Soaking in Caustic soda / water solution (Sodium Hydroxide) will remove paint and grease very well from steel parts make sure they are completely covered to avoid the exposed part rusting, you can leave them in for a few hours safely. But as mentioned any aluminium attached to your part will disappear! Wear Goggles and Chemical resistant Gloves suitable for strong Alkali, Surgical rubber gloves are useless and will last a few seconds only before disintegrating, and they are too thin, and make sure the proper gloves are in good condition and that they do not have a pinhole that will let the stuff in or you will be burnt. When working with Caustic Soda preferably do it outside. It will eat leather shoes, Wool and a heap of other organic and inorganic materials. Wear protective clothing.

As an alternative you can mix flower into a small quantity of solution of soda until it thickens so it will not run off the part, and paint it on with a cheap plastic (Not bristle) brush, do it is a high sided plastic bin a couple of coats will normally be enough.

Once the soda has done its scrub the parts with a brush under running water. Avoid making a lot of soda solution as disposal requires neutralising the solution with an acid. There a number of links on the net describing how. otherwise take it to the council receiving point in your area.

I have never had to resort to strong acids using these methods.

Regards
John

[Jerry WrayParticipant @jerrywray14030]

John,

Did you really mean to say hypochlorAte?

Jerry

[John McNamaraParticipant @johnmcnamara74883]

Hi Jerry

The Ite's have it, The typo gremlin got me again…….

Sodium hypochlorite it is.

Regards
John

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