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Author: Subject: Cleaning cast aluminum
Miller

posted on 26/5/05 at 03:40 AM Reply With Quote
Cleaning cast aluminum

I have some cast aluminum uprights off a 93 rx7 and they have the usual oxidation on them. I cleaned all the grime I could with some castrol super purple cleaner and it got them clean but the aluminum fought back with a heaping of nasty white oxidation. What can I use to finish cleaning these upright? Im thinkin about sand blasting and then Coating them with something that will prevent the oxidation. Any suggestions? I want to keep them unpainted for crack detection.
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Rorty

posted on 26/5/05 at 04:38 AM Reply With Quote
Some wheel cleaners work OK, but beware; some so-called aluminium wheel cleaners are only for cleaning the proctective laquer or clear powder coating and aren't actually designed to work on bare aluminium.
Dilute caustic soda will clean them spotlessly, but will leave the surface looking grey. A neutralising wash of dilute acetic acid (or ordinary household white vinegar) is needed imediately post caustic wash.
The best method would definitely be to have them bead blasted (not sand) which will brighten them and compact the surface.





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britishtrident

posted on 26/5/05 at 06:45 AM Reply With Quote
Blasting with glass beads or other mild media such crushed chrerry stones.

The other thing you could try is boiling them up in a pan with rhubarb leaves this should get rid of any oxidation.

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Noodle

posted on 26/5/05 at 06:58 AM Reply With Quote
quote:
Originally posted by britishtrident

The other thing you could try is boiling them up in a pan with rhubarb leaves this should get rid of any oxidation.


That is a singularly amusing piece of information. You've made my day.

Neil.





Your sort make me sick

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Rorty

posted on 26/5/05 at 07:01 AM Reply With Quote
quote:
Originally posted by britishtrident

The other thing you could try is boiling them up in a pan with rhubarb leaves this should get rid of any oxidation.

Now that you mention it, any time we used to cook rhubarb in an aluminium pan, the pan was imaculate up to the level of the rhubarb. I suppose the same acid is present in the leaves as in the stems.
Is rhubarb the only edible aluminium cleaner?





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NS Dev

posted on 26/5/05 at 07:14 AM Reply With Quote
The odd thing though Rorty, and I don't know why, but as you said, alkalis clean alloy, acids don't normally seem to touch it, but then rhubarb does????????????

I used the dilute caustic method prior to making my blaster.

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britishtrident

posted on 26/5/05 at 07:51 AM Reply With Quote
The leaves contain a much higher concentration of oxalic acid and nephrotoxic acid so much that they are highly poisionous.

The other acid that is used for cleaning aluminium alloys is Phosphoric acid --- aka rust remover Naval Jelly, Jennoite.

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longwayoff

posted on 26/5/05 at 07:56 AM Reply With Quote
No its not rhubarb leaves are toxic. They contain high levels of oxalic acid and its nasty stuff. Effects of poisoning vomiting diarrhoea, prevents blood clotting, permanent damage to digestive tract, Oh yeh and death. It can enter the body through skin contact or by inhalation and you don’t need much as little as 5g will kill you so boiling rhubarb leaves is a bad thing
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Rorty

posted on 26/5/05 at 08:09 AM Reply With Quote
quote:
Originally posted by longwayoff
...as little as 5g will kill you so boiling rhubarb leaves is a bad thing

There's nothing dangerous about boiling rhubarb leaves, as long as you don't ingest any of it. So cleaning aluminium parts in it would simply require some common sense.





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JonBowden

posted on 26/5/05 at 10:23 AM Reply With Quote
As a possibly safer option, I have found that most household cleaners that warn you not to use them on aluminium are good for cleaning aluminium. I have used Flash many times to clean aluminium engine parts (after de-greasing with Gunk or similar)
Oven cleaners are good (try on a sample first)

[Edited on 26/5/05 by JonBowden]





Jon

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flak monkey

posted on 26/5/05 at 11:12 AM Reply With Quote
quote:
Originally posted by JonBowden
As a possibly safer option, I have found that most household cleaners that warn you not to use them on aluminium are good for cleaning aluminium. I have used Flash many times to clean aluminium engine parts (after de-greasing with Gunk or similar)
Oven cleaners are good (try on a sample first)

[Edited on 26/5/05 by JonBowden]


The reason they say dont use it as they dissolve the aluminium, albeit a small amount. The chemical reaction will give off some nasty fumes, so just do it outside.

How about that Cillitbang stuff? Works on copper, and would prob work on ali too.

If you want it sparkly then most of the ways mentioned will acheive what you want by dissolving the top layer of the ali oxide on the casting. (Some methods being safer than others)

Incidently theres not much that reacts with Al2O3 as many people have found, its also pretty hard stuff being a ceramic.

Alternatively just get them glass bead blasted. Shouldnt cost you much and they will come back spotless.

David





Sera

http://www.motosera.com

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Jeffers_S13

posted on 26/5/05 at 11:45 AM Reply With Quote
Without any question the best way is aqua blasting, its glass beads carried in very high pressure water I have had lots of aluminium bits done by a motor rewind place litereally next door to where I work, he did me loads of bits for £10. They cam up like new, I have told everyone about it ! I'll put a pic in my archive. You can see what it looked like before in the 'my fabbed manifold' pic.

[Edited on 26/5/05 by Jeffers_S13]

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longwayoff

posted on 26/5/05 at 11:58 AM Reply With Quote
Believe me Rorty boiling rhubarb foliage is dangerous. Oxalic acid can enter the body through contact with the skin; it can be inhaled it can cause serious burns to the eyes if inadvertently splashed into them. Even low-grade very dilute oxalic acid is dangerous stuff. However quickly becoming one of the more common ways of doing yourself serious harm these days would appear to be using paint strippers that contain Dichloromethane or sometimes called Methylene dichloride or Nitromors “It’s a bit slow, so you get out your hot air gun or fan heater, just to speed things up and there you go phosgene gas and your dead” I have had five incidents reported to me this year alone in our region. In every case it been fatal and its involved a chap in his garage or garden shed.
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ned

posted on 26/5/05 at 11:59 AM Reply With Quote
have seen demos of a company that makes machine to do blasting with dry ice, seemed very effective from what i saw, thogh don't have any info on cost, as useless as a solar powered torch really





beware, I've got yellow skin

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NS Dev

posted on 26/5/05 at 12:10 PM Reply With Quote
quote:
Originally posted by Jeffers_S13
Without any question the best way is aqua blasting, its glass beads carried in very high pressure water I have had lots of aluminium bits done by a motor rewind place litereally next door to where I work, he did me loads of bits for £10. They cam up like new, I have told everyone about it ! I'll put a pic in my archive. You can see what it looked like before in the 'my fabbed manifold' pic.

[Edited on 26/5/05 by Jeffers_S13]


That looks superb!!!!!!

Where in coventry is the place?? I am near Hinckley so not too far away, may need to get a few bits done!

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Jeffers_S13

posted on 26/5/05 at 12:16 PM Reply With Quote
I actually work in Warwick, the place I used is call GEM Rewinds. They just happen to have an aqua blaster which I found out through another guy I use for my aluminium welding, in fact he installed it. As I say they are next door to where I work (Cape Engineering) its a 'call in and ask for so and so' type job though, dont go ringing up. Just go into reception and ask for John Dwyer. Prolly wise to mention that I told you about the place or he'll wonder who the hell you are (!) not that he knows me name or anything but Ive been there a few times now so he sort of knows me.

You'll have to call in and see some of the other bits I had done, if you bring what you want blasted I'll get them done the next day at lunchtime. I live not far from Coombe Abbey, let me know and I can U2U some directions etc.

James

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locogeoff

posted on 26/5/05 at 12:21 PM Reply With Quote
We used to boil bike engine casings in a washing up powder solution to bring them up lovely

[Edited on 26/5/05 by locogeoff]

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Rorty

posted on 26/5/05 at 01:39 PM Reply With Quote
quote:
Originally posted by longwayoff
Believe me Rorty boiling rhubarb foliage is dangerous. Oxalic acid can enter the body through contact with the skin; it can be inhaled it can cause serious burns to the eyes if inadvertently splashed into them. Even low-grade very dilute oxalic acid is dangerous stuff. However quickly becoming one of the more common ways of doing yourself serious harm these days would appear to be using paint strippers that contain Dichloromethane or sometimes called Methylene dichloride or Nitromors “It’s a bit slow, so you get out your hot air gun or fan heater, just to speed things up and there you go phosgene gas and your dead” I have had five incidents reported to me this year alone in our region. In every case it been fatal and its involved a chap in his garage or garden shed.

I'm aware of the dangers of oxalic acid; I used it regularly in a saturated solution.
I just don't think it's a problem for people to clean parts in boiled rhubarb leaves if done sensibly.





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britishtrident

posted on 26/5/05 at 07:43 PM Reply With Quote
As Rhubarb leaves are only 0.5% oxalic acid You would need to eat around 5+kg of rhubarb leaves to kill yourself ok a lot less than that will make you ill --- but I don't think boiling them up is going to be a unleashing a WMD
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britishtrident

posted on 26/5/05 at 07:44 PM Reply With Quote
You can get blasting attachments or ordinary pressure washer -- it works quite well if messy.
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Liam

posted on 26/5/05 at 11:34 PM Reply With Quote
Back in my days of homebrewing, I once sterilised a load of stuff in an aluminium saucepan. The pan came up immaculate afterwards thanks to the bruclens steriliser! Chlorine based I think.

Liam

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Miller

posted on 27/5/05 at 01:04 PM Reply With Quote
Ill just bead blast them. I have the setup to do it but im mainly concerned about what to coat them in to prevent the parts from re-oxidizing. I was gonna use a clear gloss made by por-15 that seems pretty tough. Are their any aluminum specific clear coates out there that you guys have tried?
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Rorty

posted on 27/5/05 at 01:30 PM Reply With Quote
Yes, I have some of my polished, spun aluminium wheels sealed with a clear powder coating specifically for the job. Any good powder coaters would be able to advise you.





Cheers, Rorty.

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JAD

posted on 27/5/05 at 05:01 PM Reply With Quote
Cleaning cast aluminum

Anodize processors use a chemical called "de-smut" which is ferric & sulfuric acid. This stuff will leave the surface spotless and very silvery. Be careful with media blasting the surface as any surface discontinuities will be peened shut.

John

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