Author Topic: Descaling aluminium?  (Read 4137 times)

Offline AdeV

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Descaling aluminium?
« on: February 06, 2015, 02:04:22 PM »
Hi,

Does anyone know some Really Good Stuff (preferably available in the UK without having to sneak it out of a chemistry lab...) to descale aluminium with? e.g. Sodium Hydroxide would be no good as it'll dissolve the aluminium; Nitric acid might do (I know that fuming Nitric doesn't touch aluminium, but I don't know what effect, if any, it has on limescale)?

Basically, I've been cleaning the water jacket of my Jaguar block with a brass wire brush on the end of a Dremel, and frankly I'm bored to tears. Plus even the Dremel can't get into some of the deeper and less accessible spots, so a really good chemical clean would be a good idea. I've got a Toluene bath ready to do th outside, but that won't touch limescale...

Cheers!
Ade.

PS: it's REALLY important that the aluminium isn't damaged by whatever cleaner(s)....
Cheers!
Ade.
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Offline vtsteam

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Re: Descaling aluminium?
« Reply #1 on: February 06, 2015, 02:40:01 PM »
Can't promise it absolutely will not bother your aluminum, but our espresso maker instructions suggested periodic lime deposit cleanouts with vinegar -- and it's lasted 20 years. It has an aluminum boil chamber. It's run through hot, of course. Smells, but works!
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Offline dawesy

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Re: Descaling aluminium?
« Reply #2 on: February 06, 2015, 03:17:41 PM »
Coca cola is also reported to work.
Or get some cillit bang. That works too. Just test it on a small patch first ;)
Lee.
wishing my workshop was larger :(

Offline awemawson

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Re: Descaling aluminium?
« Reply #3 on: February 06, 2015, 03:35:04 PM »
Well Coca Cola's active ingredient in this respect is phosphoric acid. Cilit bang also has phosphoric acid but quite a bit more:

http://www.wired.co.uk/magazine/archive/2010/08/start/what%E2%80%99s-inside-cillit-bang-power-cleaner

Andrew Mawson
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Offline AdeV

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Re: Descaling aluminium?
« Reply #4 on: February 06, 2015, 04:48:44 PM »
As it happens I have a nice big pail of 76% phosphoric lurking at the back of the shed somewhere, I'll give it a try. If I'm very careful, I should be able to descale most of the water passageways without damaging the block - I wanted to be lazy and just dunk it in a bath full of X for a week & have it come out all shiny & new...

Coca cola - I'd heard that one too (it also dissolves teeth and cleans copper coins...) Cilit Bang is a new one on me (and how disappointing was it to discover that Barry Stark wasn't a real person?), Vinegar - I think I've got a 5ltr of white vinegar knocking about as well...

Hmm, it's a Vee engine, I could use different acids in each bank & report back on results  :zap: :lol:
Cheers!
Ade.
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Offline Manxmodder

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Re: Descaling aluminium?
« Reply #5 on: February 06, 2015, 05:27:29 PM »
Ade, have you tried a powerful pressure washer to see if it will shift the crud from the water jacket?

I've often used a rotary pencil nozzle on a powerful K'archer for cleaning blocks,heads and found it very effective.....OZ.
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Offline RussellT

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Re: Descaling aluminium?
« Reply #6 on: February 07, 2015, 05:43:43 AM »
Hi Ade

It's been a long time since I did chemistry but as I recall.  Aluminium is very reactive - if it is clean enough it reacts with water.  However it's normally coated with oxide which prevents it reacting.

Sodium hydroxide/caustic soda dissolves the oxide so the aluminium is then open to attack.   Most acids don't dissolve the oxide.

The question here is what are you trying to dissolve.  If it's aluminium oxide then I think it's inevitable that anything that's effective will attack the aluminium.  If it's limescale you're probably OK with what you're trying.

If you've got the liners out you presumably have good access to the water jacket.  How about bead or soda blasting.  There are a few web pages describing home made soda blasters.

Russell
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Offline BenH

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Re: Descaling aluminium?
« Reply #7 on: February 07, 2015, 10:38:00 AM »
I have cleaned a Vauxhall 8v head in my phosphoric acid derusting tank before, it removed the scale fine but did darken the Aluminmum quite a bit. But that might be as I forgot it was in there and sat for a couple of days and had been used before for derusting steel, most of it came off with a good jetwash though and the mix was quite dilute. Why not try it on the water pump housing first if that the same and see if it's ok?

Offline AdeV

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Re: Descaling aluminium?
« Reply #8 on: February 07, 2015, 01:41:58 PM »
Thanks chaps, all good ideas - I think the phosphoric sounds like it's worth a try. Ben - trying it on the water pump first is a great idea - that part is sacrificial anyway, as it's going to be replaced with a blanked off item, the water pumps will be external electric ones... thanks for that.

I wonder what sort of concentration would be best... the stuff I have is 76% IIRC, so maybe a 10:1 mix with water... I'll possibly give that a try tomorrow :)

I'm going to have to soda blast the outside, some of the crud is just too thick to shift with solvents, and it's already been jetwashed, and it's stil filthy...
Cheers!
Ade.
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Offline krv3000

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Re: Descaling aluminium?
« Reply #9 on: February 07, 2015, 04:31:29 PM »
hi well this is my tip washing up pawder