Inoxia
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Very tough limescale
Hello all!
I have finally decided to clean my aluminium waterbath (which i have had for years). It has a very nasty limescale rim towards the top of the bath,
less so furthur in.
I have tryed using commercial citric acid based product to remove the limescale however this had very limited success. I kept the citric acid in the
bath for about half an hour at around 80degC but it didnt remove the scale.
I also tryed a liquid limescale remover which doesnt mention what chemical it uses but is in the form of a liquid pouch- still no success.
Could somebody reccomend a chemical which will remove this well without destroying the Al bath, ie, HCl is out.
Will nitric work?
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chloric1
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If you use nitric acid make SURE it is concentrated so it immediately passivated the aluminum. If there is ANY copper present, this could counteract
the passivation. Not sure though. If you can wait a few days, I know a seller on ebay that sells tetrasodium EDTA. Also, phosphates like sodium
tripolyphosphate, hexametaphosphate, or pyrophosphate.
Fellow molecular manipulator
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Ozone
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Your treatment(s) whould have worked well on lime and/or carbonate scales. I suppose you could try CLR, but if citric acid did'nt work, I suppose that
gluconic probably won't, either.
Sounds like you might have caked-on alumina/aluminum hydroxide. I have seen this before at the liquid:air interface in other aluminum vessels.
FYI,
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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merrlin
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If the scale is thick enough, heating the aluminum to a few hundred degrees Celsius might cause the scale to spall off due to the mismatch in thermal
coefficient of expansion. Perhaps a torch applied to the exterior surface.
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Inoxia
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Using conc HNO3 in it might be a little OTT so i will try 10% methanoic acid (to dissolve CO3-) as reccomended in the instruction booklet i have just
found.
If it is Al(OH)3 that is a problem... I can remove the waterath from the elements and heating it would ruin the electrics inside so the thermal method
is out. Is there anything which will dissolve the hydroxide and not the metal?
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zed
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Chemistry is beautiful, chemistry is exciting, but chemistry may not be the answer to your problem.
Al2O3, is not readily soluble. And, it isn't very reactive. I suggest you abandon chemistry, and resort to applied physics.
Scrape the majority of your crud off, with a paint scraper, and sand the rest off.
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Ozone
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ROTFLs...
Be careful with the application of scritchy physics. Sometimes, corrosion of this type might be deeper than you think. Be careful not to perforate the
vessel. If you get "in there" a bit and there is still more, it might be wise to consider whether a water-tight yet cosmetically-challenged bath is a
better deal.
Cheers,
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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franklyn
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Aluminum cleaning
http://www.howtocleanstuff.net/house/surfaces/how-to-clean-a...
As described above , elbow grease is the time honored method used by
house wives worldwide. If you do not have a house wife available the
desired result is guaranteed if H O T lye ( sodium hydroxide ) is applied ,
it will however erode the aluminum surface slightly.
Aluminum car wheel cleaners are not as harsh , but stay away from those
intended to polish , containing only oxalic or glycolic ( hydroxyacetic ) acid ,
they are mild in action.
Wheel cleaners which contain fluorine are effective , do not be careless
with these , they W I L L leave lasting discoloring burns on your skin.
In order of increasing lime descaling effectiveness :
http://hpd.nlm.nih.gov/cgi-bin/household/brands?tbl=brands&a...
http://hpd.nlm.nih.gov/cgi-bin/household/brands?tbl=brands&a...
http://hpd.nlm.nih.gov/cgi-bin/household/brands?tbl=brands&a...
http://hpd.nlm.nih.gov/cgi-bin/household/brands?tbl=brands&a...
.
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