Aluminium bottles. A chemistry question

[Wayland]

I have an aluminium water bottle that I'm rather fond of, I think it's possibly German army issue.

It has for some time been the water bottle in my van and as such often is left full for long periods of time. Now it seems to be building up a light coloured deposit on the inside of the aluminium.

Is this likely to be just limescale or is it something else? Should I be concerned at all? and if so how can I safely remove it?

Any answers would be appreciated.

[MartiniDave]

I regularly clean my waterbottles with steradent denture cleaning tablets. I once had a metal flask stain quite badly and dealt with that by using a dishwasher tablet and a kettle full of boiling water, the flask came up as good as new.

A more bush crafty solution might be to use hot water and stinging nettles shaken vigorously. I remember my old mum doing this to clean the bottle my dad used to take his cold tea in when working in the fields all day.

Dave

[twelveboar]

If it is just limescale, you can try vinegar to disslove it, if it is aluminium oxide then it's probably best to retire it from food use. Sigg type ally bottles are laquered on the inside to stop oxidisation, but if it is losing the laquer you'll get a white powdery coating of corrosion. I'm sure that too much of this can accumulate in the body, and has been linked with althzaimers (however you spell it!) disease.

[jayuk]

I had one of those which definetly had a aluminium oxide problem.

Is it one of the German ones with an olive green strip of leather attaching the lid to the main bottle?

Mine used to get a white powdery build-up which when wiped away used to come back shortly after.

If you look at the neck of the bottle you will see the manufacturers initials and the year of manufacture. I guessed it was probably best to stop using a bottle which was 10 years older than I was and was probably poisoning me.

[Wayland]

Is it one of the German ones with an olive green strip of leather attaching the lid to the main bottle?

Yes that sounds like the one, it also sounds like it might be time to retire it too.

Shame really I hate to retire a good bit of kit just because it is getting old, is there any way to clean it and then laquer it I wonder?.....

[Motorbike Man]

Yes that sounds like the one, it also sounds like it might be time to retire it too.

Shame really I hate to retire a good bit of kit just because it is getting old, is there any way to clean it and then laquer it I wonder?.....

There are kits you can get to do the inside of a petrol tank, now I'm not saying you should use the same kit, but if you can do it to a petrol tank, you should be able to do it to a water bottle. I guess you just have to find the right coating material.

[gregorach]

A white powdery buildup which can be easily wiped off probably isn't aluminium oxide, I think... Alu oxide is greyish and sticks to the metal very well. Also, the anodizing process which is used to finish pretty much all aluminum is simply a chemical means of building up a thicker oxide layer. Alu will sponateously oxidise in air in a matter of minutes.

I'd suspect that limescale is a more likely explanation. If it rinses off easily with vinegar, it's limescale.

As far as I know, aluminum itself is more dangerous than its oxide, especially when dissolved in water or inhaled as a fine powder.

If you're worried about alu oxide, don't drink canned beer, don't use tinfoil, and don't use alu mess tins or cooking equipment of any kind. Personally, I'm not that worried...

[demographic]

There are kits you can get to do the inside of a petrol tank, now I'm not saying you should use the same kit, but if you can do it to a petrol tank, you should be able to do it to a water bottle. I guess you just have to find the right coating material.

I think the stuff you are talking about will be PETSEAL but I don't think I would like to be the one who tries it out by drinking fron the container afterwards.

Good for restoring old petrol tanks though from what I hear