Coca-Cola corrodes aluminium cans

We had an almost unused case of Coke cans in a cupboard.

We noticed a leak on the floor and opened up the cardboard box.

Some of the cans had corroded and the contents had leaked into the cardboard box.

I contacted Coca Cola.

They were quick to respond but basically said it’s not much of a problem.

The cans “use by” date was Jan 21 so they were 9 months “out of date”.

I disagree, the contents of coca cola are acid, yes, with phosphoric acid but should not eat their way out of an aluminium can (which is coated) in this period of time.

So this is a warning to those who store coke cans in cupboards expecting a long shelf life.


They usually bulge at the top first - then leak…


Hi @Jurek, welcome to the community.

If the can had corroded before useby date (Jan 21), then it would be a concern and would be a faulty product. In such case, it would be possible to get a remedy under the Australian Consumer Law. As the useby date has passed, consuming or storing the product is at your own risk and remedies under the ACL are not possible…

Packaging has its limitations, and in the case of a pressurised soft drink, appears the useby date may be based on the length of packaging intregity. It is worth noting that the corrosion which lead to the failure could have resulted from the outside in, rather than inside out. Humidity, salts or chemicals within the storage area at home can reduce packaging life by causing corrosion on the outside of the can. Aluminium is susceptible to corrosion, and as a can is thin, any corrosion can occur relatively quickly.

Tin (or more correct steel) cans used for a wide range of foods also have a finite life and subject to external corrosion causing packaging failure, spoiling the tin’s contents. This is why one shouldn’t consume and tins/cans with evidence of surface corrosion. They should also be stored in a dry place, free of chemicals or other things which may accelerate corrosion occurring.


For argument’s sake I looked at a few drink cans (various Coke products) and each has a date on the bottom. Small print on the can indicates it is a Best By date, not a use by date. It would seem if corrosion were an accepted problem there would also be a clearer message.

Some of my cans (we don’t drink much Coke product) are a year beyond ‘Best By’ so thanks for raising this. Possibly flat or far enough from top form to not be served. Into the recycle bin they will go.


Even best before can be based on packaging life. Best before doesn’t mean a product has in infinite life. It just gives an indication of the life of a product where quality, nutritional value, colour, flavour etc is still at an acceptable level.

Something I forgot to mention is carbonated beverages slowly go flat over time. Some packaging quicker than others (beer cans cans have significantly less gas the longer they are stored). It demonstrates that the packaging isn’t 100% sealed forever or at the point of manufacture.


The topic subject says it all.
Coke is acidic, and aluminium is a metal.
The process is slow, but eventually there will be corrosion and the container will fail.
So what?

1 Like

Some containers are inherently porous to CO2 under pressure, such as PET bottles, the CO2 will leak out of them over time even if the bottle, cap and seal are perfectly manufactured.

I much doubt that metal cans are also porous to CO2 at the normal pressure used. I can’t think of any way for metal cans to leak other than manufacturing faults (eg failed seam crimping) and that ought to be rare. Do you have any details about beer going flat in cans?


Doing a tour of CUB Yatala a few years ago, they indicated cans will loose gas over time. Asking why, and the answer was twofold.

Crimping can’t get a perfect seal. The surface of aluminium isn’t perfectly smooth causing fissures which leak over time. Contaminants can also sit in the crimp reducing perfect contact getween surface. Some manufacturers use plastic coated tops to try an minimise fissures and have a better crimp seal.

The second is the stamping of the top of the cans, especially to allow the ‘ring pull’ type opening to work, can also cause microscopic fissures. Over time these can leak gas.

Heating and cooling cycles during storage, transportation etc can also increase loss of gas as it can cause fissures to open more over each cycle.

The metal itself is virtually impermeable to gas, but the weakest points isn’t the metal but from crimping and stamping processes.

They suggested that can beer should be consumed within 12 months of manufacture. Soon after purchase is optimum if one wishes a bigger head on their beer. We don’t seem to have any problem meeting this recommendation at our place.


My experience with damaged CCA cans.

Several years ago, I found one sealed can in a 24 carton of Coke which was completely empty.

So much for QA.

I took it to the supermarket service desk and gently tossed it to the staff member to catch, and to her surprise, it weighed almost nothing…

She then claimed that I needed to bring the rest of the carton back for an exchange as they cannot sell individual cans but I manged to explain to her that there would be be no difference between one of their cartons missing a can and my returning a carton, so she went and got a replacement can for me.



I’d be a little concerned about the potency of your choice of Whisky. :shushing_face:
Ethyl alcohol - one recommendation is that it needs to be 60-80% alcohol in solution to be effective. (US CDC)


So are glass bottles a better option for carbonated soft drinks and beer? Especially with the modern upgrade from cork to soft plastic/rubberised seals.

Although cork can be effective.
Vintage champagnes will keep 5-10 years if stored correctly. Non vintage it’s suggested will not last as long.

No further explanation required?

The guide offers limited advice. Apparently it’s ‘Not OK’ to drink champagne out of a mug.

The guide is silent on consumption straight from the bottle. I’d say yes to that, given champagne also comes in a can for convenient consumption as does beer.

Given the discussion on loss of carbonation experienced with Coke and Beers, the same considerations would apply.

1 Like

Maybe. Consider some other aspects of this, how long should you keep carbonated drinks in any kind of container?

If the can stays sound soft drink will likely still be as manufactured after a year or two but why are you keeping it that long? As mentioned above PET bottles are inherently leaky so soft drink in them will eventually go flat with no flaw in the seal or damage to the bottle.

OTOH beer will not be at its best after a year or two. Packaged beer does not improve in the container but degrades, it is made to be consumed soon after it is packaged. I don’t have the talent but experts in the field tell me they can taste the difference between fresh and old packaged beer.

I think a better general policy is to rotate all your food and drink, that is consume the oldest first. I am not talking about vintage wine but even that does not have a limitless shelf life.

There are quite a few accounts on the web of people finding that old drinks in cans are no longer in good condition. A common reaction, as here, is to complain. It might be more sensible to accept that they have a limited shelf life and not to allow cans to get lost in the back of the cupboard or in the shed.


Yes and no. No being corks are a major problem in the wine industry from tainting.

Yes it will be for convenience, but will suffer the same fate as other carbonated canned drinks over time.

@syncretic has summed it up well in relation to why store canned beverages, which are designed to be consumed shortly after purchase and before the ‘best before date’. If one plans to store for a long a time, one might have to ask why


We’re stranded on a deserted island and need to ration our drinks? :laughing::laughing:


I went to a retrieving trial with one of my gundogs some years ago . After I competed , my Brittany bitch came 3 rd , I headed back to the van where I had put a six pack of Carlton Light cans on ice in the esky . I opened the first one and it was as flat as the proverbial s… carters hat . The 2 nd the same , the 3 rd flat too .

Lucky my mates had a few spares to give me . CUB was a customer of our courier company and I did their air freight pick ups from Abbotsford in Melbourne nightly . I showed them the cans that were open and the 3 unopened . They gave me 2 slabs for my inconvenience . I never purchased cans after that . Always stubbies .