Now I am suffering from these tins spontaneously "exploding" and depositing most of their contents over the floor of the cupboard. (6th one today)
The thing is, there's no evidence of a hole in the tin(s)
when I find the offending item, it is obvious because it is lighter than the rest
but it isn't squashy, and none of the liquid remaining in the tin escapes if I tip it over
what gives here?
Presumably you don't mean exploding in the sense that there's a dull thud from the cupboard, and on investigation you find there's a tin split down one side. Were they fizzy drinks? Is the cupboard warm? Has some fermentation taken place? Do the tins look swollen? Not from your description, otherwise you'd be able to identify them immediately without having to heft them. So internal pressure seems unlikely. I assume that the tin has just slowly leaked; possibly a batch of tins with faulty seams. They weren't recovered from Scott's ill-fated Antartic expedition, were they?
Did you have some Gallium in the boot of your car before you scrapped it? If the tins had become contamiated with it the aluminium can will disintegrate slowly - first having micropores that the tin pressurized contents could seep through.
Or do your tins share the cupboard with some mercury - maybe spilled many years ago? That would have a similar effect to gallium and is perhaps more likely to be found in a cupboard.
John
Now that is a theory that I like! But, my recollection of exposed mercury is that over time it "skins over" with oxide. And well dispersed and non-obvious mercury would be in pretty small droplets, wouldn't it convert completely to oxide on the "years" timescale?
Are the failed tins all in contact with the floor, or do tins further up the stack fail? If the latter, I'd be going with Chris's theory about corrosion. I forget whether aluminium cans have an internal lacquer like genuine tin cans.
A few years ago I found a tin of something in a cupboard, that was significantly swollen. I think it was a cooked meat product but can't now remember the details. As it was well within its use-by date, I contacted the mfr who sent a courier to collect it. The mfr replied that the tin had become punctured at some time and contents had got contaminated and started to go off. It was a simple pro-forma reply, because I'd already examined the tin carefully and there was no sign of damage, and anyway how did a punctured tin support sufficient internal pressure to cause it to swell up. I reckoned it hadn't been cooked properly in the autoclave. But as they sent me a few replacements, I didn't bother to take it any further.
I had a few individual tonic waters do that. Strange, I thought, not out of date, just leaked.
Oh yeh, I drive around with a bag of it all the time
tim
only if the cupboard manufacturer contaminated it thus in the factory
:-)
ali
upright
Nope, no split at all
Yup,
Opening what remains of the tin and the usual "pop" of gas comes out
what I can't understand here is why this gas isn't leaking out of whatever hole it was that the first 50% of the fluid leaked out of, leaving the tin limp and squishy
Not especially.
How can I possibly know?
Nope
Physically no different from the others, except that they are lighter
Still have the same solidity from the tin caused by them being full of gas
they don't seem to slowly leak
The pool of liquid occurs very quickly
so why isn't this obvious after the leak?
One thing is, they are a few months out of date, but it's ridiculous to suggest that moulded tins fail over time
I had one out of eight diet coke cans do that, couldn't find where the leak came from on the aluminium can. As someone said, probably a bad folded seam.
This article discusses some of the physics of canning beer. I doubt they would write an article about soda pop like this.
You can also cause the CO2 to leave the fluid by shaking the can. But it settles after a period of time and goes back to equilibrium. In theory, the can is mechanically strong enough for the can contents in either state. Then it's a question of what kind of temperatures it can handle.
Paul
No. Once it skins over it remains protected by an inert oxide coat until you disturb it and then it has to reform. Rather large amounts of spilt mercury were found under a library where a transit instrument used to sit. They used a stone trough full of the stuff to define true vertical!
I'd be surprised if aluminium cans would corrode that quickly without something obvious being visible (were they aluminium? - most are but some beer cans are ferrous). Caustic, washing powder or washing soda might also do for them on the same sort of timescale but I would expect to see obvious signs of white aluminium hydroxide.
so why does only 50% of the contents come out, with the remaining (gaseous) contents keeping the tin firm?
for once
Rod is 100% correct here
>
but the remaining gas is still under pressure
Had a 500g pot of yogurt do that, 18 days within its time-to-go-bang date. White yogurt, white fridge, clean everything just in case.
Typewriters and monkeys...
I kept an emergency tin of condensed 'nestles' milk in the back of the cupboard. By the time it was ten years past its sell by date I opened it out of interest but it had turned into a lump of pale brown jelly. I would have thought the sugar content would have made it keep, but I guess milk proteins don't keep.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.