Compressed PET bottles

[RichieBeer]

What's happened here then?

I've just got this bottle of homebrew from the shed and it's sort of compressed. It's the only one I've seen like that in the batch. All the others have been fine up to now. Is it the cold weather? When I opened it there wasn't much fizz. It's a bit like when you have a bottle of water on a plane and the pressure has made it squashed. Any ideas?

 

[matt76]

I left some empty mineral water bottles in the garage after my last brew, they've done exactly the same in the cold.

Thinking about the physics of it, yes, the change in temperature will do that - like on a plane, exactly as you say (on a plane it's just a change in cabin pressure at altitude, but a change in temperature will do the same thing).

But the carbonation should more then compensate for this - best guess is you use those sugar drops for carbonation at bottling but must not have added one to that single bottle???

 

[terrym]

I use PET for most of my bottles. After filling and priming I squeeze out most of the air that's left in the bottles before capping, and so initially the bottles are slightly distorted inwards. However after carbing up they revert to and keep their normal shape wherever I put them, although they are less pressurised when its cold.

 

[RichieBeer]

Thanks for the reply, I don't use the drops but I do prime each bottle with a teaspoon of sugar before capping. I guess I must have missed one,

 

[Ghillie]

What's happened here then?

I've just got this bottle of homebrew from the shed and it's sort of compressed. It's the only one I've seen like that in the batch. All the others have been fine up to now. Is it the cold weather? When I opened it there wasn't much fizz. It's a bit like when you have a bottle of water on a plane and the pressure has made it squashed. Any ideas?

View attachment 17681

Does it swell up when you shake it?

So that is the only bottle that suffered this fate?