Leaking bottle conundrum

[BigJC]

I've just gone to collect a couple of bottles from my Young's American IPA stash that have been bottle conditioning for well over three weeks and discovered that there was beer in the bottom of the crate (I store them in a plastic crate) Having looked for obvious exploded bottles I couldn't find any however I did find two that were half full. They're Coopers PET bottles, both were fully intact with caps fully screwed on, neither leaked despite squeezing them and the beer inside was fully carbonated and tastes fine. I filled the bottles with water and neither leaked.

I can't for the life of me think how the beer escaped so am wondering if anyone else has experienced similar or can un-blow my mind by explaining how this happens!

 

[cornyandy]

I've never heard of anything like this, my only two thoughts are that either, there has been a lot of secondary ferment activity and the beer has blown through the cap, something I would doubt but it's an idea, or there is a micro fracture in the pet and this has sealed up as the pressure has dropped, even giving them a squeeze would not give as much pressure as a secondary ferment. (Perhaps the leak has gummed up with dried up beer)

 

[Slid]

About two years ago there was an issue with the Coopers PET bottle production line, in that roughly one bottle in five produced had a very small hole in the bottom. Perhaps this fault emerged gradually or is re-appearing?

Can't think of anything else.

Here is an experiment:

Take one of the dodgy bottles and pressurise it by adding sugar to a yeasty solution (or vinegar to bicarbonate of soda, if you are impatient!) and standing the bottle on an absorbent material (newspaper?) and see what happens.

 

[BigJC]

Aargghhh! Another one this morning! I can't be losing beer this way! E-mail to Coopers on its way.

 

[peebee]

Aargghhh! Another one this morning! I can't be losing beer this way! E-mail to Coopers on its way.

Hmm... "another one this morning". That's bad... but your problem might end up going deeper than leaky bottles. Was this one to go on your cornflakes?

 

[BigJC]

I've never heard of anything like this, my only two thoughts are that either, there has been a lot of secondary ferment activity and the beer has blown through the cap, something I would doubt but it's an idea, or there is a micro fracture in the pet and this has sealed up as the pressure has dropped, even giving them a squeeze would not give as much pressure as a secondary ferment. (Perhaps the leak has gummed up with dried up beer)

I sent one of the leaked bottles to the UK distributor for Coopers and they discovered a small crack in the base which they suspect, as you suggested in your post, that the pressure from the fermentation has opened it and then sealed once the pressure had dropped. It would appear that the PET bottles aren't as robust as I would like so I've moved to glass rather than risk losing more beer.