Plastic bottles leaking during secondary fermentation

[mkortink]

I use and reuse plastic 740ml bottles from Coopers and Brew Cellar and have never had a problem. My last batch though has done something weird, 4 of the 30 bottles have leaked most of their contents during secondary fermentation. The bottles were stored upright, there is no crack in the plastic, the lids are on tight, the beer that remains in the bottle tastes good and is not particularly bubbly, BUT there is a big puddle of beer under them. These bottles have perhaps been reused 4 times.

The brew itself was a Canadian IPA from a kit that was 4 months past its use by date. The yeast didn't work so added some I had from another kit and everything went fine from there. I used 1kg white sugar for primary fermentation and teaspoon of white sugar for secondary.

I am mystified, does anyone have an explanation?

Cheers

 

[wbosher]

I've heard there is a weak spot right in the middle of the bottle at the bottom that has been known to spring a leak.

Try capping the bottle with nothing inside and hold it under water while giving it a squeeze, and look for bubbles.

 

[sp0rk]

Are you reusing the same caps or using new ones every time?

Also, stop using white sugar and start using either coopers BE or a body builder blend from you local home brew shop, you'll notice the difference immediately (for the better)

 

[wbosher]

He's only used these bottles 4 times, the caps should last much longer than that. I've been using the same bottles and caps for almost a year and a half and still sealing perfectly.

Definitely agree about the sugar, get rid of that from the primary.

 

[sp0rk]

He's only used these bottles 4 times, the caps should last much longer than that. I've been using the same bottles and caps for almost a year and a half and still sealing perfectly.

Definitely agree about the sugar, get rid of that from the primary.

Fair enough, I was a little paranoid back when I was using PET and always used new caps

 

[mkortink]

Thanks for your replies.

I usually do pretty fancy brews with all the right ingredients, this one was a quick and dirty to get some summer quaffing beer, hence the white sugar (currently doing a Stone & Wood Pacific Ale as per recipe on this website).

I have been using the same caps maybe 4 times tops, for info the bottles that leaked are the Coopers plastic bottles. I have tried to find a leak in the bottle itself by half filling with hot water, shaking to get the pressure up, then squeezing by hand. No liquid or bubbles came out anywhere. The remaining 26 bottles which haven't leaked yet are as tight as drums, but then they always are. If this is a rare occurrence I am guessing the leak came out from under the lid driven by the pressure in the bottle which for some reason was abnormally high. There is no reason for abnormal pressure, I let primary fermentation go for a week in a warm cupboard so there should have been no residual sugar, and for secondary fermentation used a special brewers scoop to get the exact measured amount required for a 740ml bottle. I also note the bottles that leaked were between half and two thirds empty which makes it hard to image how all of that liquid came out of the top of an upright bottle.

Very mysterious.

 

[wereprawn]

I have had this happen on one occasion with a saison. Left it in primary for 2 weeks thinking it would be done and just bottled it without taking an FG. The result was exactly as you described. Always take gravity readings and if your FG seems too high give the fv a gentle swirl or stir with a sanitized spoon. Stalled fermentation then restarting fermentation in the bottle would probably be the problem.

 

[Ross]

It's not the cap, unfortunately there are a heap of these bottles on the market with tiny pin prick holes in them.
Very hard to spot, but you'll end up with exactly what you've experienced.

Cheers Ross

 

[mkortink]

The final SG was 1020 which is pretty high, so I am going to put this down to human error leading to extreme pressure in the bottles due to some primary fermentation sugars remaining during the secondary fermentation, but it is still a mystery where the beer actually escaped from, my guess is under the lid but without blowing the lids off.

Cheers

 

[Pedro6]

Hi all

Have same problem with last 3 brews with Copper Tun plastic bottles. Only a couple of bottles from each brew just lose from half to most of the beer and are still under full pressure when opened except for one bottle which had split on bottom of bottle. Bottles have been purchased progressively over the time I have been brewing so any brew could be in any number of batch of bottles.
I progressed to all grain last August after 12 months or so of kits so presume I have cleaning and sanitation under control as this problem only just started.
The problem bottles feel clean on out side with no obvious sign of beer leaking down the bottle from the top if the tops are the problem.
The only clue I have is one of bottles of stout I bottled 2 weeks ago has a small amount of stout on shelf under the bottle so I am starting to think I have a batch of faulty bottles so will not use any bottle that has this issue again.
My brews have improved greatly with guidance from Martin at local HBS.
Any thoughts or comments greatly appreciated as I hate the idea of loosing (good tasting now after many "average") beers and not knowing why.

 

[Bomber Watson]

This is the reason i sold the 120 odd plastic bottles i had for a six pack and went to flip top glass bottles

 

[superstock]

I had some problems with 740ml PET bottles randomly not carbonating, so I went to glass (mostly swing tops) but I kept about 15 Coopers PET and use 1 with each brew to prove carbonation.

 

[Bribie G]

Hi all

Have same problem with last 3 brews with Copper Tun plastic bottles. Only a couple of bottles from each brew just lose from half to most of the beer and are still under full pressure when opened except for one bottle which had split on bottom of bottle. Bottles have been purchased progressively over the time I have been brewing so any brew could be in any number of batch of bottles.
I progressed to all grain last August after 12 months or so of kits so presume I have cleaning and sanitation under control as this problem only just started.
The problem bottles feel clean on out side with no obvious sign of beer leaking down the bottle from the top if the tops are the problem.
The only clue I have is one of bottles of stout I bottled 2 weeks ago has a small amount of stout on shelf under the bottle so I am starting to think I have a batch of faulty bottles so will not use any bottle that has this issue again.
My brews have improved greatly with guidance from Martin at local HBS.
Any thoughts or comments greatly appreciated as I hate the idea of loosing (good tasting now after many "average") beers and not knowing why.

"Copper Tun" is a fairly cut price range of HB gear that is sold through a lot of LHBS and is a bit inconsistent as it's re-badged stuff from a number of manufacturers.

My LHBS in Taree does a lot of Copper Tun and whilst my 60L FV is top quality when I bought the first lot of bottles from them my first thought was "anything thinner they would be a condom" :blink:

Whilst I try to support the local guy, I do buy a few cartons of PETs a year for competitions and go to Big W for the Coopers original nowadays.

 

[wynnum1]

Had a different brand and a couple of pet bottles had big holes in the bottom.

 

[HBHB]

Hi all

Have same problem with last 3 brews with Copper Tun plastic bottles. Only a couple of bottles from each brew just lose from half to most of the beer and are still under full pressure when opened except for one bottle which had split on bottom of bottle. Bottles have been purchased progressively over the time I have been brewing so any brew could be in any number of batch of bottles.
I progressed to all grain last August after 12 months or so of kits so presume I have cleaning and sanitation under control as this problem only just started.
The problem bottles feel clean on out side with no obvious sign of beer leaking down the bottle from the top if the tops are the problem.
The only clue I have is one of bottles of stout I bottled 2 weeks ago has a small amount of stout on shelf under the bottle so I am starting to think I have a batch of faulty bottles so will not use any bottle that has this issue again.
My brews have improved greatly with guidance from Martin at local HBS.
Any thoughts or comments greatly appreciated as I hate the idea of loosing (good tasting now after many "average") beers and not knowing why.

Drop in next week when you get a chance Pete and we'll sort something out for you. Have 2 other similar reports from afar at the moment. Sounds like a quality control issue to me.