Flat bottled beer post-refrigeration - myth or fact

[Malter White]

Hey gang!
After now DIY brewing for almost 3 years using PET bottles, I think I've discovered a pattern to some failures.
On the odd occasion I think we all suffer the odd bottle/screw cap failure and end up with a flat beer.
As they're disappointing to find, especially when you're keen for a drink, I now ensure my bottles are nice and firm before refrigerating but I'm still finding the odd, occasional bottle is failing after refrigeration.
I drink quite steadily and have limited fridge space for long necks so the bottles don't usually sit in the fridge for more than a few days. I'm rather pedantic on rotating the stock ie. first in the fridge gets drank first.
Does anyone have an explanation on whether refrigeration adds pressure inside the bottle or not?
 

[ben 10]

Carbon Dioxide is absorbed by liquids when cold....

[RepSpec]

I think it's a number of factors...

Recipe make up 

Bulk prime efficiency

Secondary fermentation temps (bottle conditioning)

Moon phases

Didn't pray to the beer God's enough...

Ok now it's getting silly .

My last 2 beers, made during lockdown V1, were basic can and be2 brews, with around 200g bulk prime over 23ltrs. These brews turned out good, but lacked a decent head.

They produced very fine, small bubbles that did lace, just not overly dense. But I think it's just a lack of malt/depth in the brews causing it.

All of my beers firm up, perhaps not as much as some have in the past, but are firm. Also, these were made with the Cooper's yeast...

Why did I respond, now im thinking too much about it lol

 

[Malter White]

1 hour ago, Ben 10 said:

Carbon Dioxide is absorbed by liquids when cold....

OK, so does that build pressure in the bottles that will cause the bottles to go soft?

[Malter White]

@RepSpec, I'm sorry I might not have made myself quite clear. The beers are fine generally but the occasional bottle is going soft after refrigeration, when I know they were firm before going in the fridge.

[BlackSands]

8 hours ago, MUZZY said:

Does anyone have an explanation on whether refrigeration adds pressure inside the bottle or not?
 

As Ben suggests, the opposite is in fact what happens.  Pressure lowers. When the beer is chilled the PET's will soften.   My only thought is, based my own similar experiences is that the 'failed' bottles were probably not fully carb'd in the first place.  While they may have felt quite firm to the squeeze when at room temp that is of course a very crude and inaccurate "test" for actual carbonation levels.  

Edited July 29, 2020 by BlackSands

[Malter White]

Oh, OK. I get you now. I was thinking the pressure was building and breaking the screw cap seals but yes, a reduction in pressure would retract things.
Thanks @BlackSands & @Ben 10

[Hairy]

7 minutes ago, MUZZY said:

OK, so does that build pressure in the bottles that will cause the bottles to go soft?

Yep, bottles will go soft. But CO2 is absorbed into the solution so the beer will actually be well carbonated when poured.

Edit: What Blacksands said.

Edited July 29, 2020 by Hairy

[Malter White]

Just now, Hairy said:

Yep, bottles will go soft. But CO2 is absorbed into the solution so the beer will actually be well carbonated when poured.

Yeah, most have been OK to drink but I'd say their carbonation is not optimum compared to the ones that don't go as soft.

[BlackSands]

11 minutes ago, Hairy said:

Yep, bottles will go soft. But CO2 is absorbed into the solution so the beer will actually be well carbonated when poured.

I'm being pedantic but I think it's more accurate to say it will be more carbonated that it might have otherwise been.  But if the overall CO² levels are low, which it sounds like they are in a few bottles, then the beer is still going to pour relatively flat compared to what it should be if fully carb'd.

I suspect there's still an issue to be investigated if the bottles in question aren't fully carb'ing, even though they might feel as if they are.  I've had a few recently where there were lid leaks... but ONLY when the pressure reached a certain threshold which I was able to simulate by squeezing a PET that felt reasonably firm.  I could literally hear gas escaping from the lid.    

Edited July 29, 2020 by BlackSands

[DonPolo]

I've had the odd failure, but at first I put it down to not screwing the cap on tight enough or missing out on putting the sugar in.

So I started being really careful that every bottle got a dose of sugar and using a tea towel to screw them on really tight. .... Still the occasional failure.

Then I thought it might be that some tops have a liner in them and other don't. I was thinking that one might be better than the other. But no, there was still the occasional failure independent of whether the top had a lining or not.

Then the other day I saw a post that said that after sanitising with a solution such as Starsan , you should rinse your FV/bottles out with clean water. The products I have bought in the past said that they were 'no rinse'. however, I had always thought that if sanitisers were designed to kill bugs, why did they not affect the health of yeast cells?

OK so maybe you should let them sit for a fair while so that the droplets dry or run out. But it set me thinking ....

[Journeyman]

1 hour ago, DonPolo said:

however, I had always thought that if sanitisers were designed to kill bugs, why did they not affect the health of yeast cells?

From what I have read in a number of laces, yeast can metabolise starsan and stellarsan. I still reduce the foam as much as possible because I'd rather the yeast work on my ingredients but I don't think that has an effect as far as carbonation goes.

[DonPolo]

3 minutes ago, Journeyman said:

From what I have read in a number of laces, yeast can metabolise starsan and stellarsan. I still reduce the foam as much as possible because I'd rather the yeast work on my ingredients but I don't think that has an effect as far as carbonation goes.

Fair enough. Those flat bottles just seem to be a mystery! 

[Journeyman]

21 minutes ago, DonPolo said:

Fair enough. Those flat bottles just seem to be a mystery! 

I agree. Just before I went to kegs I started getting some - all PET's. I was going to sit down and clip 160 rings off the tops of them as I'd read that was a possible cause but then ScoMo gave me a bonus and I got kegs.

But I had like 20 brews before that and only the last couple started giving me flatties - which was also during cooler weather. I was going to try the electric blanket in the cupboard to keep them warm but again... kegs.

 

[DonPolo]

Yes well kegs are out of my reach at the moment. Living in a two beddy apartment and brewing in a tiny laundry. I'm quite content but space is an issue.

And to be frank, I think kegs would be a danger zone. It's like Dame Edna's view of her 'mother's little helper' the Cardboard Cask .... if you can't see it going down it doesn't count.

[Shamus O'Sean]

4 hours ago, DonPolo said:

And to be frank, I think kegs would be a danger zone. It's like Dame Edna's view of her 'mother's little helper' the Cardboard Cask .... if you can't see it going down it doesn't count.

I tend to agree with this view.  Although I have moved to kegs (apart from a few bottles that I can pass on to friends), it was sometimes helpful to look at the kitchen sink and see the six empty longnecks and decide, maybe that's enough for tonight.

Having said all that Donpolo, once you get to the point of deciding you want and can move to kegging, you will not regret the decision.

Edited July 30, 2020 by Shamus O'Sean

[Malter White]

@DonPolo & @Journeyman my flat bottles aren't due to no rinse sanitiser. I don't use it. I only wash my bottles with sodium perc laundry soaker and rinse.

[Coopers DIY Beer Team]

On 7/30/2020 at 8:01 AM, BlackSands said:

I think it's more accurate to say it will be more carbonated that it might have otherwise been.  But if the overall CO² levels are low, which it sounds like they are in a few bottles, then the beer is still going to pour relatively flat compared to what it should be if fully carb'd.

I suspect there's still an issue to be investigated if the bottles in question aren't fully carb'ing, even though they might feel as if they are.  I've had a few recently where there were lid leaks... but ONLY when the pressure reached a certain threshold which I was able to simulate by squeezing a PET that felt reasonably firm.  I could literally hear gas escaping from the lid.    

Agreed BlackSands, a partial leak would best fit the facts, along with a slight variation: that the particular lid-bottle combination became less gas-tight when chilled, allowing CO2 to escape.   

[DonPolo]

14 hours ago, MUZZY said:

@DonPolo & @Journeyman my flat bottles aren't due to no rinse sanitiser. I don't use it. I only wash my bottles with sodium perc laundry soaker and rinse.

Well goes one theory for my flatties!

[Worthog]

On 7/29/2020 at 11:54 PM, MUZZY said:

Hey gang!
After now DIY brewing for almost 3 years using PET bottles, I think I've discovered a pattern to some failures.
On the odd occasion I think we all suffer the odd bottle/screw cap failure and end up with a flat beer.
As they're disappointing to find, especially when you're keen for a drink, I now ensure my bottles are nice and firm before refrigerating but I'm still finding the odd, occasional bottle is failing after refrigeration.
I drink quite steadily and have limited fridge space for long necks so the bottles don't usually sit in the fridge for more than a few days. I'm rather pedantic on rotating the stock ie. first in the fridge gets drank first.
Does anyone have an explanation on whether refrigeration adds pressure inside the bottle or not?
 

I read all above posts. I had similar problem way back and it is partially the reason I went to glass, then kegs.

1. I felt my PETs were getting old and maybe porous.

2. During winter the bottles were dropping to under 15 or 16c. I believed my yeast, US-05, may have been shutting down and not properly carbonising within the 2-3 weeks.

But you say your PETs are hard when you refrigerate, so, just a heads-up to my situation.

Cheers

[DonPolo]

I've also started to wonder if it is possible to screw the tops on TOO hard. I have started screwing them on really tight using a tea towel so I don't graze my fingers but wondered if this would actually damage the seal.

But then how hard is too hard, and how soft is too soft?

Yes, I also went to bottles but for my latest brew I wasn't sure it was at FG despite waiting a long time and doing some other stuff. So I"ve bottled in PET to guard against explosions. Better a flat one than some glass in an eye!

[Looking Glass]

1 hour ago, DonPolo said:

I've also started to wonder if it is possible to screw the tops on TOO hard. I have started screwing them on really tight using a tea towel so I don't graze my fingers but wondered if this would actually damage the seal.

I brought this same question up with the very knowledgable lady at the LHBS yesterday, whom I was grilling for information for some time, as I've had a number of beers not fully carbonating, she said YES it is possible to tighten too much, the seal can get damaged. I think my overall problem with carbonation at present is just temperature during the second ferment, just a tad too low at the moment is my guess.

[DonPolo]

19 hours ago, Looking Glass said:

I brought this same question up with the very knowledgable lady at the LHBS yesterday, whom I was grilling for information for some time, as I've had a number of beers not fully carbonating, she said YES it is possible to tighten too much, the seal can get damaged. I think my overall problem with carbonation at present is just temperature during the second ferment, just a tad too low at the moment is my guess.

Fair enough. I think there could be a problem, particularly with the bottles that have tops WITH seals. And even the ones without seals, perhaps by screwing them on super tight I might be causing a 'print' of the bottle's mouth to be laid down. We'll see anyway.

•  

[Beerlust]

A long time ago, in a galaxy far, far away...

...back when I first started out & was regularly bottling, I had a few inconsistencies with carbonation levels too. Like most others, I was still buying commercial beer & keeping the empties to use for bottling my home brew stock. My commercial mainstay was/is Coopers Pale Ale stubbies that part way through that period switched to a screw top bottle (from memory). At that time I was purchasing the bulk of my home brew supplies from a single LHBS.

I remember bottling an early batch & quite a number of them were flat after a suitable carbonation period, & I didn't understand why. I thought maybe I missed priming them or I didn't press the crown seals down hard enough. So on the next batch I made sure I primed every bottle & checked each bottle for leaks after capping. Same outcome after they had suitable time to carbonate. Some were barely OK, some were quite flat. 

On the next bottled batch I had forgotten to purchase some bottle caps from my LHBS, so on bottling day I quickly rushed around to the supermarket & luckily they had some of the Coopers crown seal bottle caps on the shelf. So I bottled the entire batch with them. Not a single flat beer from that batch. I was like WTF??.....and then it hit me. It had to be something to do with the crown seal. So I compared the one from the LHBS & the Coopers one. The LHBS one was quite a bit thicker & as such not as malleable as the thinner Coopers one thus it couldn't seal as tightly through the threaded tops of the bottle as the thinner cap could.

I still cap a bottle or two from each batch these days. For sheer reliability & consistency I use a bench capper, crown seal longnecks (no thread), certain thickness malleable caps. No problems with flat beer at all.

Just my 20 cents,

Lusty.

[DonPolo]

Having a look at the Morgans Sanitize  post may interest some people.