Random inexplicable overcarbonation - any ideas?

[Beervis]

Hi team,

 

I've finally gotten around to drinking this Vintner's Lager recipe pack I did a while back:

 

1 x 1.7kg Thomas Coopers 86 Days Pilsner

3 x 500g Coopers Light Dry Malt

1 x 250g Caramel Hell Grains

1 x 25g Nelson Sauvin Hop Pellets

1 x 25g Enigma Hop Pellets

1 x 11.5g Saflager S-23 Dry Yeast + kit yeast

1 x 250g Coopers Carbonation Drops

 

Only alterations I made to the orig recipe was to use half the hops @ 5 mins and the rest at flameout instead of dry hop. I left it in primary around 15 degrees for 2 weeks but didn't CC.

 

Anyhow, the issue is, a bunch of the PETs are rock hard gushers, some so bad that the base of the bottles has blown out to the point where its almost cracking and won't stand up, then a few of them are flat. This isn't the first time I've had issues like this, although the worst previous 2 were with 3 carb drops, and the other with commando dry hop which I thought explained it.

 

I was happy with the SG and fermentation looked to have finished a while before I bottled. I only used 2 carb drops so shouldn't be an issue there.

 

My theories so far: 1) lagering too long at room temps? and 2) maybe old PET bottles?

 

In terms of taste, once I leave it to sit open on the bench for a while it's a really nice drop. I'm wanting to move to all glass bottles soon though and issues like this make me wary of bottle bombs.

 

Paul

[ben 10]

Several possibilities.

 

Fermentation not finished.

Infection.

Too many particles in the beer - form nucleation points, ie help the carbon dioxide come out of solution.

Not left in the fridge long enough before opening.

[headmaster]

What Ben said however the infection/contamination would lead to a funky/sour taste, also gravity would be way down possibly near 1.000.

 

I'd say due to bottle damage, fermentation was not finished, or yeast stalled.

 

If you know your FG before bottling, degas a sample and read the gravity now.

 

0.004 is the same as two carb drops. So if you read say 1.014 at bottling time and it's now 1.010, it's like you have added 4 carb drops.

 

Before cold crashing I have learnt to leave all beers for at least 10 to 12 days, even if fermentation is finished in 2 to 3 days. I wait until the krausen has fully dropped back in to the beer as well.

 

 

[ChristinaS1]

 

I was happy with the SG and fermentation looked to have finished a while before I bottled. I only used 2 carb drops so shouldn't be an issue there.

 

Hi Beervis. What exactly do you mean by this? What was your FG? How many days after pitching did you bottle?

 

 

My theories so far: 1) lagering too long at room temps? and 2) maybe old PET bottles?

 

In terms of taste' date=' once I leave it to sit open on the bench for a while it's a really nice drop. I'm wanting to move to all glass bottles soon though and issues like this make me wary of bottle bombs.

 

Paul [/quote']

 

If you let the bottles sit at room temp, that is not lagering. But just out of curiosity, how long did you leave them before sampling?

 

Since only certain bottles are affected, I would think it has something to do with the bottles. Option 1.) maybe some bottles are contaminated, or Option 2.) the batch was not finished when bottled and some of your bottles are leaking air, and some are not. If the over-carbonated ones taste the same as the ones that aren't, that would suggest Option 2.

 

You say you did not CC, and you don't mention fining. Do the over carbonated bottles have more hop matter in the bottom? I suppose that is a third possibility.

 

Cheers,

 

Christina.

 

[jackgym]

The only time in the past I've had over carbonation was when I brewed using 1.5 kilo of LDM with the can (such as with Bootmaker) instead of just the 1 kilo.

 

Lately it's only happened when I dry hop (commando and wrapped in a chux wipe). Not exactly gushers but half a glass of froth.

 

On both occasions I brewed kit beer with PET bottles and 2 carb drops.

[Beervis]

Thanks for your replies everyone.

 

A few things: Unfortunately I didn't write down my FG. Just remember it being in the suggested range for the recipe. I've had off readings before though so I wouldn't be surprised if that was part of the problem. Also I didn't let the temp rise at the end to finish off the fermentation as I've heard you should do with lagers.

 

It doesn't taste infected so I'm guessing the fermentation was stalled or incomplete. I always leave primary for 2 weeks though regardless of the FG and how the beer looks so I thought I was safe there.

 

Christina, I brewed the batch on 22nd Jan, bottled 5th Feb and tasted a couple tallies on 12th March. The funny thing is they were fine then, it's only today when I went back to them that they're really overcarbed. Just checked my second carton and they are all rock hard. Like you say chucking them under the stairs isn't 'lagering' so I'm wondering if my ambient temps are too high and they should've all gone in the fridge after 5 weeks. Oh for more fridge space!

 

Only 2 of the bottles were flat so I'm putting that down to those two leaking air.

[Beervis]

The only time in the past I've had over carbonation was when I brewed using 1.5 kilo of LDM with the can (such as with Bootmaker) instead of just the 1 kilo.

 

Lately it's only happened when I dry hop (commando and wrapped in a chux wipe). Not exactly gushers but half a glass of froth.

 

On both occasions I brewed kit beer with PET bottles and 2 carb drops.

 

I've had the same issues there too, with the dry hop, although it doesn't tend to be every bottle just a few really bad ones and most ok. This time it's different they are all overcarbed except for a couple of dud bottles that went flat. I've had the opposite problem too where the whole batch was good at 5 weeks then all of them bar one were flat a month later. It only ever seems to happen with lager yeast.

 

 

[Otto Von Blotto]

I think your blanket two week timeframe before bottling regardless of the batch, FG etc. needs to go. In some instances it's too long (though it won't harm anything), and in some instances it may be too short. This instance could be the latter. It shouldn't take two weeks even for a lager yeast to reach FG, but it may have been slow for some reason. Bottle/cold crash according to when it reaches FG plus a few days, that's all it really needs. Anything longer is just wasted time really. I've been using this method for years and it's never failed me once*.

 

It should also be noted that there is a difference between overcarbonated beers and gushers. While they usually tend to go hand in hand, sometimes a normal carbed beer will still gush out of the bottle if it isn't cold enough or there are particles in the bottle that provide nucleation sites for the gas to form bubbles on, although if the beer is cold enough then this effect is reduced. At the same time, an overcarbed beer may not gush out of the bottle upon opening.

 

I don't think storage temp is your issue. That won't cause it to carbonate more. The only thing that will affect the carbonation level is the amount of sugar that gets fermented in the bottle. I'd done plenty of lagers in the bottle prior to getting kegs that never behaved like that either.

 

*I had two bombs in a batch of porter about 4 years ago, using S-04 yeast. It looked like it had reached FG, was in the expected range so I bottled it and a month or so later there were a couple of explosions. The rest of the bottles were way overcarbonated for the style as well. It's unfortunate because that yeast was a winner in that recipe, but now that I'm kegging and don't have to worry about bombs, I'll probably go back to it for that beer when I do brew it.

 

Cheers

 

Kelsey

 

 

[headmaster]

You can of course easily let pressure out of the PET's, just carefully unscrew the lid and screw back up before anything comes out. A bit of work however, as you may need to do that maybe 3-4 even 5 times over say 5 days at room temp to reduce the co2 back to normal levels.

What temp did you ferment the lager at and what yeast?

[ChristinaS1]

Thanks for your replies everyone.

 

A few things: Unfortunately I didn't write down my FG. Just remember it being in the suggested range for the recipe. I've had off readings before though so I wouldn't be surprised if that was part of the problem. Also I didn't let the temp rise at the end to finish off the fermentation as I've heard you should do with lagers.

 

It doesn't taste infected so I'm guessing the fermentation was stalled or incomplete. I always leave primary for 2 weeks though regardless of the FG and how the beer looks so I thought I was safe there.

 

Christina' date=' I brewed the batch on 22nd Jan, bottled 5th Feb and tasted a couple tallies on 12th March. The funny thing is they were fine then, it's only today when I went back to them that they're really overcarbed. Just checked my second carton and they are all rock hard. Like you say chucking them under the stairs isn't 'lagering' so I'm wondering if my ambient temps are too high and they should've all gone in the fridge after 5 weeks. Oh for more fridge space!

 

Only 2 of the bottles were flat so I'm putting that down to those two leaking air.[/quote']

 

Yes, I think you are correct and your fermentation was incomplete when you bottled. The fact that they were fine back on March 12 and only became over-carbonated later supports this theory. Probably if you had increased the temp in the FV to 20C for a couple of days at the tail end of fermentation, you would have been fine.

 

It is recommended that bottles be stored at 20C initially, during the carbonation phase, and then be stored cooler, if possible. If you chucked them under the stairs immediately, and the temperature is a little cooler there, the carbonation phase may have taken a little longer than it would have at 20C...If it is not possible to store them cool after the carbonation phase is completed, storing them warmer should not lead to bottle bombs, that is if the brew was finished before you added priming sugar.

 

As someone who bottles in glass myself, if fermenting below 20C, whether ale or lager, I always increase the temp to 20C for a couple of days, at the tail end of fermentation, as a bottle bomb prevention measure. If you ferment your ales at 20C or higher, this step it is not necessary.

 

I have never had a bottle bomb. Had one close call, but that batch was infected. I opened them very carefully, in full protective gear, and dumped them.

 

Cheers,

 

Christina.

 

 

[Beervis]

This batch (Vintner's Lager ROTM) ended up being really nice after a couple days in the fridge.  Definitely overcarbed but pouring slowly/leaving the bottles open on the bench for a while did the trick.  The pilsner flavour matched with Nelson Sauvin is really decent.  

Since I've had a few issues with this in the past I'll definitely be following Otto's advice and paying closer attention to my gravity readings rather than just waiting an extra week and bottling.   In the process of doing this with my current batch, I've discovered my hydrometer is way out, it's reading 6 points low in room temp water, so I've had to adjust my readings.  Current batch is definitely still fermenting post 1 week despite looking finished so glad I'm paying closer attention to it.

Christina, I live in the sub-tropics so cellaring the bottles at 20c is never an issue even in winter, generally at least.  Storing them cool is more of an issue since 3 fridges in a small townhouse would be pushing my luck with the other half   

I'm moving to all glass bottling soon so I can age beers a bit better, I've had a huge excess stock of experimental brews in plastic and I've found that PETs are unreliable after the 6 month mark.  Some batches have been fine, had one batch all go flat bar one bottle, and other batches where 2 or 3 of the bottles are dud after that long.  I'm not noticing any marked improvement in flavour either so I figure glass is the go.  

Cheers,

Paul