Over Carbonation in Bottle

[Paul_G]

I'm trying to get to the bottom of a problem which has me stumped.  If I brew a light beer such as a wheat beer and bottle condition it then all is well.  If I brew a dark beer such as an oatmeal stout then after two weeks of bottle conditioning all is well but if it's left for a longer period of time then it over carbonates.  Even if I refrigerate it before opening it will gush up after the cap is removed and loose about 2/3 of the contents.  The remaining beer tastes ok so I'm convinced that it isn't an infection.  All my equipment and bottles are well sanitised with Star San.

The malt bill for one batch which over carbonated was:

4Kg of pale malt
0.2Kg of Crystal Malt
0.2Kg of Chocolate Malt
0.1 Kg of Black Malt
0.5Kg of Malted Oats

The mash temperature was 68C (154F) for 90 minutes then a 60 minute boil followed by cooling down to around 20C (70F) through a plate chiller.  The yeast used was White Labs WLP028 Edinburgh Ale.  This was in the primary fermenter for 7 days then transferred to the secondary fermenter for 14 days.  Both primary and secondary fermentation were conducted in a temperature controlled cabinet at 19.5C (67F).  The OG was 1.053.  Gravity after primary was 1.017 and after secondary it was steady at 1.016.  I had 18 litres to bottle so I used 70g of sugar made into a syrup into the fermenter to give a carbornation of 1.8.

After two weeks of bottle conditioning at room temperature I opened a bottle and all was well however a few weeks later it was gushing when opened.  I've tried WLP007 English Ale yeast and 4 weeks in the secondary fermenter but neither solved the issue.

Any suggestions?

[Oginme]

I hate to burst your bubble, but gushers usually result from an infection.  I would open a few bottles and degas the remaining beer before taking another hydrometer reading on the residual.  If it is significantly low, like below 1.010, this is where I would first focus.

Beyond that, you may not be actually reaching your final gravity.  Perhaps the yeast is stalling out and the addition of a little oxygen and simple sugars is causing a refermentation strong enough to reach a lower gravity.  This could explain why you are not picking up any off-flavors.  If you end up with a degassed gravity reading of 1.012 to 1.014, this might be the culprit.

Otherwise, there would not be enough sugars added if you are aiming for a 1.8 vols of CO₂ to cause gushers.

[Ck27]

I hate to burst your bubble, but gushers usually result from an infection.  I would open a few bottles and degas the remaining beer before taking another hydrometer reading on the residual.  If it is significantly low, like below 1.010, this is where I would first focus.

Beyond that, you may not be actually reaching your final gravity.  Perhaps the yeast is stalling out and the addition of a little oxygen and simple sugars is causing a refermentation strong enough to reach a lower gravity.  This could explain why you are not picking up any off-flavors.  If you end up with a degassed gravity reading of 1.012 to 1.014, this might be the culprit.

Otherwise, there would not be enough sugars added if you are aiming for a 1.8 vols of CO₂ to cause gushers.

Most gushers I've made have been accidentally putting too much sugar. Infections do happen but are rare if you sanitize well and boil right.

[Paul_G]

Hi Oginme.

Thanks for that feedback.  I don't have any of that batch left but I have some from an imperial oatmeal stout that I brewed which also has the same problem.  I opened a bottle of it and again it gushed.  This is the third one which has gushed from this batch but the bottles opened not long after the 2 weeks bottle conditioning did not.  The beer was clear with no off smells or flavours.  I measured the gravity of what was left in the bottle and the readings stack up as follows:

Gravity into fermenter = 1.094
Gravity after primary = 1.026
Gravity after secondary = 1.023
Gravity of beer from gushing bottle = 1.020

This has got me wondering if my fermentation stalled and that the sugar i used for carbonation plus the drop of 0.003 in gravity is why it is so fizzy.  If this is the case I need to work out why it only happens to my dark beers.

[Ck27]

Hi Oginme.

Thanks for that feedback.  I don't have any of that batch left but I have some from an imperial oatmeal stout that I brewed which also has the same problem.  I opened a bottle of it and again it gushed.  This is the third one which has gushed from this batch but the bottles opened not long after the 2 weeks bottle conditioning did not.  The beer was clear with no off smells or flavours.  I measured the gravity of what was left in the bottle and the readings stack up as follows:

Gravity into fermenter = 1.094
Gravity after primary = 1.026
Gravity after secondary = 1.023
Gravity of beer from gushing bottle = 1.020

This has got me wondering if my fermentation stalled and that the sugar i used for carbonation plus the drop of 0.003 in gravity is why it is so fizzy.  If this is the case I need to work out why it only happens to my dark beers.

It's possible you woke up the yeast, that seems a bit under fermented.

[BOB357]

I'm with Oginme. Priming for 1.8 volumes, even factoring in a 3 point drop after bottling wouldn't be enough to cause gushers. I really think an infection is the culprit.

I use Starsan exclusively for sanitizing and have never had an infected beer, but have read several post from people I trust who, at least periodically, switch to Iodphor to keep the risk of infections down. Also to sanitize suspect equipment. If your fermenters have scratches and/or nicks they are definitely suspect.

Even if it turns out not to be the problem, an extra thorough cleaning and sanitizing is not a waste of time and may prevent problems in the future.

[Ck27]

I'm with Oginme. Priming for 1.8 volumes, even factoring in a 3 point drop after bottling wouldn't be enough to cause gushers. I really think an infection is the culprit.

I use Starsan exclusively for sanitizing and have never had an infected beer, but have read several post from people I trust who, at least periodically, switch to Iodphor to keep the risk of infections down. Also to sanitize suspect equipment. If your fermenters have scratches and/or nicks they are definitely suspect.

Even if it turns out not to be the problem, an extra thorough cleaning and sanitizing is not a waste of time and may prevent problems in the future.

"switch to Iodphor to keep the risk of infections down."

Why would you do that not like star san would not be good enough, I soak everything in PBW, then soak it with Star San After a good rinse, this just helps with strange odors and keeping stuff from discoloring.

[KellerBrauer]

Greetings Paul_G - I?m going to agree with Oginme and Bob.  However, I would like to ask some questions that may seem obvious, but here goes:

1) Can we assume the batches you have issues with reached their FG?  If not, than they may be completing fermentation in the bottle.  I find it difficult to fathom that 1.8 volumes of carbonation could possibly cause gushers.

2) What are you using to measure gravity?  A hydrometer is the only practical measuring device to use after fermentation has begun.

3) Could the fact that this occurred in dark vs. light beers be a coincidence or could there have been a sanitation issue with the bottles you used for the dark beers?

It?s the dark vs. light thing that?s most perplexing.  I?m leaning toward the dark vs. light as being a coincidence.  I?m also leaning toward an issue with the bottles themselves.

Once you finally figure out what has caused this phenomenon, please share your experience with this group! 

Good luck!

[Oginme]

"switch to Iodphor to keep the risk of infections down."

Why would you do that not like star san would not be good enough, I soak everything in PBW, then soak it with Star San After a good rinse, this just helps with strange odors and keeping stuff from discoloring.

The thought is similar to antibiotic resistance in bacteria.  Using a single type of sanitizer kills teh majority of bacteria which may exist, but a small proportion may survive, even if they are severely diminished in numbers.  Switching sanitizers (assuming they are different types) periodically should help to kill off any bacteria which have become resistant to the attacks of the primary sanitizer. 

[jtoots]

"switch to Iodphor to keep the risk of infections down."

Why would you do that not like star san would not be good enough, I soak everything in PBW, then soak it with Star San After a good rinse, this just helps with strange odors and keeping stuff from discoloring.

The thought is similar to antibiotic resistance in bacteria.  Using a single type of sanitizer kills teh majority of bacteria which may exist, but a small proportion may survive, even if they are severely diminished in numbers.  Switching sanitizers (assuming they are different types) periodically should help to kill off any bacteria which have become resistant to the attacks of the primary sanitizer.

very interesting!

[Ck27]

"switch to Iodphor to keep the risk of infections down."

Why would you do that not like star san would not be good enough, I soak everything in PBW, then soak it with Star San After a good rinse, this just helps with strange odors and keeping stuff from discoloring.

The thought is similar to antibiotic resistance in bacteria.  Using a single type of sanitizer kills teh majority of bacteria which may exist, but a small proportion may survive, even if they are severely diminished in numbers.  Switching sanitizers (assuming they are different types) periodically should help to kill off any bacteria which have become resistant to the attacks of the primary sanitizer.

I always thought that because Star San is acid based that it pretty much would kill anything and nothing could really build immunity. Huh.

[Paul_G]

Hi KellerBrauer,

1) I'm hitting the FG numbers that Beersmith is predicting.

2) I use a refractor along with Beersmith to correct the reading for fermenting wort.  I zeroed it with distilled water and calibrated it against a hydrometer.

3) I always sanitise the bottles with Star San using a vinator to squirt up inside the bottles.  I've even had the problem with brand new bottles which were sanitised.

The same kit has been used for light and dark beers along with the same sanitisation regime.  I've brewed light beers between the dark beers and they've been fine whilst the dark beers have over carbonated.

[Ck27]

Hi KellerBrauer,

1) I'm hitting the FG numbers that Beersmith is predicting.

2) I use a refractor along with Beersmith to correct the reading for fermenting wort.  I zeroed it with distilled water and calibrated it against a hydrometer.

3) I always sanitise the bottles with Star San using a vinator to squirt up inside the bottles.  I've even had the problem with brand new bottles which were sanitised.

The same kit has been used for light and dark beers along with the same sanitisation regime.  I've brewed light beers between the dark beers and they've been fine whilst the dark beers have over carbonated.

You are either using some really really really crazy yeast or are using too much sugar or something sounds way to crazy to be a infection.

[Oginme]

So, just doing a little bit of back of the envelope calculation.  The amount of sugar for carbonation to 1.8 volumes if added to the recipe would give an increase in OG of about 0.001 points.  So, if your gravity at bottling is around 1.023, add a point for the sugar you just out in and you get 1.024.  You are now reading 1.020 so that is a difference of .004 points.  This would give a carbonation rate of about 4.4 volumes equivalent of sugar added. 


Kinda getting into bottle bomb range for standard long necks. 

[Ck27]

So, just doing a little bit of back of the envelope calculation.  The amount of sugar for carbonation to 1.8 volumes if added to the recipe would give an increase in OG of about 0.001 points.  So, if your gravity at bottling is around 1.023, add a point for the sugar you just out in and you get 1.024.  You are now reading 1.020 so that is a difference of .004 points.  This would give a carbonation rate of about 4.4 volumes equivalent of sugar added. 


Kinda getting into bottle bomb range for standard long necks.

Yeah any more and you don't want to be around I've never blown a bottle but I've had some where the cap goes flying like a  bullet when I open them