Gushers

[azazel1024]

So I can't really think of an appropriate place to put this one, but I have a question on gushers.

A couple of times I've brewed a batch the beer was massively over carbed (never had bottle bombs, knock on wood). I've more or less fixed that issue with too much bottling sugar and/or fermentation not entirely finished.

However, a couple of batches I've made over the last couple of years have been gushers, but not obviously over carbonated. IE when opening the bottles there was, what sounded like, a normal amount of CO2 release. However, let the bottle sit there or pour it and all of the CO2 starts coming out of solution, and volcano.

What the heck?

Any ideas what could cause this. It is often an entire batch, but sometimes it is just a couple of bottles of a batch. As I said, it doesn't actually seem over carbonated when poping the cap (at least the headspace isn't under a bunch of pressure) and it also doesn't happen very often (1 of the last 8 batches I've made has had this happen, but seems like it may be the entire batch as the last 3 bottles have all done it). I guess it is possible fermentation wasn't really complete on this one (dopplebock). I ice bathed it for 3 days before I went on vacation and turned the thermostat down to 58F (56F on the slab). Came home 10 days later, turned the thermostat up and it sat for probably 5 days at 64F before I finished converting my minifridge to a fermentation chamber and then laggered it for 2 weeks at 40F before bottling.

Gravity seemed stable when I had checked it and it had reached the gravity range I had exepected it to.

 

[BlueHouseBrewhaus]

Did it taste vinegary? If so, it's an acetobacter infection. If not, the two main sources would be overcarbing, which it sounds like you have already accounted for, or you bottled too soon. Be sure your SG doesn't change for 3 or 4 days before you bottle. If you bottle too soon the beer keeps fermenting and over carbonates. Here's a picture of infected gushers for your viewing pleasure. It was not a happy day. I traced my infection back to the bottling bucket/spigot/wand. I replaced them all and have been fine since.

 

[cjgenever]

One or two bottles it is dirty bottles. All of then means something upstream that contacts all the beer. If it doesn't happen to every batch then it isn't infected equipment, but poor cleaning/sanitation. I visually inspect each bottle and still got an occasional slow gusher until I began soaking then all with pbw the day before bottling. Followed up with high pressure hot water rinse, inspection, starsan via avinator, bottling tree. I also make sure I'm clean and free of things that could fall off me/clothing and wear a mask (non valved) to catch saliva when breathing/talking. I use long gloves. I put a cover over every bottle once turned right side up.

 

[ArcLight]

It sounds like a bacterial or wild yeast contamination.

 

[mark7347]

One or two bottles it is dirty bottles. All of then means something upstream that contacts all the beer. If it doesn't happen to every batch then it isn't infected equipment, but poor cleaning/sanitation. I visually inspect each bottle and still got an occasional slow gusher until I began soaking then all with pbw the day before bottling. Followed up with high pressure hot water rinse, inspection, starsan via avinator, bottling tree. I also make sure I'm clean and free of things that could fall off me/clothing and wear a mask (non valved) to catch saliva when breathing/talking. I use long gloves. I put a cover over every bottle once turned right side up.

My god, then do you perform surgery afterwards? Kudos to you. That's more protection than I'm willing to provide.

 

[Calder]

If you dry hop with pellets, you can get some pellet material in the last couple of bottles if you don't screen it out. The hop material provides nucleation sites for the CO2 to come out of solution.

 

[drainbamage]

Check the bottom of each bottle before you refill. It doesn't take a lot of sediment sitting for a while to get moldy and funk up your next batch. If you find any nasty ones, be sure to soak and clean thoroughly, or just pitch it and replace with a new one.

 

[azazel1024]

I check the bottles each time, and they are quite clean (I chuck the ones that aren't, that and curse at my wife when she doesn't rinse my bottles after pouring a beer).

My standard bottle cleaning method is a check and quick rinse with a bit of water. Then fill with 2oz of water, cap with aluminum foil and then stick them all in my oven at 350F for 60 minutes (often 75-90 minutes because I am lazy and don't go running/don't hear my timer go off). I then pour the water out and bottle the beer once they have cooled (about 2hrs if I am in a rush and open the oven door, up to the next evening if I am sanitizing the night before).

I at least don't think it is every batch. I have had a number have it happen recently.

Both were with Windsor yeast and I was pretty sure that my basement temp dropped too low and the yeast went dormant.

I've had a number of batches that were boarderline too carbed after a few months in the bottle, but they were never really gushers.

With this Dopplebock I was also thinking that the yeast went dormant. That said, the gravity was stable for the 4-5 days that the batch sat at 64F after ice bath/cold basement fermentation (at 56-58F) while I converted my minifridge to lager it. I checked the day I got back from vacation and then 4-5 days later before it went in to the fermentation chamber to lager. 1.022FG and the OG was 1.079 AND I had added a cup of molasses about 5 days in to fermentation (which should have added about .03 to the FG I think). It was White labs bock yeast.

By online math I get 71-73% attenuation depending on how much the Molasses raised the gravity. Which seemed like the right range.

I did just have a bottle blow over the weekend (what is that oddly malty smell in my storage room?). So I went around the batch letting pressure off over 12-18hrs, probably about once an hour for the entire time. I then stuck as much as would fit in my fridge and dumped the 8-9 bottles that wouldn't fit.

Fortunately I also had a party the next day and managed to pawn off about a dozen bottles on various guests who all remarked how awesome it was. So I only have 3-4 bottles left of it (kind of sad). All resonable levels of carbonation now.

So beyond ditching the siphon and tubing, I am also now starting to warm my beers at the tail end of fermentation. Warming them to 68F or so for the lagers and 72F for the ales for a couple of days.

My basement is 64F on the slab from about November-April and hits about 72F on the slab in July/August. Their temp might be a little higher, but that is the temp that the carboy contents actually are (based on many temp probe samples). Until the last few batches (starting with the lagering of the Dopplebock), everything was zero temp control just sitting on the slab.

So I am hoping that my issue all along is that (and it DOES seem potentially yeast strain related) that the slab is just too cold for a lot of yeasts. Initial fermentation is okay (especially because I tend to pitch at around 70-72F for ales and it probably takes 12-24hrs for the carboy to get down to slab temps and they can eat away at the simple sugars first if they want), but as it slows down and it is some of the more complex sugars, some yeast strains go dormant at 64F instead of finishing fermentation.

Those are my only guesses. Not all batches have done it, some seem to have just fine carbonation (especially S05) over the span of several months, some like the Dopplebock and my two Windsor yeast batches were just fine for 4-6wks post bottling, but then noticable and deffinitely got overcarbed till they were dumped/used up (all were killed by 12wks post bottling). I had a few early batches early last year that also had overcarbing issues, but I thought it was mostly related to my "1oz of corn sugar per gallon" stupidity (especially since, depending on the season, bottling at fairly cool temps, so more CO2 in solution already!). I have since moved to table sugar AND using a proper calculator.

Thanks all, and hopefully this is something that I have now resolved (either from replacing bits, or warming the batches at the end of fermentation).