Possible overcarbing?

Could be from nucleation sites in the bottle, if you don't clean then well enough, if there are maybe little pieces of hop leaves in there. Any rough site inside the bottle with promote a more rapid release of C02 bubbles when the beer is opened.

 

Are you positive you're letting the beers completely finish out before bottling?

 

Choice of sugar type, assuming you're using appropriate amounts, doesn't cause or prevent gushers, which can really only be caused by three things...

- too much (or unevenly distributed) priming sugar
- incomplete attenuation before bottling
- infection

 

Could be that the beer wasn't done fermenting and yeast fermenting more than just your priming mix will lead to gushers. Could also be an infection where either Brett or a bacteria is in the bottles, and they can eat sugar chains that regular brewers yeast cannot leading to gushers and eventually bottle bombs.

Any off flavors in the beer or just over carbed? Also how much sugar are you using to prime?

Priming amounts also depend on the volume of beer your bottling and I suggest using this calculator when figuring out amounts.

http://hbd.org/cgi-bin/recipator/recipator/carbonation.html?16279076#tag

 

use a scale and a decent carb calculator if you aren't already. measuring priming sugar by volume is not as accurate, after a few batches you should be able to estimate your volume (4.8 gallons instead of 5 for example) and dial in your desired carbonation.

in the meantime, be sure the gushers are very cold before you crack them open as this can help if not eliminate gushing.
Cheers.

 

But do you take gravity readings to be sure?

 

That should be plenty of time. If you have unhealthy or overly floculent yeast it could prematurely fall out of suspension before finishing the beer out. Then when you bottle you might restir up the yeast and it can take off again. I'm sure it's not the problem, especially if you keep an eye on your FG.

 

I always only take two readings and it's rarely steered me wrong. I would always take readings though. Sweet back piece btw.

 

Yea the beers should have finished in those time frames given adequate pitch rates. Sounds like a possible contamination to me. You may have bottle bomb's in your future.

Edit*. Put most in the fridge to keep from exploding if they taste alright and if you wanna find out what's going on put a bottle at room temp in some type of rudimentary bomb shelter.

 

This ^^^^ plus other lesser factors can cause an extended fermentation period that needs to be discovered by those final gravity readings. Being patient means a lot in this hobby.

 

It can take some time for an infection to really show itself. If you like the taste now store as many as you can as cold as you can and drink away!!

 

So, what exactly is your priming process? Do you measure the table sugar by weight? If so, how many ounces (by weight) do you use? What is the volume of the beer that you add the sugar to? Are you able to measure your beer volume?

Cheers!

 

I'd get those in the freezer and drop them to about 30F before opening them. Hopefully that will drop the carbonation into the beer and keep it calm until you can get it into a glass. Otherwise, you can gently pry the top a little and hear a hiss. Back off it and see if the bottle seals back up. If it does, you just removed a little of the pressure and you might be good to go. I'd try this on a small scale before doing all 5 gallons