Homebrew: beer foams wildly out of bottles when opened?

Question

I've recently bottled my third batch of homebrew- this was a strong ale, mini-mash. It fermented in the primary fermenter for two weeks and then was transfered to the carboy for an additional three+ weeks, at which point the finishing gravity was at an expected value. I bottled the five gallons with .75c of priming sugar, as before, and everything went smoothly.

At about two weeks and then four weeks after bottling, I opened test bottles to check the progress. Both bottles were among the last to be bottled in this batch and both were completely still- they hadn't been moved in two weeks. When I opened both at room temperature, foam poured out of the bottles in great amounts, and continued to do so for about 60 - 90 seconds. The remaining beer was relatively well carbonated.

What could have caused this phenomenon? As stated, the finishing gravity was as expected (1009) and the beer had been completely still for several weeks.

Answer 1

Two possibilities. If you are lucky, you did not ferment to completion. Reaching a particular final gravity is not proof that you have beer ready to bottle. Always let your beer go until the airlock is no longer bubbling and then test SG. When it remains constant for three days, you have finished fermenting. FG may be higher or lower than the target.

The other possibility is that you have bacterial contamination. If so, there will be crud in the necks of the bottles.

I trust that nobody sneaked in and shook up the bottles before you opened them.

Open the rest when they are cold and do it over the sink.

Answer 2

I would recommend visiting the BeerAdvocate.com, they have a very active home brewing forum where plenty of experienced brewers can help you.

Answer 3

With my first batch of beer I had the same problem. I know .75c of priming sugar is considered standard, but I felt that the only explanation could be that I over-primed. Hopefully someone else will have a better answer for you.

As for the batch already in bottles, open it over the sink when serving and immediately pour into a glass. Once it's out of the bottle, the uncontrollable foaming stops so you can still enjoy the fruits of your labor.

Answer 4

even tho your finishing gravity was what you expexted the there was still more risidual sugar than you expected or...

as I found once

even only 3/4 cup priming sugar can be too much.

after moving from promary to secondary fermenters and then bottleing you will have less than 5 gallons. you need to take that into consideration when calculating your secondary priming. ales typically have a lot of fall out or residue when fermenting ( ales are faster than lagers)

hope this helps