I recently brewed the Brewer's Best Milk Stout, which uses LME plus lactose and maltodextrin. The original gravity was 1.060, which is within the specs for offered in the instructions. Now after about 1 month in secondary, the beer is is holding steady at 1.030, which is apparently too high (specs indicate 1.020 - 1.024). I'm nervous to bottle in case they will explode.

I tried adding some dry ale yeast (Safale US-05) to try and kick the fermentation on, and even added a little heat with a brief water bath, but after one week there is no change. Furthermore, the room im fermenting in ranges from about 65-70 degrees, so it seems unlikely to have become stuck from low temperature. Also, the beer tastes fine right now, but I don't have the experience to tell whether it's "too sweet".

Two potential issues come to mind. First, I spaced out and failed to add the lactose and maltodextrin to the boil -- they were added just before racking into the primary. Perhaps these non-fermentables didn't see as much conversion to fermentables as they might have? Second, I may not have used a temperature conversion for the original gravity, so perhaps the OG was actually higher than 1.060, and the 1.030 really is indicating a greater amount of non-fermentable sugar than I am expecting?

What should I do? I'm tempted to just bottle it, since my hunch is that the high FG indicates a lot of non-fermentables, but perhaps I should try adding some more yeast of some kind? What kind?

  • 2
    If it does not change in your fermenter, it won't change in the bottle either. It's safe to bottle.
    – Robert
    Commented Jan 26, 2017 at 23:04

4 Answers 4


I can tell you from experience that a high FG can end up causing bottle bombs. My last batch had an FG of 1.020, down from an OG of 1.064. I let the beer sit in primary for a few weeks, but the FG stayed steady. Even after transferring to secondary, the FG held at 1.020, so I assumed the beer had finished. I bottled with less than the usual amount of priming sugar, and within three weeks, I had bottle bombs and gushers.

My hypothesis is that the priming sugar gave whatever yeast was in the bottles enough of a kick to restart fermentation in the bottle; the yeast then consumed the remaining sugars in the beer, which sent the carbonation much higher than it would have been with just priming sugar.

I would assume that something as high as 1.030 is an indication of a stuck fermentation, and that you should try unsticking it: swirl the beer to add some oxygen, raise the temperature, pitch more yeast, etc. In my case, I was off by 0.010, which is a bit more than the 0.060 you missed by. Personally, I would err on the side of caution - bottle bombs are extremely dangerous. I've had one explode by my face; it's not something you want happening to you!

  • Waiting about 1 week after pitching the second round of yeast, the fermentation started up again, like a storm. I week later, the FG is down to 0.020, right where it should be for a milk stout. Time to bottle now!
    – tef2128
    Commented Feb 3, 2017 at 16:01

If you've done all that, I don't think you need to worry about bottle bombs. Lacto and malto are non-fermentable, long sugars which give this beer its body. And that is what is expected in this beer style. I'd bottle it.


If it's staying the same, you are probably fine... But 1.030 is really high for a 1.060 beer so I'd keep an eye on it. That said, being .006 off of your expected gravity is not completely strange, esp. if your starting gravity was higher than you expected. I'd be more worried about it being too sweet than I would be about bottle bombs.

For what it's worth, a pound of sugar will add about .008 to your gravity reading for a five gallon batch. So if you put a pound of unfermentable sugar in there, you could expect your finishing gravity to be about .008 higher than it would be otherwise.


My experience is that with a higher ABV, you will loose the yeast that carbonates the beer. The alcohol will kill your yeast for bottling. I do not know if you can use CO2 for bottling but sugar will not carbonate.

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