Gravity gone up - now bottled at 1028

[kodak79]

Evening all. I have just bottled a Russian Imperial Stout and after bottling checked my gravity reading to find that it at 1028.
The brew started at 1080 and after 3 days was down to 1026. After 7 days it was 1020 and I added 2 bags of hop pellets and left for another 4 days before cold crashing to 2C for 2 days (but annoyingly forgot to take a gravity reading at this point).
Then tonight I got around to bottling and after racking to a 2nd vessel, adding 150g of priming sugar and bottling I took a gravity reading and found that it is now at 1028. The temperature was a bit lower at around 9C by then but that would only make about 1 point difference.
Does anyone have any thoughts or experience on this as I'm now a bit bothered as they are in bottles (decided an 8% stout would be a bit much on tap from the Corny kegs) and I'm worried about bottle bombs.
Thanks,
Chris

 

[Zephyr259]

The way you wrote that makes it sound like you took the gravity reading after adding the priming sugar which would increase the FG, but not normally by 8 points. How do you get your samples? It's possible the beer had stratified a bit?

Also, just my curiosity, but what are you brewing? Dry hopping an RIS is a bit unusual.

 

[foxy]

Two things to consider, hop creep, and taking a gravity after adding priming sugar don't under estimate the ability of yeast to work at low temperatures. How long after adding priming sugar did you take a reading?

 

[kodak79]

After I transferred the beer into a 2nd vessel I added the sugar. I then cleaned the fermenting vessel and transferred it back so I could use the tap on the bottom with my bottling wand. Then I sterilised the bottles, so by the time I took the sample it may have been 30 minutes to an hour from adding it.
A friend suggested that co2 could have getting released from suspension as the beer warmed and that would have had the effect of showing the reading higher so I left it overnight and now it shows 1026.
How much could 150g of sugar affect the gravity of a 21 litre brew?

 

[kodak79]

The way you wrote that makes it sound like you took the gravity reading after adding the priming sugar which would increase the FG, but not normally by 8 points. How do you get your samples? It's possible the beer had stratified a bit?

Also, just my curiosity, but what are you brewing? Dry hopping an RIS is a bit unusual.

It was 150g of Columbus pellets. It's a (very expensive) kit that I'd been toying with for ages and finally decided to spent the money. This one Russian Imperial Stout - Beerworks Craft Brewery Series Beer Kit - Love Brewing
Took the sample from the bottling wand while bottling the beer had been pretty mixed up by then.

 

[terrym]

@kodak79
Sounds like you were in a rush to get this complex high gravity beer into bottles. From pitching to bottling only took 13 days, including a crash cool period. I often leave normal gravity beers for longer.
Next 150g of table sugar will add about 3 gravity points. The temperature correction for your hydrometer if calibrated at 20*C and measuring at 9*C is -1 point as you say.
So there appears to be a discrepancy of about 4 gravity points, which in my view can't really be accounted for other than by reading error.
However given you may have rushed things there is a small chance the primary may not have finished and so there may still be unfermented sugars left in the beer in addition to the priming sugar. That said assuming the OG and first FG readings were correct you achieved 74% which is respectable, but that's without knowing more about the wort make up and yeast used
Therefore it appears you have two main choices. Leave it as it is and chance it. Or doing something about it. The 'do something about it' option could consist of carefully emptying, without splashing, all your bottles back into the FV and leaving it at fermenting temperature for another two weeks or so for the fermentable sugars to get consumed, and then repackage when you are satisfied it has finished There will be enough sugar in there to purge out the headspace with CO2. Others may have better ideas.

 

[kodak79]

@kodak79
Sounds like you were in a rush to get this complex high gravity beer into bottles. From pitching to bottling only took 13 days, including a crash cool period. I often leave normal gravity beers for longer.
Next 150g of table sugar will add about 3 gravity points. The temperature correction for your hydrometer if calibrated at 20*C and measuring at 9*C is -1 point as you say.
So there appears to be a discrepancy of about 4 gravity points, which in my view can't really be accounted for other than by reading error.
However given you may have rushed things there is a small chance the primary may not have finished and so there may still be unfermented sugars left in the beer in addition to the priming sugar. That said assuming the OG and first FG readings were correct you achieved 74% which is respectable, but that's without knowing more about the wort make up and yeast used
Therefore it appears you have two main choices. Leave it as it is and chance it. Or doing something about it. The 'do something about it' option could consist of carefully emptying, without splashing, all your bottles back into the FV and leaving it at fermenting temperature for another two weeks or so for the fermentable sugars to get consumed, and then repackage when you are satisfied it has finished There will be enough sugar in there to purge out the headspace with CO2. Others may have better ideas.

Thanks for your thoughts, very helpful. Given the reading taken after leaving the sample overnight had dropped to 1026, then if the sugar adds 3 points then I just have a random 3 unaccounted.
Target was 1018 so was pretty close before the hops went in.
I'm think I'll just release any gas in there and reseal tonight. There's 43 in grolsch bottles and 4 in crown capped 330ml bottles so I'll pop a crown cap after a week and see how it is.
Can hop addition increased gravity?