SG of carbonated beer?

OK, so I was in a hurry. I made an Amber a few weeks ago, OG = 1.066. Fermentables were 12.5# 2-row, .5# 90L, .5# 120L. The mash was a full 60 minutes at 153 deg. Yeast was S04, and fermentation temp was 65. I did not take a final gravity reading after the primary or after the secondary. I kegged and force carbonated yesterday, and the beer is sweet with some diacetyl. This is similar grain bill to other beers I have brewed, but I have not used S04 before. After countless batches, I guess I have started to cut some corners. I am curious to figure out what went wrong. My question is how much will carbonation throw off a gravity reading? Can I just fill up the sample tube from the keg and warm it up, or do I need to let it sit for a day to let it go flat?

Thanks!

Stir it with a fork. Poof! No more carbonation.

Let it go flat. My thoughts are that the CO2 that's dissolved into the beer will create little air pockets that will throw off your hydrometer. I wouldn't worry too much about it. If you used a secondary on a 1.066 beer, then it's probably done...unless you rushed it right out of primary after a week and only used secondary for another week.

As you've said...you're cutting corners. This is a bad habit to get into and is more than likely why your beer has a diacetyl taste to it. How much did your temps fluxuate?

I've used S-04 twice for the same recipe. 1st time it came out sweet and slightly fruity I thought it was me, second time I decided I won't use it again. Wasn't bad, just wasn't for me.

Suthrncomfrt1884 said:

As you've said...you're cutting corners. This is a bad habit to get into and is more than likely why your beer has a diacetyl taste to it. How much did your temps fluxuate?

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Point taken. My last house had wildly fluctuating temps in the basement, so I am pretty anal about controlling the temps. I am currently sampling one from the tap. It was still a bit flat after force carbonating, so I let it sit for a day at 25 psi. I am assuming that it also got a bit colder after a second day in the fridge. The diacetyl taste is gone, and the sweetness is down quite a bit. I warmed up a sample in the hydrometer tube and bounced the hydrometer up and down quite a few times to knock out the carbonation. It is sitting at 1.014. I will leave it overnight to see what happens. I am wondering if the warmer than usual temp, low carbonation, S04, and the 120L was enough to throw my taste buds off? There is still a slight, almost raisinlike, fruitiness to it. Maybe, again, from the 120L and S04? I am not sure, as I don't normally use either one. It is starting to grow on me, and I will definitely open it up for public consumption.