Measuring FG after bottling

[gkeusch]

I suppose this is a dumb question but here goes:
I bottled my batch of beer, forgetting to measure my Finished Gravity. If I check it now on a carbonated sample from a bottle, should I get the same reading I would have gotten had I taken it before adding the priming sugar? (assuming the temperature is a constant.)

The good news is that now I can drink the sample.

 

[zoebisch01]

No you'll get a higher gravity reading. You have to back calculate what the amount of sugar contributed in terms of gravity, assuming that it has been less than a day. Otherwise the yeast will have already changed the reading yet again.

Oh wait I misread. Yeah you should get a very close one to what you'd have prior to bottling, that is assuming your priming sugar has been all used up. But that's a bassackwards way of doing it. Not sure if I am missing anything there though. I'd just skip it and not worry

 

[DeathBrewer]

don't concern yourself, you only use that small amount of sugar to carbonate the beer and it will be a VERY small difference from what your FG was before bottling

 

[david_42]

You will get a slightly lower reading IF you primed with corn sugar or something else that is 100% fermentable, because the ABV went up slightly and alcohol is lighter than water or sugar.

Very slightly lower. Very.

 

[Joker]

Wouldn't the bubbles throw off the readings?

In addition if you never checked FG your lucky you didn't get bottle bombs, unless you just let it sit for a long time prior to bottling then your safe.

 

[TexLaw]

Wouldn't the bubbles throw off the readings?

In addition if you never checked FG your lucky you didn't get bottle bombs, unless you just let it sit for a long time prior to bottling then your safe.

Yes, bubbles will throw off your reading, but you can usually get a good reading by gently spinning or tapping your hydrometer. A few bubbles on there or some very small bubbles won't throw your reading off by enough to matter, just like priming sugar wouldn't.

Just FYI, adding the typical 5 oz. of dextrose to a five gallon batch raises SG by about 0.002.


TL

 

[Bobby_M]

let it go flat in the tube first.