After 17 days in the fermenter (much longer than I normally leave it), I’ve transferred my latest imperial stout into a keg.

In order to try and nail whether my ‘too much yeast in sample’ theory on preciously misses final gravity targets was correct, I took samples at start, ~25%, ~50% and ~75% of the way through the transfer for refractometer measures and an additional hydrometer sample at ~75%.

Somewhat frustratingly the refractometer result was the same for all 4 samples and around the same high level of previous brews (around 1.042 specific gravity)..

.. however the hydrometer returnes 1.022 a mere 0.006 above my final target!

One of these devices requires tuning (by a clueless me) and the other is likely accurate!

So the estimated ABV on the brewsheet is 8.9% (though the brewer’s friend calculator corrects that to 8.8%) and I have hit 8.01%!

I shall celebrate in a few weeks once it has carbonated!

shot of hydrometer resting at 1.02SG in a beaker of imperial stout


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Comments & Replies

Ruaraidh replied to this post here

@jk good progress there, what's your hydrometer like?

Any further views on what's causing the data being off?

J K 🇯🇵🏴󠁧󠁢󠁳󠁣󠁴󠁿 replied to this post here

This was just the lift I needed after a tough few days of trying to get my head around microbial metabolism!

J K 🇯🇵🏴󠁧󠁢󠁳󠁣󠁴󠁿 replied to this post here

@athairbirb it's a sealed glass apparatus with ball bearings, wax(?) and floats to measure the density of sugar, the more sugar the higher it floats.

The refractometer requires manual tuning and it could be that I've not done that well, maybe the water when doing so was way too cold or something. So of the two, much less likely to be accurate.

It makes sense as my beer a few brews ago kicked like a mule, but according to my measurements merely breaches 4%.. I suspect that if I'd used the hydrometer it would have told a different story!

J K 🇯🇵🏴󠁧󠁢󠁳󠁣󠁴󠁿 replied to this post here

Errr preciously misses = previously missed

J K 🇯🇵🏴󠁧󠁢󠁳󠁣󠁴󠁿 replied to this post here

I calibrated it with water, but I suspect it was too cold. So I am pleased to see you mention temperature sensitivity!

Calculations? Just reading the specific gravity, then entering the Original and Final gravity figures into the Brewer's Friend website calculator. Still very much a novice in this respect.

I tuned it to the same measurement as the hydrometer with the correct temperature wort so will see if it is even close to the original gravity next time I brew!