[jeeyeop]

just finished brewing a scotch ale and I had a question about concerning the gravity readings

pre-boil I had 4.5 gallons of wort at 1.052 SG. My hydrometer's calibrated for 60F and the wort was 150F. After adjusting for temperature I found my pre-boil SG to be at 1.070.

post-boil I had a reading for 1.084 at 3.25 gallons of wort. After adjusting the reading for a 70F wort, my SG is 1.085.

however, shouldn't it be at ~1.097. If I take the 4.5 gallons multiplied by the 70 SG and divide by the new volume of 3.25, that's what I should be getting right? I lost a little bit of volume by whatever was absorbed by the hop bag (1.5 oz worth of fuggles), but it doesn't seem like enough to account for a .012 difference in gravity.

am i calculating something wrong, or is this relatively normal?

thanks guys! im posting way too much nowadays cause the answers are always good and quick : /

[PORTERHAUS]

I personally do not know a way of what you are trying to calculate. But my calculator in my brewing software matches what you gave for your readings at those temps. As far as the 3.25 gals, was that the volume in the kettle after the boil or is that what you had into the fermenter? How long was your boil?

[a10t2]

You'll never get an accurate hydrometer reading at 150°F, IME. That's where a refractometer is your best bet.

[HoosierBrew]

You'll never get an accurate hydrometer reading at 150°F, IME. That's where a refractometer is your best bet.

+1.  Refractometer rocks for preboil OG.

[jeeyeop]

oh great, more goodies to add to the arsenal!

im using a 5 gallon stainless steel pot so it's kind of hard for me to know the volume unless it's filled to the brim. i just know the 3.25 since there are markings on my fermenting bucket, but everything from the kettle went into the bucket minus the 1.5 oz of hops in a hop bag and whatever it absorbed. my strainer picked up very minimal residue

i think i saw the formula somewhere in "how to brew"

looking forward to this beer although I don't know how scotch it will taste, it's way darker than I thought it'd be

[RPIScotty]

Sounds like you mis measured something. Correcting for hydrometer readings at high temps is bound to give you an issue as Sean stated. Also without accurate volume measurements your bound to have errors in calculating gravities.


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