Reading spec gravity at high temps

[_JP_]

Brew day yesterday:

11.5 lb 2-row
1.5 lb 120L crystal

Hit my mash temp of 154°F perfectly. Stirred, came back, stirred, checked again. Still 154°.

Fly sparged and got 6.1 gal of 1.032 @ 144°F (equivalent to 1.049 @ 60°).

Boil 60 min, got 5.0 gal of 1.078 @ 87°F (equivalent to 1.082 @ 60°F).


Does this sound right? 1.049 pre-boil sounded real low to me. I didn't check my efficiency yet.

 

[JasonInBTR]

Did you use a hydrometer to measure you SG? They are wildly inaccurate over 100F. When I used a hydrometer I would take a pitcher and fill it up with ice water, fill my sample tube using a turkey baster and stick it in the ice water bath for a bit to get it down below 80F.

I do believe AHS now sells a hydrometer that is corrected at around 150F to take mash temp readings.

I now have a refractometer and brewday SG reading are soooo much easier.

Jason

 

[archiefl98]

Well, as you say you started with 6.1 gallons at 1.049 you would have had to boil off 2.52 gallons leaving 3.44 gallons final volume to hit a gravity of 1.087 (all according to BeerSmith, assuming I'm using the boiloff tool correctly)

I would say it's more likely that the hydrometer correction is an approximate. I've had the same issue. Instead try this:

1. Run off sparge to the boil kettle
2. Stir up everything in the boil kettle real well
3. Pull about a half cup of the wort from the boil kettle
4. Put the container with the wort in the freezer for about 10-15 minutes
5. Once it gets to about 60 degrees take your preboil gravity reading

My freezer usually chills my sample down to 60F just a few minutes before my 11.5 gallons starts to boil.

 

[_JP_]

Yes, I took readings with a hydrometer. It seemed like something was off there.....

Using my 1.078 @ 87°, 5.0 gal, could someone run beersmith for me and compute my efficiency? (Pleeeese?)

Calculation by hand, assuming 1.1 gal water at 1.000 sg evaporated, yields an O.G. of 1.067 at 60°, which sounds about right. That gives me 86% efficiency though. Did I do that good of a job?

 

[_JP_]

Well, as you say you started with 6.1 gallons at 1.049 you would have had to boil off 2.52 gallons leaving 3.44 gallons final volume to hit a gravity of 1.087 (all according to BeerSmith, assuming I'm using the boiloff tool correctly)

I would say it's more likely that the hydrometer correction is an approximate. I've had the same issue. Instead try this:

1. Run off sparge to the boil kettle
2. Stir up everything in the boil kettle real well
3. Pull about a half cup of the wort from the boil kettle
4. Put the container with the wort in the freezer for about 10-15 minutes
5. Once it gets to about 60 degrees take your preboil gravity reading

My freezer usually chills my sample down to 60F just a few minutes before my 11.5 gallons starts to boil.

Thanks for the tip. I'll do that next time.


I've been thinking of getting a refractometer, but they're no good post-fermentation because of the alcohol content, right? So I'd still need the hydrometer.....

 

[archiefl98]

Sorry, dyslexia is kicking in early this morning.

5 Gallons 1.078 OG @ 87F = 5 Gallons 1.082 OG @ 60F

Preboil would have been 6.1 Gallons (as you said) of 1.067 @ 60F

With these numbers I get:
Brewhouse Efficiency 87.68%
Boiler Efficiency 85.97%
Fermenter Efficiency 87.68%


As for refractometers, they work great pre-fermentation, and you can use a correction algorithm for post-fermentation.
http://brewhardware.com/index.php?option=com_content&view=article&id=77&Itemid=72

 

[_JP_]

Sorry, dyslexia is kicking in early this morning.

5 Gallons 1.078 OG @ 87F = 5 Gallons 1.082 OG @ 60F

Preboil would have been 6.1 Gallons (as you said) of 1.067 @ 60F

With these numbers I get:
Brewhouse Efficiency 87.68%
Boiler Efficiency 85.97%
Fermenter Efficiency 87.68%


As for refractometers, they work great pre-fermentation, and you can use a correction algorithm for post-fermentation.
http://brewhardware.com/index.php?option=com_content&view=article&id=77&Itemid=72

Thanks for the calculation!