Author Topic: Proper sample temp for reading OG and FG  (Read 601 times)

Offline Bevilaquafoto

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Proper sample temp for reading OG and FG
« on: January 28, 2016, 02:50:42 PM »
I have been reading about hydrometer calibration, and I tested mine. The side of my hydrometer says that it's most accurate when the sample is 60 degrees. In every recipe you are given a target start and end gravity, but they never mention at what temperature? Should I always chill my samples to 60 degrees, or just use an alcohol calculator to factor in the few degrees of temperature difference? When doing small all-grain batches, one should take a reading after mashing to check efficiency, and see how much sugar has been extracted. Does this mean that I have to take a sample, wait to proceed until it's chilled and then read it and continue to my boil? Forgive the beginner question, but I could use the proper information.
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Offline jrcrilly

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Re: Proper sample temp for reading OG and FG
« Reply #1 on: January 28, 2016, 03:32:18 PM »
Taking samples during the mash is where a refractometer shines. It gives you the information immediately, when you need it rather than after a prolonged cooling period. That way you know what to do now, rather than what you should have done 1/2 an hour ago.

Or you can use this (or any similar) calculator to correct for the difference between a sample's temperature and 60 degrees.   http://hbd.org/cgi-bin/recipator/recipator/hydrometer.html

As you can see, the difference at room temperature will be very small and can pretty much be ignored. It is when the liquid is hot (such as mash temperatures) that the error is significant.

Offline HoosierBrew

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Re: Proper sample temp for reading OG and FG
« Reply #2 on: January 28, 2016, 03:51:06 PM »
I have been reading about hydrometer calibration, and I tested mine. The side of my hydrometer says that it's most accurate when the sample is 60 degrees. In every recipe you are given a target start and end gravity, but they never mention at what temperature? Should I always chill my samples to 60 degrees, or just use an alcohol calculator to factor in the few degrees of temperature difference? When doing small all-grain batches, one should take a reading after mashing to check efficiency, and see how much sugar has been extracted. Does this mean that I have to take a sample, wait to proceed until it's chilled and then read it and continue to my boil? Forgive the beginner question, but I could use the proper information.


Don't bother with chilling your sample to 60F. Calculators like the one at Brewer's Friend are plenty accurate enough to correct for temp.


Edit - Here's the link:   http://www.brewersfriend.com/hydrometer-temp/
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Re: Proper sample temp for reading OG and FG
« Reply #3 on: January 28, 2016, 04:45:00 PM »
I have been reading about hydrometer calibration, and I tested mine. The side of my hydrometer says that it's most accurate when the sample is 60 degrees. In every recipe you are given a target start and end gravity, but they never mention at what temperature? Should I always chill my samples to 60 degrees, or just use an alcohol calculator to factor in the few degrees of temperature difference? When doing small all-grain batches, one should take a reading after mashing to check efficiency, and see how much sugar has been extracted. Does this mean that I have to take a sample, wait to proceed until it's chilled and then read it and continue to my boil? Forgive the beginner question, but I could use the proper information.


Don't bother with chilling your sample to 60F. Calculators like the one at Brewer's Friend are plenty accurate enough to correct for temp.


Edit - Here's the link:   http://www.brewersfriend.com/hydrometer-temp/

Although those get more inaccurate the further you are from 60.  I've given up on refractometers...I've never been able to get accurate readings.  Now I take 8 oz. of wort and put it in a metal cocktail shaker.  I swirl that in a bowl of ice water an in about 45-60 sec. it's gone from boiling to 60 so I can get a reading with my hydro
meter.
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Offline HoosierBrew

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Re: Proper sample temp for reading OG and FG
« Reply #4 on: January 28, 2016, 04:53:38 PM »
I have been reading about hydrometer calibration, and I tested mine. The side of my hydrometer says that it's most accurate when the sample is 60 degrees. In every recipe you are given a target start and end gravity, but they never mention at what temperature? Should I always chill my samples to 60 degrees, or just use an alcohol calculator to factor in the few degrees of temperature difference? When doing small all-grain batches, one should take a reading after mashing to check efficiency, and see how much sugar has been extracted. Does this mean that I have to take a sample, wait to proceed until it's chilled and then read it and continue to my boil? Forgive the beginner question, but I could use the proper information.


Don't bother with chilling your sample to 60F. Calculators like the one at Brewer's Friend are plenty accurate enough to correct for temp.


Edit - Here's the link:   http://www.brewersfriend.com/hydrometer-temp/

Although those get more inaccurate the further you are from 60.  I've given up on refractometers...I've never been able to get accurate readings.  Now I take 8 oz. of wort and put it in a metal cocktail shaker.  I swirl that in a bowl of ice water an in about 45-60 sec. it's gone from boiling to 60 so I can get a reading with my hydro
meter.


You're right, Denny. I should've mentioned I use use hydrometers just for FG, where the temp differential isn't a lot. I use refractometers for preboil and postboil OG.
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Re: Proper sample temp for reading OG and FG
« Reply #5 on: January 28, 2016, 04:55:03 PM »
You're right, Denny. I should've mentioned I use use hydrometers just for FG, where the temp differential isn't a lot. I use refractometers for preboil and postboil OG.

I have 3 refractometers and not one agrees with my hydrometer no matter how I calibrate them.  Rather than buy a 4th, I just changed my method and I'm perfectly happy with it.
Life begins at 60.....1.060, that is!

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Offline HoosierBrew

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Re: Proper sample temp for reading OG and FG
« Reply #6 on: January 28, 2016, 04:59:19 PM »
You're right, Denny. I should've mentioned I use use hydrometers just for FG, where the temp differential isn't a lot. I use refractometers for preboil and postboil OG.

I have 3 refractometers and not one agrees with my hydrometer no matter how I calibrate them.  Rather than buy a 4th, I just changed my method and I'm perfectly happy with it.


 I must've gotten lucky. Mine reads pretty consistently close to my hydros. Close enough that I like being able to use it preboil anyway. I still like a hydro for FG though.
Jon H.

Offline Bevilaquafoto

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Re: Proper sample temp for reading OG and FG
« Reply #7 on: January 28, 2016, 06:13:18 PM »
Thank you all! Great information all around. Much appreciated.
Lorenzo Bevilaqua
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