Author Topic: Finishing gravity results  (Read 988 times)

Offline troybinso

  • Assistant Brewer
  • ***
  • Posts: 219
    • View Profile
Finishing gravity results
« on: February 26, 2013, 02:33:28 PM »
I split a batch of 1.056 pale ale into four different carboys, and pitched four different yeasts. The four yeasts are WY1056, WY1318, WY1968, and WLP007. The beer has fermented for about 10 days and is done now. I thought I would take hydrometer samples of all of them a record the results, and I also wanted to test the refractometer reading against the hydrometer.

First beer: Yeast: WY1056
First hydrometer reading: 1.013, refractometer reading (adjusted in BeerSmith): 1.016
then I waited a couple of hours and took the readings again with the same sample
Second hydrometer reading: 1.011, refractometer reading: 1.010

Second beer: Yeast: WY1318
First hydrometer reading: 1.016, refractometer reading: 1.018
waited a couple of hours
Second hydrometer reading: 1.015, refractometer reading: 1.013

Third beer: Yeast: WY1968
First hydrometer reading: 1.017, refractometer reading: 1.020
waited a couple of hours
Second hydrometer reading: 1.015, refractometer reading: 1.020

Fourth beer: Yeast: WLP007
First hydrometer reading: 1.014, refractometer reading: 1.016
waited a couple of hours
Second hydrometer reading: 1.013, refractometer reading: 1.015
« Last Edit: February 26, 2013, 05:03:19 PM by troybinso »

Offline morticaixavier

  • Official Poobah of No Life.
  • *
  • Posts: 6074
  • Davis, CA
    • View Profile
    • The Best Artist in the WORLD!!!!!
Re: Finishing gravity results
« Reply #1 on: February 26, 2013, 02:35:45 PM »
did you account for temperature changes?
"Creativity is the residue of wasted time" - A. Einstein

Jonathan I Fuller

Offline troybinso

  • Assistant Brewer
  • ***
  • Posts: 219
    • View Profile
Re: Finishing gravity results
« Reply #2 on: February 26, 2013, 02:36:37 PM »
Anyway, not sure what to make of most of this information, but I thought I would just put it out there as some data points. The one thing that sticks out is that the refractometer just isn't very accurate on fermented beer. Also, I think the co2 in solution might make the first hydrometer readings a little higher.

Offline troybinso

  • Assistant Brewer
  • ***
  • Posts: 219
    • View Profile
Re: Finishing gravity results
« Reply #3 on: February 26, 2013, 02:38:11 PM »
Temperature at the first reading was 69 degrees, and the temperature at the second reading was 63. I adjusted the first hydrometer reading to account for the temperature by adding .001 points.
« Last Edit: February 26, 2013, 03:37:08 PM by troybinso »

Offline a10t2

  • Official Poobah of No Life.
  • *
  • Posts: 3207
  • Ask me why I don't like Chico!
    • View Profile
    • SeanTerrill.com
Re: Finishing gravity results
« Reply #4 on: February 26, 2013, 02:44:08 PM »
The one thing that sticks out is that the refractometer just isn't very accurate on fermented beer.

I was actually surprised you got so close given that you're using BeerSmith.
Beer is like porn. You can buy it, but it's more fun to make your own.
http://seanterrill.com/category/brewing/

Offline troybinso

  • Assistant Brewer
  • ***
  • Posts: 219
    • View Profile
Re: Finishing gravity results
« Reply #5 on: February 26, 2013, 02:53:57 PM »
The one thing that sticks out is that the refractometer just isn't very accurate on fermented beer.

I was actually surprised you got so close given that you're using BeerSmith.

Is there a more accurate calculator?

Offline a10t2

  • Official Poobah of No Life.
  • *
  • Posts: 3207
  • Ask me why I don't like Chico!
    • View Profile
    • SeanTerrill.com
Re: Finishing gravity results
« Reply #6 on: February 26, 2013, 03:04:54 PM »
Is there a more accurate calculator?

Well, since you asked... ;)

http://seanterrill.com/refractometer should be within 0.002 about 90% of the time, statistically speaking.
Beer is like porn. You can buy it, but it's more fun to make your own.
http://seanterrill.com/category/brewing/

Offline reverseapachemaster

  • Senior Brewmaster
  • ******
  • Posts: 1041
    • View Profile
    • Brain Sparging on Brewing
Re: Finishing gravity results
« Reply #7 on: February 26, 2013, 03:18:38 PM »
I also wonder whether any of those results are adjusted for temperature.

I just recently obtained a refractometer. It's definitely not a perfect way to assess FG but it's close enough for my needs. Since I brew a lot of small batches it's painful to lose beer to the test tube but no big deal to lose a few drops. So it's very advantageous to me. I'm happy with it even if I have to run to the computer to plug in the data into a calculator to understand what I'm seeing.
Heck yeah I blog about homebrewing: Brain Sparging on Brewing but I'm also a lawyer: The Kielich Law Firm

Offline dordway29

  • Cellarman
  • **
  • Posts: 47
    • View Profile
Re: Finishing gravity results
« Reply #8 on: February 26, 2013, 03:28:15 PM »
Alcohol will cause the refractometer to read higher than it should. Even with the calculators I prefer the hydrometer for TG readings. That way you can taste the results as well.

Offline troybinso

  • Assistant Brewer
  • ***
  • Posts: 219
    • View Profile
Re: Finishing gravity results
« Reply #9 on: February 26, 2013, 05:02:56 PM »
Updated the original post with the other two beers.

a10t2: your refractomter page does seem to be a little more accurate than the beersmith calculator. Thanks for the link.

I think another factor to consider in some of these differences is my error in reading the hydrometer and refractometer. Especially the refractometer. It is pretty tough to get an exact number to the .1 spot with those lines so close together.