refractometer help needed

Discussion in 'Beginners Brewing Forum' started by Fat Duck Brewery, Apr 23, 2018.

  1. Fat Duck Brewery

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    Hi all

    Well I've invested into buying a refractometer to try and improve my gravity reading skills, but im a little confused.

    Now is the refractometer only to be used for reading your OG (original gravity) prior to yeasting? or can it also be used to check your final gravity?

    I ask, as when i use my refractometer and hydrometer at the OG stage I get very close readings, but when I do it again at the FG stage the readings are miles apart.
    I've now tried this on a few beers and its always a big difference and i mean the hydrometer reads 1012 and the refractometer reads 1038.

    Now I've calibrated the refractometer and would include a temp difference for my hydrometer, so I just don't understand why I get such a difference?

    The only thing i can now think is that the refractometer shouldn't be used to read the FG, which I would find strange as its no different really than reading the OG.

    Any clues or tips welcomed

    Cheers all
     
  2. Hawkbox

    Hawkbox Well-Known Member

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    Refractometers don't do alcohol well by default. It screws up the light refraction. I use a hydrometer for the FG as I'm to lazy to do the math on a refractometer reading.
     
  3. Ozarks Mountain Brew

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    I only use a refactor with wort not finished beer, there are correction formulas on this site though I haven't tested them, just do a search for refactor
     
  4. Mase

    Mase Well-Known Member

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    I use the calculator on this site with my Refractometer and have double checked against hydrometer reading and they're pretty darn close.
     
  5. Ozarks Mountain Brew

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  6. Fat Duck Brewery

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    Thanks, so I'm not so stupid then ;-)
     
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  7. Nosybear

    Nosybear Well-Known Member

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    You can use it after fermentation starts but you have to correct the reading. I use a spreadsheet to correct for alcohol, the calculator on this site works well.
     
  8. Aje1967

    Aje1967 New Member

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    Does anyone have any tips for downloading the calculator for a Mac computer. I can't open it. :(

    My wife got me a refractometer for xmas, but I have not used it yet.
     
  9. thunderwagn

    thunderwagn Well-Known Member

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    AFAIK it's use online only. I think all calcs on BF are cloud based.
     
  10. dmtaylor

    dmtaylor New Member

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    #10 dmtaylor, Jan 27, 2019
    Last edited: Jan 27, 2019
    If you can open a spreadsheet program similar to Excel, then you can use the following equations to calculate the OG and FG, respectively, where C8 is the initial Brix reading, D8 is the final Brix reading, and $E$3 is the wort correction factor (mine = 0.99 for my refractometer, yours might be anything from 0.95 to 1.05).

    =(C8/$E$3)/(258.6-(((C8/$E$3)/258.2)*227.1))+1

    =0.00001335 * C8/$E$3 * C8/$E$3 - 0.00003239 * C8/$E$3 * D8/$E$3 + 0.00002916 * D8/$E$3 * D8/$E$3 - 0.002421 * C8/$E$3 + 0.006219 * D8/$E$3 + 1

    As far as I can tell, these are the same Petr Novotny formulae used by BrewersFriend.com.

    For MUCH more information including great tips from yours truly at top of page 2, see the following link:

    https://www.homebrewersassociation.org/forum/index.php?topic=28544.0
     
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  11. Hawkbox

    Hawkbox Well-Known Member

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    That's my understanding too. Just take the Mac with you when you brew.

    I love my refractometer.
     
  12. Mase

    Mase Well-Known Member

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    I brew in my garage that is detached from the house and we have poor wi-fi as it’s too far away. Since I use the infusion calculator, is simply open the calculator and leave it on open on my phone, so when I’m ready to heat the HLT, I can plug in all my info then. I’m sure the refractometer tool would work the same.
     
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  13. Hatseflats

    Hatseflats New Member

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    I´m using Linux Mint and it works properly. There´s no need to install any software.
     
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