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Hydrometer vs. Refractometer Reading

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oasisbliss

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I just got done doing a bavarian hefe (thanks Ed Wort!)
here is what I got on my gravity readings...after chilling wort post boil.
I pulled a sample for my hydrometer and it was cooled to about 70f I got 1.052
then I took the same sample on my refractometer (that was calibrated with distilled water) that was 1.060
Can anyone explain this big difference?

Thanks for input
 

RmikeVT

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have you calibrated your hydrometer in 60* distilled water? I know my hydrometer reads about 4 points too low.
 

Bobby_M

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Right, most hydrometers are calibrated to 59F. The other thing to check is the scale of your refractometer. What brix number lines up with that 1.060?
 

Intimnasc

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I wanted to look at refractometers at my Local Brew Store and the guy told me it was a waste for extract brewing that the hydrometer would be way more accurate. Is this correct?
 

bmac

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Intimnasc said:
I wanted to look at refractometers at my Local Brew Store and the guy told me it was a waste for extract brewing that the hydrometer would be way more accurate. Is this correct?
Refractometers are great at taking quick readings while all grain brewing. I use mine to check my run off gravity near the end of sparging, to take pre boil gravity, mid boil gravity just to make sure i'm where i thought i would be and post boil to get my starting gravity numbers. With an atc refractometer you don't need to cool the wort and you only need a couple of drops of wort to get an accurate reading. After fermentation is complete you will need to make adjustments to the reading you get from a refractometer due to alcohol being present, but there are calculators online or in beersmith that will make that a piece of cake.
 

johnp

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Intimnasc said:
I wanted to look at refractometers at my Local Brew Store and the guy told me it was a waste for extract brewing that the hydrometer would be way more accurate. Is this correct?
It's not that they are more accurate. You don't need to check starting gravity with extract because you know exactly how much sugar you have in the beer.

Plus you can't use a refrac to determine FG, due to the presence of alcohol, though there are converters available online.

So I'd say he was correct that refractometers are less practical for extract, but not because they are any less accurate.
 
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oasisbliss

oasisbliss

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I am doing AG - my biggest question is why the big difference? from 1.060 to 1.052 ?
 

librewer

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have you calibrated your hydrometer in 60* distilled water? I know my hydrometer reads about 4 points too low.
This... grab a jug of distilled water and check it. If you have an adjustment screw, adjust your refractometer. As far as the hydrometer, if it was calibrated at 59 (should see this stamped/printed somewhere on it) then your reading at 70 would be about 1 point off.... resulting in a corrected 1.053 SG.
 

Bobby_M

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I can't figure out that wide of a discrepancy but librewer does show that the actual temp adjusted SG was probably 1.053.

The issue with the refractometer can be related to the calibration and actual handling. First, if you calibrated it inside the house at 68F room temp and then used it outside in 34F, you have a calibration issue. Try recalibrating when the instrument is temp conditioned to where you'll be measuring. The second issue that can result in an inflated gravity reading on a refractometer is evaporative concentration. If you take 1/2mL of sample wort and drop it on the prism where it flattens out to a paper thin layer, you can easily evaporate out 1/10th of the volume and therefore concentrate the sugar content. I always take my pipet with sample and invert it into a small cup of icewater just to knock the sample temp down closer to ambient temps to avoid this issue. Also, getting the cover down on the sample very quickly helps.
 

stpug

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In line with what bobby_m states about evaporative concentrations, I have noticed that if you are reusing the same spoon/tool for your samples then you need to make sure and rinse/dry it between uses because during the time between samples the wort can evaporate its liquid component leaving a high-sugar concentration dry layer on the spoon. If this same spoon/tool is quickly dipped for another sample then that high-sugar layer goes back into solution to create a higher-than-actual wort sugar concentration leading to increased refractometer readings.
 

Quattlebaumpt

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Well i have noticed that any and i mean any particles like hops or grain pieces are in that little drop it throws off the entire reading. It's to much of a pain in the ass to use because of that. But maybe i am doing something wrong? i just pull a little and chilled to desired temp and take a hydro reading. Works every time. refractometer was a waste of $$ for me:(
 

Bobby_M

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Well, it depends on how you look at refractometer use. I use it during fly sparging to make sure I'm not oversparging. There's no way in hell I'm going to keep collecting 3 ounces and putting it in an ice bath for 5 minutes a bunch of times during the sparge. Even if the instrument is giving me slightly skewed readings at this stage, I'm looking for approximately 3 brix or 1.010 to know when to stop. I don't care if it's 3.4 brix or 1.008 actual.
 

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