Author Topic: Refractometer Calibration  (Read 3092 times)

Offline Ushman92

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Refractometer Calibration
« on: February 15, 2019, 01:28:39 PM »
Hello,

So I bought a Refractometer so I can constantly monitor my pre-boil gravity so I can control my post boil gravity more effectively. Though I had a brew day last week and I constantly measured my gravity with the refractometer giving me entirely different results every time.

pre-boil 1.048ish
added dme
1.040ish!?!?!
added dme
1.035ish?!?!?!?!?!?!
Then I just gave up.

My post OG turned out to be 1.040

I had no idea what was going on, but I missed my target (by alot) because I could not rely on my readings.

All i did to calibrate it, was I took the water I was brewing with, and I made sure it was on 1.000 on the refractometer.

What more should I do to ensure I am getting accurate readings?

My purchase:
https://www.amazon.com/gp/product/B00AOCKWMU/ref=ppx_yo_dt_b_asin_title_o02__o00_s00?ie=UTF8&psc=1

Offline Kevin58

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Re: Refractometer Calibration
« Reply #1 on: February 15, 2019, 02:45:46 PM »
Your new refractometer should have come with an instruction sheet. To calibrate you should use distilled or RO water. Place a drop on the glass, close the cover and holding the refractometer level sight through the eyepiece. If the reading you get is not already at 0 Brix turn the adjusting screw until it does.

One common cause of inconsistent readings is not stirring your mash well and not cooling your sample to the same temp for each reading.

I personally like to use a calibrated hydrometer side by side with my refractometer too.
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Offline dtapke

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Re: Refractometer Calibration
« Reply #2 on: February 15, 2019, 02:57:05 PM »
I use the same brand refrac, works great.

Perhaps provide us with the brix reading and not the "corrected" reading.

12.25 brix should be around 1.048

from there with addition of DME and proper stirring of the boil kettle you should get obviously higher readings.

if you measured 12.25 brix of your wort, then sparged into the kettle, you would end up with a lower reading as you're adding water, diluting the sample.


Could you elaborate on your recipe, when/where you took readings, and the brix readings?

a .BSMX file of the recipe makes this a lot easier, as it allows others to plug the recipe into their BS and look to see where issues could've happened.
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Offline Oginme

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Re: Refractometer Calibration
« Reply #3 on: February 15, 2019, 05:34:52 PM »
Another common issue with refractometers is that residual sugars will dry on the prism and cover which causes higher than actual readings.   Make sure you wipe off the refractometer very well with a soft, damp cloth.  I always recheck the calibration with distilled water before putting it away so that it is ready for the next time I brew.
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Offline GigaFemto

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Re: Refractometer Calibration
« Reply #4 on: February 15, 2019, 07:40:46 PM »
Every time that I have had odd refractometer readings it has been because I didn't stir the wort adequately before taking a sample. I always clean and dry the glass surface and the cover plate carefully after each reading, and I check the zero before each reading to compensate for temperature changes.

--GF

Offline Oginme

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Re: Refractometer Calibration
« Reply #5 on: February 16, 2019, 06:10:21 AM »
The best way to determine if you have stirred and homogenized the wort enough is to take several refractometer readings, stirring between each reading.  If the readings repeat, you have stirred the wort to give you consistent readings and can be assured that the reading is correct.
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