Author Topic: Refractometer Calibration  (Read 2291 times)

musseldoc

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Refractometer Calibration
« on: November 25, 2014, 12:42:41 PM »
Anyone have trouble with their refractometer losing its calibration?  It seems every time I go to use mine, it seems to be off by ~1 Brix.  At first I thought it was differences in the DOC of the source water I was using, but then I started calibrating with distilled water and the problem still exists.  Basically, I clean with tap, dry, then place 3 drops of distilled on the prism, then turn the dial so the blue line crosses at zero.  Seems simple enough.  Yesterday, I calibrated at the beginning of the brew day and by the end of the day it was off by 1 Brix again.  I have tried everything short of throwing it to intentionally try to get it to lose its calibration with no success.  But, sure as I leave it sit for a day, it's off again.  Is there a locking mechanism or something that I need to use once I turn the dial when I calibrate?  Any ideas on whats going on? 

Offline Stevie

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Re: Refractometer Calibration
« Reply #1 on: November 25, 2014, 12:53:33 PM »
I have read in Amazon reviews that the cheap ones will fall out of calibration. So far mine is good.

Offline erockrph

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Re: Refractometer Calibration
« Reply #2 on: November 25, 2014, 01:09:33 PM »
I got a real cheap dual scale one on Amazon and it's almost always dead-on. The water you're using to calibrate is at the proper temp, right?
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Offline HoosierBrew

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Re: Refractometer Calibration
« Reply #3 on: November 25, 2014, 01:09:41 PM »
I must be lucky. I bought one of the $40-50 ones from Amazon and the thing is rock solid. I check calibration with distilled every time and it doesn't drift. And the readings are consistent. I've heard stories of readings being all over the place with some, but I check each sample 2 or 3 times to check consistency and it's good there. I still use a hydrometer for FG, but I love the thing.
Jon H.

Offline David Lester

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Re: Refractometer Calibration
« Reply #4 on: November 25, 2014, 02:52:05 PM »
Temperature variations might be your issue. Check first to see if your refractometer works correctly at any temperature. By the way, why is being off by 1 point a bad thing? Every meter has its variations.



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dLester

Offline tommymorris

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Re: Refractometer Calibration
« Reply #5 on: November 25, 2014, 03:27:36 PM »
Temperature variations might be your issue. Check first to see if your refractometer works correctly at any temperature. By the way, why is being off by 1 point a bad thing? Every meter has its variations.



Cheers,
dLester
1 Brix is about 4 specific gravity points.  I think that is more than minor variation. That's 10% for a 10 Brix brew. Most measuring tools are more accurate than +/- 10%.

Offline reverseapachemaster

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Re: Refractometer Calibration
« Reply #6 on: November 25, 2014, 03:57:23 PM »
Does the refractometer always stabilize at exactly the same point 1 brix low or high? If so, I'd think about not fighting against the refractometer and just add/subtract one brix in my calculation to determine gravity rather than recalibrating each time you use it.
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musseldoc

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Re: Refractometer Calibration
« Reply #7 on: November 25, 2014, 05:58:57 PM »
I definitely thought about temperature.  I calibrated yesterday morning when it was ~55F, then it was off calibration after the air had cooled to ~35F that evening.  So, I held the refractometer in my hand for several minutes to warm it back up, and the calibration was still off.  For OG, 1 brix isn't such a big deal, but for FG it affects the calculation for FG by quite a bit. 

Offline a10t2

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Re: Refractometer Calibration
« Reply #8 on: November 25, 2014, 06:29:44 PM »
If it's one of the cheap Chinese ones, I think the tolerances on the ATC springs are not great, and that's why some people have issues. Unfortunately, mine is always dead on, so I haven't done any troubleshooting on the problem.

I'd say just bite the bullet and spend the $25 for a new one. If an instrument can't be calibrated, it isn't useful.
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Offline Slowbrew

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Re: Refractometer Calibration
« Reply #9 on: November 25, 2014, 07:00:09 PM »
Sorry to hear about your issue. 

I bought mine years ago (on ebay, I think) and have never had to adjust it.  I'm feeling pretty luck at this point.

Paul
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Offline blatz

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Re: Refractometer Calibration
« Reply #10 on: November 25, 2014, 07:10:47 PM »
been using mine for about 5 years now, and i check it with a hydro everytime and i've never messed with the calibration since the first month or two since i bought it.
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Offline denny

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Re: Refractometer Calibration
« Reply #11 on: November 25, 2014, 07:14:05 PM »
I have 2 and I've given up on using them.  No matter how I calibrate, I can't get them to agree with each other or my hydrometer.
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Offline blatz

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Re: Refractometer Calibration
« Reply #12 on: November 25, 2014, 07:35:45 PM »
I have 2 and I've given up on using them.  No matter how I calibrate, I can't get them to agree with each other or my hydrometer.

i heard they don't work in oregon  :P
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Offline denny

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Re: Refractometer Calibration
« Reply #13 on: November 25, 2014, 08:01:19 PM »
I have 2 and I've given up on using them.  No matter how I calibrate, I can't get them to agree with each other or my hydrometer.

i heard they don't work in oregon  :P

So THAT'S it!
Life begins at 60.....1.060, that is!

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Offline yso191

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Re: Refractometer Calibration
« Reply #14 on: November 26, 2014, 02:05:14 AM »
I brewed an American Brown Ale today.  I often don't take a preboil gravity reading, but I thought I would today.  I stirred the wort in the boil kettle after sparging and took a sample.  My refractometer read 1.032!  It should have been 1.041.  So I'm thinking about adding DME.

But I thought I should take another sample and reading.  Stirred again, drew my sample and it read 1.043.  Nice.

But I thought I better get 2 samples alike so I stirred again, sampled... and it read 1.055!

I'm thinking it would be immoral for me to sell the refractometer.

Oh.  With the hydrometer my OG was 1.052.  Beersmith predicted 1.051. 
Steve
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