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Old 04-18-2010, 04:26 PM   #1
EricCSU
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So I brewed a pale ale this week. I've used this recipe about four times. Got the same efficiency every time.

I calibrated my refractometer after the last brew session, and assumed that it would still be calibrated two weeks later. I took a refractometer reading after my first runnings, and it was a little low. I took another reading preboil and I was 6 points low. I took another reading. Same thing.

I accepted my fate and measured out some DME before I started the boil. Threw in the DME and followed the recipe through the boil.

I finished cooling and took a hydrometer sample.

It was 6 points high.

I grabbed some distilled water and sure enough, the refractometer was blue almost all the way to the bottom of the viewer.

I will be calibrating my refractometer before every brew day from now on. And every time that I am getting an unexpected reading.

Eric
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Old 04-18-2010, 04:53 PM   #2
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I just assumed it was common practice to do this. It takes about 10 extra seconds. Of course I do this and neglect other things on my brew day, like making sure my valve is closed before I add water to my mash tun.

 
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Old 04-18-2010, 05:02 PM   #3
EricCSU
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Quote:
Originally Posted by suprchunk View Post
I just assumed it was common practice to do this. It takes about 10 extra seconds. Of course I do this and neglect other things on my brew day, like making sure my valve is closed before I add water to my mash tun.
You are correct, it should be common practice.

Just sharing a mistake so that others don't make the same one.

Eric
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Old 04-18-2010, 06:13 PM   #4
remilard
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That's weird. I calibrate mine every month or so and it is never off by more than a tenth of a degree brix, not any wider than the thickness of the lines on the scale.

To be off 12 points or 3 brix I would think your refractometer is of different manufacture than mine or somebody has been playing with the knob.

Now you can never calibrate your instruments too much, I'm not saying that, but I am surprised to here that your refractometer got that far off that fast.

 
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Old 04-18-2010, 06:17 PM   #5
smokinghole
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Each time I have recaled mine it was damn close to zero. Makes me want to check it right now since it's sitting 3 feet from me.
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Old 04-18-2010, 06:31 PM   #6
EricCSU
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Quote:
Originally Posted by remilard View Post
That's weird. I calibrate mine every month or so and it is never off by more than a tenth of a degree brix, not any wider than the thickness of the lines on the scale.

To be off 12 points or 3 brix I would think your refractometer is of different manufacture than mine or somebody has been playing with the knob.

Now you can never calibrate your instruments too much, I'm not saying that, but I am surprised to here that your refractometer got that far off that fast.
Trust me, no one was more surprised than me. I have checked it again since then and it was still at zero. Maybe it was just a fluke thing.

Eric
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Old 04-18-2010, 10:19 PM   #7
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I calibrated mine when I got it, but it didn't need calibration. I checked the calibration a few times over the next year, but it never was off. Once every 6 months or so, I check the reading against a hydrometer reading. They have always matched.
There is one possibility for your problems that I can think of. Was the refractometer at room temperature when you checked? If not, the ATC could screw up the reading.

-a.
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Old 04-18-2010, 10:29 PM   #8
Catt22
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I checked my refractometer when I used it for the first time and it was dead on. I now check it about once or twice a year and it has never required adjustment. I would think that they should hold calibration pretty well unless maybe it were dropped or was otherwise subjected to substantial shock. They are simple instruments and AFAIK, probably have only one moving part, that being the bi-metal spring mounted prism thingy. Not a whole lot to go wrong.

 
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Old 04-19-2010, 04:46 AM   #9
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Quote:
Just sharing a mistake so that others don't make the same one.
Thanks a reminder is always good. I think outside temp changes can make a difference, I calibrated inside the house(70deg.) then checked it in the garage on brew day (55 deg) yep it was off. Also I have learned to wait at least 30 seconds after putting sample on it to let the temp adj. to the refractometer.
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Old 04-20-2010, 08:44 PM   #10
schristian619
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+1 I think this is a good idea to do regularly. I keep a gallon of distilled water around and check it each brew day. It is typically at zero, but sometimes its a little off.

 
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