Author Topic: Refractometer  (Read 2116 times)

Offline Malticulous

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Re: Refractometer
« Reply #15 on: August 21, 2011, 08:24:44 AM »
Thanks, but I still want to taste my FG sample.

Yesterday I brewed a cream ale. Pre-boil refractometer reading was 3 points low and OG was 5 high. I understand there a many reasons why is could have been. The hydrometer simply is a better tool. Chilling 4oz does not take too long.

Offline a10t2

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Re: Refractometer
« Reply #16 on: August 21, 2011, 09:21:09 AM »
The hydrometer simply is a better tool.

Agree to disagree, then. ;)
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Offline beerdoc

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Re: Refractometer
« Reply #17 on: August 31, 2011, 08:41:10 PM »
A refractometer is not really a replacement for a hydrometer. The refractometer is faster and easier for unfermented wort, especially if it is hot (it only takes a minute to cool the  tiny sample you need for the refractometer). Each percent alcohol introduces an error of 0.4 brix which comes to 1.6 SG points. So beer with 5% alcohol by weight is going to give an error of 8 points. If  the FG is 8 pts, it's going to look like 16 pts. I would not be comfortable dealing with an error of that magnitude with a correction. Corrections are fine when the effect is a lot bigger than the correction.

Offline bluesman

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Re: Refractometer
« Reply #18 on: September 01, 2011, 05:42:05 AM »
A refractometer is not really a replacement for a hydrometer. The refractometer is faster and easier for unfermented wort, especially if it is hot (it only takes a minute to cool the  tiny sample you need for the refractometer). Each percent alcohol introduces an error of 0.4 brix which comes to 1.6 SG points. So beer with 5% alcohol by weight is going to give an error of 8 points. If  the FG is 8 pts, it's going to look like 16 pts. I would not be comfortable dealing with an error of that magnitude with a correction. Corrections are fine when the effect is a lot bigger than the correction.

Yes. I use both for this very reason. They both have their advantages and disadvantages.
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Offline gimmeales

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Re: Refractometer
« Reply #19 on: September 01, 2011, 07:28:47 AM »
A handy spreadsheet that does the corrections for you is here:  http://morebeer.com/learn_vids/vids_refract

After a couple of brews using both Refractometer and Hydrometer side-by-side (and spot checks here and there), I found the Refractometer to be dead-on and now hardly use my Hydrometer anymore.  Love the Refractometer!  (mine was one of the $25 jobs off eBay).

Offline weithman5

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Re: Refractometer
« Reply #20 on: September 01, 2011, 07:45:40 AM »
i liken this debate to one i have had regarding two other tools. my old chalk line and my new laser.  the laser does just about everything i need but once in a while it is nice to snap a chalk line.  i have not gotten a refractometer yet but when i do, i am sure that every now and then i will still want the hydrometer.
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Offline bo

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Re: Refractometer
« Reply #21 on: September 01, 2011, 07:52:22 AM »
i liken this debate to one i have had regarding two other tools. my old chalk line and my new laser.  the laser does just about everything i need but once in a while it is nice to snap a chalk line. 

Like when you're in very bright light.

Offline weithman5

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Re: Refractometer
« Reply #22 on: September 01, 2011, 08:04:54 AM »
and cutting an angle in long runs of  plywood or drywall
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Re: Refractometer
« Reply #23 on: September 01, 2011, 08:44:00 AM »
Life begins at 60.....1.060, that is!

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Offline Kit B

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Re: Refractometer
« Reply #24 on: September 02, 2011, 06:31:07 AM »
I've noticed that my correctly calibrated refractometer gives different readings, with nearly every drop of the slide cover.
I have had the same sample give me more than 3 different readings, when I'm testing my boil.
In fact, a friend of mine insists on opening & closing his cover, until he likes what he sees.
I think this is possibly a bad practice...
While I understand that he's not changing sugar content, I imagine that something has to be skewing the results, if the reading is changing...My first guess is definitely temperature, but I hypothesize that temperature is not the only culprit.
A correctly made hydrometer is the more accurate beer-making tool, IMHO.
But, it's very nice to be able to get readings during the sparge or boil.
I'm just very skeptical of how folks use the refractometer.

I have recently resorted to allowing my sample-filled refractometer sit for several minutes before I read it.
This seems to alleviate any questions regarding whether or not I can trust the measurement.
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Offline bluesman

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Re: Refractometer
« Reply #25 on: September 02, 2011, 06:46:42 AM »
When using a refractometer, one must pay attention to detail and be consistent.

Sampling boiling wort can be tricky. There can be some evaporation occurring just prior to closing the cover. Any break material that makes it way into the sample can also skew the readings.

The best way to become confident with your refractometer is to take a liter of wort (68F) and measure it with a calibrated hydrometer. Then using the same wort, start taking some readings using your refractometer. Take about ten readings and compare to your hydrometer reading. You should find that the readings will be somewhat consistent to each other and close to the hydrometer reading.
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Offline bo

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Re: Refractometer
« Reply #26 on: September 02, 2011, 06:46:54 AM »
I've noticed that my correctly calibrated refractometer gives different readings, with nearly every drop of the slide cover.
I have had the same sample give me more than 3 different readings, when I'm testing my boil.
In fact, a friend of mine insists on opening & closing his cover, until he likes what he sees.
I think this is possibly a bad practice...
While I understand that he's not changing sugar content, I imagine that something has to be skewing the results, if the reading is changing...My first guess is definitely temperature, but I hypothesize that temperature is not the only culprit.
A correctly made hydrometer is the more accurate beer-making tool, IMHO.
But, it's very nice to be able to get readings during the sparge or boil.
I'm just very skeptical of how folks use the refractometer.

I have recently resorted to allowing my sample-filled refractometer sit for several minutes before I read it.
This seems to alleviate any questions regarding whether or not I can trust the measurement.

He could very well be skewing the results. By opening the cover, you allow a little evaporation to occur. that could give you a higher than normal reading. When you place that drop on the lens it should be closed immediately and I allow mine to set for about 30 seconds before taking a reading.