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Home Brew Forums > Home Brewing Beer > Beginners Beer Brewing Forum > Refractometer
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Old 12-06-2013, 07:04 PM   #21
ajdelange
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I think there is some misunderstanding here. It is when a refractometer is used to measure ABV that it needs to be calibrated for the family of beers. If you have a lab with a densitometer or pycnometer but don't want to have to do all that work for each gyle you come up with a calibration curve for each beer in the profile an can, using that, quickly estimate ABV, in the cellar, on each batch. Of course a modern lab isn't equipped with a densitometer. It is equipped with an Alcolyzer. Just put a sample bottle with a few mL in the carousel and ABV, TE, OG, ADF, RDF, AE... are all sent to your computer.

The problem with the use of refractometers WRT wort is that most of the time they read within 1 °P. But sometimes they are in error by more than 1, as much a 2 Bx or even more (an example would be the gent who read 2.6 on his tea with no sugar in it) and the only way to know is by checking against a hydrometer and if you do that then what's the point in having the refractometer? But if you are OK with potential error of 1 Bx most of the time and occasionally being off by more than that, a refractometer may be fine for you.

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Old 12-06-2013, 09:13 PM   #22
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Anyone got any info on how to use the ones with a v/v scale yet?

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Old 12-06-2013, 10:03 PM   #23
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I have had a wonderful experience with my refractometer, and have personally found the final gravity point difference between my refractometer and my hydrometer to be minimal, acceptable, and well within the range of error of reading my hydrometer. I have been collecting comparative data on FG sample readings so I can have a clearer idea of the range of error I might be looking at when using a refractometer to determine FG. With one exception, I have found the FG point difference to be <=1 gravity point (e.g. 1.015 vs 1.014), and frequently I've seen 0-0.5 point differences. I've posted this elsewhere but I have since added a few data points.

Code:
                   | DH20   | ESB     | RedAle  | BelgPA | CalComB | SWinSai | SSumSai | BGoldStr | CrmAle  | BDarkStr | BelgIPA | VnaLgr
-------------------|--------|---------|---------|--------|---------|---------|---------|----------|---------|----------|---------|-------
Sample temp        | 60.0   | 59.7    | 59.9    | 60.3   | 60.1    | 59.7    | 59.8    | 72.5     | 66      | 71.8     | 60.3    | 60.2
OG (Brix)          | 0      | 14.6    | 13.75   | 14.2   | 13      | 18.4    | 14.5    | 18.6     | 12      | 22.5     | 16.1    | 14.2
OG (SG)            | 0      | 1.058   | 1.054   | 1.056  | 1.051   | 1.074   | 1.058   | 1.075    | 1.047   | 1.092    | 1.064   | 1.056
FG (Brix)          | 0      | 8.0     | 6.6     | 7.0    | 6.95    | 8.4     | 6.6     | 7.8      | 6.1     | 11.0     | 7.8     | 7.2
FG (Beersmith)     | 0      | 1.015   | 1.009   | 1.010  | 1.013   | 1.008   | 1.006   | 1.004    | 1.010   | 1.014    | 1.010   | 1.012
FG (Hydrometer)    | 1.0000 | 1.0145  | 1.0105  | 1.0100 | 1.0125  | 1.0090  | 1.0070  | 1.0040   | 1.0105  | 1.0150   | 1.0100  | 1.0120
Gravity Difference |        | 0.5     | 1.5     | 0      | 0.5     | 1       | 1       | 0        | 0.5     | 1        | 0       | 0
I believe that the precision of your reading is very important when using a refractometer for both the OG and FG, and taking the reading from the top of the fuzzy line is equally important. The lines can be VERY close in a refractometer and account for 0.2 Brix difference in readings, and I make every attempt to get my reading down to the [mid-point] hundredths decimal place. Some things I do is make sure to let the line become clear and distinct; wait a minute or two to ensure identical readings; and turn the refractometer upside-down to get greater contrast.

I'll continue to take comparative readings over time and will keep adding data points to my dataset, but I don't worry much about my corrected FG readings that I obtain from beersmith. BTW, I have found much closer and more frequent corresponce between corrected readings using BeerSmiths refractometer tool versus Sean Terrills.

When using a refractometer, the line can be quite fuzzy at times. I have found the best place to obtain the readings is from the top of the fuzzy line as shown in this example:
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Reason: 0.2 brix, of course :)
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Old 12-06-2013, 11:24 PM   #24
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Hmm. I never thought to turn the refractometer over to make it easier to read. I'll have to give that a try next time.

Also, minor nitpick, but I think you meant to say that each small line is 0.2 Brix. If it was 2, it'd be so hard to read as to be almost useless.

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Old 12-07-2013, 01:44 AM   #25
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Quote:
Originally Posted by gr8shandini View Post
Hmm. I never thought to turn the refractometer over to make it easier to read. I'll have to give that a try next time.

Also, minor nitpick, but I think you meant to say that each small line is 0.2 Brix. If it was 2, it'd be so hard to read as to be almost useless.
Good catch!! I did mean 0.2 brix
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Old 12-08-2013, 10:52 PM   #26
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Quote:
Originally Posted by PRE66_6TART View Post
I just ordered my refractometer before stumbling across this thread. Now I'm wondering if I wasted my money. I've never heard that they needed to be calibrated for different beers styles. I'm a little lost on the details though. What is the margin of error we are talking about? I only brew ales if that makes a difference.
I read this on Friday, but was brewing today, so, I decided to hold off on my response until today. I have checked my refractometer now 3 times against my hydrometer. All 3 times it has been spot on. It had been a while since I checked it and the other two times were against fairly light colored wort. Today I was brewing an IPA that was a bit darker on the scale and wanted to check it on that. Again, spot on.

Now, I don't use it for FG, Just pre-boil, OG and tests during the boil to make sure I'm going to be hitting my numbers. I always calibrate it with distilled water, then leave it on the counter in my kitchen, where I calibrated it. LIving in the midwest, it's not uncommon to have good sized temperature swings outside during the brew, so I always just put a little in a cup and then set it on counter to adjust to the calibrated temp. So, mine, an inexpensive one at that, seems to work great.

As I said though, I don't use it for FG readings. Seems that's where the real variations start. Personally though, I like to use the Hydro sample for FG as a taste test, to make sure everything is coming together correctly.
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