Refractometer?

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jgalak

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Can a refractometer (with the appropriate conversion tables) completely replace the hydrometer for determining SG? Or is there something a hydrometer can do that a refractometer can't?

I talked to a winemaker at one point who said that it can only be used before fermentation to measure the SG changes due to sugar content, but not once fermentation started as it can't differentiate between alcohol and water. This seems counter to my understanding of how refractometers work (alcohol has a different refractive index than water), but college physics was a long time ago...
 

PistolsAtDawn

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Yes and no. The refractometer is super easy to use, only requires a fraction of the liquid that you need for a hydrometer measurement and some automatically correct for temperature (within a small range anyway).

There are correction formulas for refractometer measurements on a liquid with alcohol present. They're not perfect, but they'll get you within a point or two of what your hydrometer would read.

I would personally keep the hydrometer handy as a way to verify your refractometer is properly calibrated. But I rarely use mine since buying a refractometer.
 

hops2it

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Good answer above but I rarely use my hydrometer anymore. The conversion gets me so close, I simply don't care enough about any slight difference to break out the hydrometer, graduated cylinder and turkey baster.
 

Johnnyhitch1

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I compared my OG, FG, Mash runoff and preboil with both hydro and refractometor and come close enough 10+ times that i only use my refractometor now.
It has ATC so i leave it for about a minute with the sample on the prizm before taking a reading

I use Onebeer for my calculations after fermentation.
 
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jgalak

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Am I correct in thinking that one needs a good OG measurement to get reliable FG measurements/calculations with a refractometer? At the moment I'm limited to partial boils, so getting a good OG after mixing with the top off water is hard.
 

gr8shandini

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Yes, you need a good OG reading to get a proper FG, but that shouldn't be a problem with a partial boil. Right before pitching is the one time you're supposed to aerate the wort, so go ahead and stir and/or shake the **** out of it for a few minutes and make sure everything is mixed well.

Also, you can largely leave the tables behind as well. Unless you're brewing something really big, *Brix times 4 gives you your "gravity points" (e.g. 12 *Bx = 1.048). For the no-kidding OG reading, I'll sometimes go to the charts, but I like the in-your-head math for most of the brew day calculations.
 

hops2it

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If you've yet to purchase a refractometer, consider buying one that reads both SG and Brix. That will eliminate the need for any brew day conversion.
 

Yooper

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If you've yet to purchase a refractometer, consider buying one that reads both SG and Brix. That will eliminate the need for any brew day conversion.
That's not so. The "SG" part is so inaccurate as to be useless. It's far easier (and more accurate) to do a little math, or use a conversion table, and just use the brix on the refractometer.
 

Pratzie

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Pre boil SG, postboil OG and then after fermentation its good for measuring the stability of specific gravity using very minimal wort. U still need the hydrometer to accurately measure the FG though, because the alcohol content of the wort after fermentation messes with the refractometers ability to accurately show correct FG.
 

hops2it

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That's not so. The "SG" part is so inaccurate as to be useless. It's far easier (and more accurate) to do a little math, or use a conversion table, and just use the brix on the refractometer.
We're both talking preboil/OG here right Yooper? I have always found the gravity reading to be right on the money for unfermented wort. :confused:
 

Yooper

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We're both talking preboil/OG here right Yooper? I have always found the gravity reading to be right on the money for unfermented wort. :confused:
Not if you compare the SG/brix correctly. I forget the exact reasons, but the higher you go in brix, the more inaccurate the SG scale is on the refractometer.
 

hops2it

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Not if you compare the SG/brix correctly. I forget the exact reasons, but the higher you go in brix, the more inaccurate the SG scale is on the refractometer.
This interested me so I did some research and it seems there were some complaints about this in the past. It appears some of the newer refractometers (mine) are now using an adjusted SG scale to account for this. I was hoping this would be the case. We are looking at one horizontal line on a refractometer which intersects both a brix reading and an SG reading. If we can always trust the brix, and we know the higher gravity correction math, a working dual scale should be doable. Just need a little more or less distance between hashmarks as the brix goes up.
 

mtnagel

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Guess I need to make sure my refractometer's SG readings are correct, but if they are using the appropriate conversion formula, I don't see why the SG couldn't be correct.
 

Pratzie

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Not if you compare the SG/brix correctly. I forget the exact reasons, but the higher you go in brix, the more inaccurate the SG scale is on the refractometer.
U mean the SG is wrong when compared to the Brix on that particular refractometer? Or that as the Brix of any liquid increases, the ability of any refractometer to read accurately decrease?
 

dk21

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I've only used mine twice but am really satisfied. You have to read up on them. I was concerned after reading about a lot of negative experiences, but so far it has led me to discover that my hydrometer was off by 4 points, and after accounting for that, agrees.

The tiny sample size is great. I use a stainless 1/4 tsp that I sanitize a while before I need it so that it dries (sanitizer can impact the accuracy with such a small sample) and stick it in the flow of wort when I drain my kettle to the fermenter.
 

hops2it

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Looks like my cheap Amazon refractometer has the wrong conversion (assuming this calculator is correct).
Dang, I could have sworn I had this hurdle cleared but not so. Mine is the same scale as yours. And according to the link you posted and the one that I posted earlier (brewersfriend and homebrewstuff which use the same adjusted scaling), ours would be off. And sometimes way off. I noticed though, when I follow the link to the homebrewstuff refractometer...it claims it's adjusted for the correct scale but they also have a pic of the refractometer scale and it's wrong just like ours. I just sent them an email asking for an explanation.

And...when I enter in a brix reading on my Brewzor app (mobile phone), and set it to unfermented wort, it gives me a different reading than Beersmith which is again different from both of the links we provided here. So...WTF?? Does anybody know who's on first here? Every source seems to calculate this differently and the variance can be minimal to huge.

25 brix:
Brewzor = 1.101
My refractometer = 1.101
Beersmith = 1.104
Brewersfriend/homebrewstuff = 1.106

Houston, we have a problem. Even if we do decide to use brix as our baseline. Who's conversion is correct?
 

dk21

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It's possible that none of the conversions (alone) are correct given your refractometer. Read up on wort correction factors. If you want accuracy, you need to take comparative readings with your hydrometer to determine what your wort correction factor is. Once you know that, you can plug brix readings in along with the correction factor.
 

slaithe

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Hey! Thanks for teaching me how to properly use part of beer Smith 2!
 

Yooper

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It's possible that none of the conversions (alone) are correct given your refractometer. Read up on wort correction factors. If you want accuracy, you need to take comparative readings with your hydrometer to determine what your wort correction factor is. Once you know that, you can plug brix readings in along with the correction factor.
Yes, that makes a difference!
 

mtnagel

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I just sent them an email asking for an explanation.
Thanks for checking into it and let me know what they say.


I basically use my refractometer/hydrometer for 2 things:
1) getting OG
2) ensuring fermentation is complete

The rest isn't that important to me. Sure, knowing the % ABV is nice, but if I'm off by a percent or so, I don't really care. I'll still drink it.

For #2, it doesn't matter that the scale is off. Even though the absolute brix/SG may be wrong with the refractometer after fermentation has started, the relative number is more important to show that fermentation is complete.

For #1, I do want that to be more accurate to show I'm hitting my targets. But do I care that I'm off by 0.012 when I have a 1.129 beer? When you're that high, does it really matter? For a more typical beer for me that is supposed to be 1.065, which according to the calculator would be 15.9 brix. But if it's 15.9 brix, on my refractometer, it would read 1.062. Do I care about that 0.003 difference? Not really. The error in the reading is probably +/- 0.002 units anyway.

What's interesting is that on my last brew, I hit my pre-boil and OG numbers exactly on the SG scale, so maybe the Brix reading is off? Is that possible?

Interesting topic nonetheless. Interested to see what everyone says.
 

gr8shandini

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. . . Every source seems to calculate this differently and the variance can be minimal to huge.

25 brix:
Brewzor = 1.101
My refractometer = 1.101
Beersmith = 1.104
Brewersfriend/homebrewstuff = 1.106

Houston, we have a problem. Even if we do decide to use brix as our baseline. Who's conversion is correct?
0.005 out of 1.100 or so is a 0.5% difference. I wouldn't exactly call that a huge variance. Even if you strip off the 1.000 and just count the "points" it's 5%. And that's toward the upper end of the scale. Most of these are linear, so you're probably looking at a 2.5% error at average gravities.

Now, I don't know about you guys, but I don't think I can read my refractometer within 2.5% to begin with. Or my hydrometer for that matter. And I doubt anyone could tell the difference between a 1.048 beer and one at 1.050. So, really this is all just "in the noise" as we say where I work. I'd just pick a method that works for you and stick with it. For me, that's Brix times 4. Gets you as close as any of those other methods, anyway.
 

PistolsAtDawn

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Dang, I could have sworn I had this hurdle cleared but not so. Mine is the same scale as yours. And according to the link you posted and the one that I posted earlier (brewersfriend and homebrewstuff which use the same adjusted scaling), ours would be off. And sometimes way off. I noticed though, when I follow the link to the homebrewstuff refractometer...it claims it's adjusted for the correct scale but they also have a pic of the refractometer scale and it's wrong just like ours. I just sent them an email asking for an explanation.

And...when I enter in a brix reading on my Brewzor app (mobile phone), and set it to unfermented wort, it gives me a different reading than Beersmith which is again different from both of the links we provided here. So...WTF?? Does anybody know who's on first here? Every source seems to calculate this differently and the variance can be minimal to huge.

25 brix:
Brewzor = 1.101
My refractometer = 1.101
Beersmith = 1.104
Brewersfriend/homebrewstuff = 1.106

Houston, we have a problem. Even if we do decide to use brix as our baseline. Who's conversion is correct?
The manufacturer also made the same claim on the one I got a month or so ago on Amazon, so if you wouldn't mind posting the response you get from them, I would be appreciative!

The problem with the old SG scale on these refractometers is that it was simply Brix * 4, which doesn't work at higher gravities. Supposedly they've now corrected for that.

Another thing that I didn't see mentioned here was calibration. It's pretty crucial that you make sure the refractometer is calibrated fairly often. With RO or DI water if possible, and also checked against a hydrometer to determine the correction factor as Yooper mentioned.

Yooper, I know you've shown the math before in other threads, but would you mind giving us a quick rundown of your refractometer correction factor again? That way folks who may run across this thread in the future have what they need right here and don't have to search elsewhere.
 

mtnagel

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The problem with the old SG scale on these refractometers is that it was simply Brix * 4, which doesn't work at higher gravities. Supposedly they've now corrected for that.
Well the one I posted the picture for above is neither brix * 4 nor conversion on brewersfriend that I linked to, so I wonder what correction factor they used?

You can see mine is calibrated correctly since DI water is ready 1.000 or 0 brix.
 

PistolsAtDawn

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Well the one I posted the picture for above is neither brix * 4 nor conversion on brewersfriend that I linked to, so I wonder what correction factor they used?

You can see mine is calibrated correctly since DI water is ready 1.000 or 0 brix.
No idea, but I do know that we have the same refractometer (I saw your name on the review comments on Amazon). And when I said the manufacturer made that claim, that was assuming that the refractometer was the same one for sale on eBay. They look identical, down to the carry case, pipette and tiny screwdriver.

Like you, I just go with the Brix measurement and let my phone app do the math.
 

dmcman73

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I'm new to brewing but if you have an Android device, download and install a calculator called "Brewzor Calculator" (https://play.google.com/store/apps/details?id=com.brewzor.calculator&hl=en). It's a great little tool and has a ton of conversions in it. Click on Refractometer from the list. Once in the Refractometer calculator, there is a drop down list at the very top: unfermented wort, fermenting wort, finished beer and calibrate. The calibrate is great as you can take an initial Hydrometer reading, enter the value and then take a refractometer reading and enter that value and it will automatically adjust the correction factor for you to keep things as close as possible so you can keep using your refractometer.

The calculator also has TONS of other calculators built into as well like carbonation, strike temp, batch sparge, hop bitterness, etc. Best of all, it's free.
 

dmcman73

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Dang, I could have sworn I had this hurdle cleared but not so. Mine is the same scale as yours. And according to the link you posted and the one that I posted earlier (brewersfriend and homebrewstuff which use the same adjusted scaling), ours would be off. And sometimes way off. I noticed though, when I follow the link to the homebrewstuff refractometer...it claims it's adjusted for the correct scale but they also have a pic of the refractometer scale and it's wrong just like ours. I just sent them an email asking for an explanation.

And...when I enter in a brix reading on my Brewzor app (mobile phone), and set it to unfermented wort, it gives me a different reading than Beersmith which is again different from both of the links we provided here. So...WTF?? Does anybody know who's on first here? Every source seems to calculate this differently and the variance can be minimal to huge.

25 brix:
Brewzor = 1.101
My refractometer = 1.101
Beersmith = 1.104
Brewersfriend/homebrewstuff = 1.106

Houston, we have a problem. Even if we do decide to use brix as our baseline. Who's conversion is correct?
I'm using the Brewzor app as well. Have you calibrated the refractometer calc in it? There is an option to calibrate in the drop down menu (in the refractometer calc) where you enter a Hydrometer reading then enter the refractometer reading and it will adjust the correction value accordingly.
 

PistolsAtDawn

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I'm new to brewing but if you have an Android device, download and install a calculator called "Brewzor Calculator" (https://play.google.com/store/apps/details?id=com.brewzor.calculator&hl=en). It's a great little tool and has a ton of conversions in it. Click on Refractometer from the list. Once in the Refractometer calculator, there is a drop down list at the very top: unfermented wort, fermenting wort, finished beer and calibrate. The calibrate is great as you can take an initial Hydrometer reading, enter the value and then take a refractometer reading and enter that value and it will automatically adjust the correction factor for you to keep things as close as possible so you can keep using your refractometer.

The calculator also has TONS of other calculators built into as well like carbonation, strike temp, batch sparge, hop bitterness, etc. Best of all, it's free.
That's a good tip about the calibration and correction factor calculation. Thanks for that! I used to use that app, but I stopped once I got BrewAide (which was made by one of our forum members, Adeering). I just reinstalled Brewzor, and that's a nice function to have!
 

hops2it

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I'm using the Brewzor app as well. Have you calibrated the refractometer calc in it? There is an option to calibrate in the drop down menu (in the refractometer calc) where you enter a Hydrometer reading then enter the refractometer reading and it will adjust the correction value accordingly.
I haven't used the cal feature in Brewzor yet but I'm about to now that you mentioned it. Thanks for the idea.
 

MaxStout

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Looks like my cheap Amazon refractometer has the wrong conversion (assuming this calculator is correct). Here's a picture. 30 brix is supposed to be 1.129, but on my refractometer, it would read 1.117.

So which model did you buy? I am considering refractometers on Amazon, and might want to avoid that one if the two scales don't track.
 

TyTanium

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The ebay one is coming from China. They say it's corrected but it's clearly the same as the old one. One of the sellers even has a link saying something like "if accuracy is important to you, check out the world's most accurate refractometer, the old incorrect scale has been corrected" selling for double the price. It's the exact same refractometer. Caveat emptor
 

MaxStout

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Damn...that's the one I had my eye on. At $30, I thought it might be too good to be true.

I suppose I could just ignore the OG scale, use Brix and convert it correctly. But the fact that those two scales diverge so much makes me wonder if one or both of them might not be calibrated properly.

Anyone have a recommendation for a good, sub-$50 refractometer?
 

MaxStout

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slaithe

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That corrects the true Brix value versus the indicated value from the instrument. How does that correction account for differences indicated between the two scales?
With maths... the sg value is a function of the brix value... if you have the correct brix value you can then determine the sg value by converting it. Kind of like ferinhight and celciuse... Or maybe you could think of it like inches or cm?

Well technically neither is function of the other, the function is just the equation that lets you figure out how much eros might be in us dollers (for example), but obviously one unit is not derived from the other... just difrent amounts of "value" per base unit...
 

slaithe

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Depending on your scale, if you got a nice refractameter, you may be able to just look at the brix value and line it up... and I'm sure but there are probably lots of corrected charts out there if you don't...

The different apps calculators and web calcs throwing difforent values is kind of weird though. Has any one tried comparing them with the calibration settings/functions all set?

I really want one of theese things but their so so pricey... :-(
 

mtnagel

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Looks like I'm going to have to test between my refractometer and hydrometer. I've already done it with DI water and I did it with beer once, but I don't remember how close the numbers were. I may just do it with sugar solutions so I don't have to waste beer :)
 

MaxStout

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With maths... the sg value is a function of the brix value... if you have the correct brix value you can then determine the sg value by converting it. Kind of like ferinhight and celciuse... Or maybe you could think of it like inches or cm?

Well technically neither is function of the other, the function is just the equation that lets you figure out how much eros might be in us dollers (for example), but obviously one unit is not derived from the other... just difrent amounts of "value" per base unit...
I get the conversion between Brix and OG. My concern was not one of simple conversion between the two units; but rather, the fact that the scales did not track throughout its range. Using your analogy, it would be tantamount to a thermometer to show a correct correlation of, say, 0C/32F, but not line up 100C/212F.

In the case of the refractometer, it shows a correct alignment at 0 Brix/1.000 O.G., but the correlation diverges at higher gravities. As a previous poster noted, 30 Brix should be 1.129, but displayed as 1.117 on the refractometer. This seems to be a significant error in the scaling.
 
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