Does it matter what kind of refractometer we get?

[Elysium82]

Hey guys,

So, it feels like ATC (temperature adjustment) is a basic feature when it comes to refractometers(at least with the ones I have found so far).
However, there are tons of different types (depending on what you make or have), but I guess we just have to go for the one that says it is good for wort, but are there any other features we should be careful with?

1, I see a lot of no name (without any brand name) refractometers. Are they equally good as the similarly priced ones that come with a brand name? I dont know if, say, they break earlier or come with lower quality.
2, Does the actual scale they come with matter? I will insert a photo. This one shows the Brix and the SG too.. It feels super handy. No conversion is required then, but is SG measure as accurate as the Brix one?

 

[DBhomebrew]

2. A refractometer measures specific gravity indirectly through refraction. Pre-pitch, you could use the SG scale. Post-pitch, the reading  must be run through a calculator. I prefer to read and note all refractometer readings as Brix then run it through the calculator to find the adjusted reading in SG. In my notes, I know a Bx reading is raw refractometer data. SG notations have been adjusted. Long story short, my refractometer has a SG scale which I do not use.

1. My refractometer cost about $15, no name, off Amazon. It holds calibration well. Lab grade, it is not.

 

[Elysium82]

2. A refractometer measures specific gravity indirectly through refraction. Pre-pitch, you could use the SG scale. Post-pitch, the reading  must be run through a calculator. I prefer to read and note all refractometer readings as Brix then run it through the calculator to find the adjusted reading in SG. In my notes, I know a Bx reading is raw refractometer data. SG notations have been adjusted. Long story short, my refractometer has a SG scale which I do not use.

1. My refractometer cost about $15, no name, off Amazon. It holds calibration well. Lab grade, it is not.

Thank you.
1, yeah...that is what I thought, but then the SG scale in a way is a total waste of space and the Brix scale could be made bigger so that we could see it better. Hm....

 

[Zambezi Special]

Just check the range...
I bought one that is way of for brewing beer. Probably more for jam & honey. Luckily it wasn't expensive so I kept it.
The one I use now goes up to 20 brix. Not good if you want a real high ABV beer, but nice as the scale is stretched out

 

[wallyLOZ]

I've also got a cheap refractometer with SG and Brix scales. I compared the readings of the refractometer and a hydrometer side by side for several batches. Never had more than a 2 point difference. Close enough for me. The hydrometer is now mothballed.

Don't forget to check the calibration every time you use it with distilled water. Cheers!

 

[DuncB]

I splashed out on a Milwaukee electronic one which although costly was a lot cheaper than an easy dens.

I use the hydrometer for OG and FG as a cross check with refractometer, just for old times sake really. The refractometer just works great. I also take far more readings during brewday than before which has helped a lot with my process.

 

[dmtaylor]

1) I use a cheap one. It works great, it consistently reads within 0.001-0.002 average versus a standard hydrometer.

2) Do not trust the SG scale, it is notoriously inaccurate.

In both cases, it is critical that you use a conversion calculator. This one is the most accurate of all, and user-friendly:

https://www.brewersfriend.com/refractometer-calculator/

 

[Thorrak]

I splashed out on a Milwaukee electronic one which although costly was a lot cheaper than an easy dens.

I use the hydrometer for OG and FG as a cross check with refractometer, just for old times sake really. The refractometer just works great. I also take far more readings during brewday than before which has helped a lot with my process.

Having had both an easy dens-equivalent digital hydrometer and a digital refractometer, I have to say, that while I prefer the digital hydrometer due to the ability to avoid having to use a calculator post-fermentation, either are preferable to manual refractometer/hydrometers for exactly the reason you cite. More frequent measurements with less liquid are better than less frequent measurements, or measurements that require more liquid.

If you can afford the easy dens (or another digital hydrometer!) I highly recommend one, but at 1/3 the cost, a digital refractometer is a great investment.

 

[DuncB]

@Thorrak
Let's hope that both digital hydrometers and digital refractometers come down in price and perhaps size. Surely a Bluetooth dig refractometer with phone software and built in conversion can't be far away. Or plug in for power and data via USB C.

 

[jambop]

I bought a cheap refracometer from Amazon and extensive testing proved it to be almost bang on what my hydrometer reads... it is totally useless for fermented wort though so final gravity's are made with the hydrometer I am not going to waste time calibrating different wort/ alcohol concentrations.
for me the major issue with refracts is they really require a clear liquid for best results a hydrometer can read wort with any amount of crap in it.

 

[bracconiere]

just make sure it reads brix, and not ABV, or salinity!

 

[DuncB]

@jambop
Why do you say useless for fermented wort?
Provided you know the original brix of a fermented or part fermented wort and the brix reading fermented the calculators will convert to an accurate SG gravity reading.
You must have calibrated a correction factor before this which is a one time procedure.
I use the brewfather software which will guide you through calibration as well.

 

[DuncB]

just make sure it reads brix, and not ABV, or salinity!

Otherwise it's insanity.

 

[citrainmyhefeweizen]

Does the actual scale they come with matter?

As long as the device has a Brix scale, you should be good to go. According to Sean Terrill, the SG scale on cheap handheld devices has been notoriously inaccurate in the past. But as someone already said, you can only use the SG scale for measuring OG anyway. For FG measurements you need a correlation function. Terrill Linear and Novotny Linear are the widely among them. While Novotny gives reasonable results throughout fermentation, Terrill does not until the end of fermentation. I own a cheap handheld refractometer and also a Milwaukee MA885. The cheap device gives comparable readings. It's just that the scale is very difficult to read for me. If the line of projected refractive index blurs, there is trub in the sample.

The ATC is a somewhat problematic function because it is calibrated for sucrose solutions and not for wort, which causes additional errors. Before measuring, always allow the refractometer to warm up to room temperature and perform a calibration (correctly an adjustment) with de-ionized water.

It is notoriously easy to get a bad reading with a refractometer because the sample size is so small. Especially after lautering, ensure that the wort is well mixed. Draw a small sample into a container with a lid. When hot, let it cool down with with the lid on. Never drop a hot sample directly on the refractometer. After fermentation, let the yeast settle out and try to remove CO2 by shaking or another method.

Since wort is not a pure sucrose solution, you should ideally calibrate the wort correction factor (WCF) with another measuring device such as a hydrometer. This factor compensates the error. Typically you could set it to 1.03, accounting for a deviation of 3%.

If you have a deepter interest in the topic, I have written an article about refractometer calculations and also implemented a refractometer calculator. Unfortunately the article is written in German and also uses mass percent instead of specific gravity for the most part but you could give the machine translated version a try (see attachment). You will find my calculator here: Refractometer-Calculator. OG will be displayed in parentheses as "Original Extract" and FG in parentheses as "Apparent Extract". For fire and forget set the "Correlation" to "Terrill & Novotny".

 

[dmtaylor]

As long as the device has a Brix scale, you should be good to go. According to Sean Terrill, the SG scale on cheap handheld devices has been notoriously inaccurate in the past. But as someone already said, you can only use the SG scale for measuring OG anyway. For FG measurements you need a correlation function. Terrill Linear and Novotny Linear are the widely among them. While Novotny gives reasonable results throughout fermentation, Terrill does not until the end of fermentation. I own a cheap handheld refractometer and also a Milwaukee MA885. The cheap device gives comparable readings. It's just that the scale is very difficult to read for me. If the line of projected refractive index blurs, there is trub in the sample.

The ATC is a somewhat problematic function because it is calibrated for sucrose solutions and not for wort, which causes additional errors. Before measuring, always allow the refractometer to warm up to room temperature and perform a calibration (correctly an adjustment) with de-ionized water.

It is notoriously easy to get a bad reading with a refractometer because the sample size is so small. Especially after lautering, ensure that the wort is well mixed. Draw a small sample into a container with a lid. When hot, let it cool down with with the lid on. Never drop a hot sample directly on the refractometer. After fermentation, let the yeast settle out and try to remove CO2 by shaking or another method.

Since wort is not a pure sucrose solution, you should ideally calibrate the wort correction factor (WCF) with another measuring device such as a hydrometer. This factor compensates the error. Typically you could set it to 1.03, accounting for a deviation of 3%.

If you have a deepter interest in the topic, I have written an article about refractometer calculations and also implemented a refractometer calculator. Unfortunately the article is written in German and also uses mass percent instead of specific gravity for the most part but you could give the machine translated version a try (see attachment). You will find my calculator here: Refractometer-Calculator. OG will be displayed in parentheses as "Original Extract" and FG in parentheses as "Apparent Extract". For fire and forget set the "Correlation" to "Terrill & Novotny".

Very nice. I like that you have 7 different equations in there for ease of comparison. I have 5 of the 7 in spreadsheet format. Most end up with results within 0.001-0.002 of one another. Terrill is the one that is more often an outlier. That being said, I find Terrill is the most accurate when finishing gravity (FG) is less than 1.014. For higher FG, I will use one of the other calculators.

 

[citrainmyhefeweizen]

Thanks!

Very nice. I like that you have 7 different equations in there for ease of comparison. I have 5 of the 7 in spreadsheet format. Most end up with results within 0.001-0.002 of one another. Terrill is the one that is more often an outlier. That being said, I find Terrill is the most accurate when finishing gravity (FG) is less than 1.014. For higher FG, I will use one of the other calculators.

Thanks! I guess you are missing Gardner and Gossett? Gardner's correlation was referenced in Bonhams Zymurgy Article and is simply SG=1.53*bx_f-0,59*bx_i/wcf. The Gossett one is a bit more complex. A detailed description can be found on his homepage: Derivation. I would really like to add the one to my list that is used by Anton Paar in their inline refractometers for fermentation monitoring, but I doubt that they will ever release it to the gerneral public. I think I have learned about this threshold in a Redit post. In my calculator I simply compute the mean of the Terrill and Novotny equation and when it is below 1.014 I go by Terrill. Kind of a hack, but it gave a better correlation to my data set than Terrill or Novotny on their own.

 

[dmtaylor]

I think I have learned about this threshold in a Redit post. In my calculator I simply compute the mean of the Terrill and Novotny equation and when it is below 1.014 I go by Terrill. Kind of a hack, but it gave a better correlation to my data set than Terrill or Novotny on their own.

Indeed, Terrill (a10t2) and I were the ones discussing this on the old Reddit thread. I didn't know anyone else was listening.



On my spreadsheet, I have Gossett. I have not seen Gardner before.

 

[CascadesBrewer]

2) Do not trust the SG scale, it is notoriously inaccurate.

That is something I have noticed with my cheapo Amazon refractometer. I am not sure what formula is used for the conversion from Brix to SG, but it did not match up with the few calculators I tried. As I recall, it was close in the 1.050 range, but significantly off at higher gravities. I just use the Brix reading and plug that into the conversion tool in BeerSmith (which includes a correction factor).

 

[citrainmyhefeweizen]

On my spreadsheet, I have Gossett. I have not seen Gardner before.

The original source for Gardner's equation is: Gardner, S., "Enhanced Utilization of Hand Refractometers in Brewing Operations", The New Brewer, July-August 2000. Vol 17. No. 4. p 44. Unfortunately, I do not have access to this publication but this equation was also presented in: Bonham, L. K., "The Use of Handheld Refractometers by Homebrewers", Zymurgy, 2001. Vol. 24 No. 1. p 43-46. This article I can provide to you.