Refractometer

[guitarpat]

I recently purchased a beer refractometer. Upon brewing a batch of IPA, I used it for the first time to check my starting gravity. I also used my hydrometer. My refractometer reads 1.052 and the hydrometer reads 1.048. I calibrated my refractometer before use. Which one is right? or should I split the difference?

 

[bleme]

Do they both report 1.000 in water?

 

[Electrake]

+1 for bleme, check what both read in distilled water. or at least tap water

 

[Smellyglove]

I recently purchased a beer refractometer. Upon brewing a batch of IPA, I used it for the first time to check my starting gravity. I also used my hydrometer. My refractometer reads 1.052 and the hydrometer reads 1.048. I calibrated my refractometer before use. Which one is right? or should I split the difference?

If you have a hydrometer you trust, which you know is correct, trust that one. It's easier to measure incorrectly with a refractometer. The sample needs to cool down to the temperature of the refractometer itself, and if you wait to long before you measure it will show a higher reading.

There's also some cheap china ( I guess they're almost all from china?) refractometers which has the SG scale skewed, the BRIX-scale is correct, but the SG-scale is incorrect after 1.060 or so.

 

[zlimfur]

I've noticed some small derivation as well. Refractometer is showing 2-3 points less.

 

[dmtaylor]

The SG scales on refractometers are bogus. You must measure only in Brix, it is the only correct number, then use a calculator such as this one to convert to SG.

http://seanterrill.com/2012/01/06/refractometer-calculator/

FYI: You'll have to compare against a calibrated hydrometer several times to determine your own correction factor, which is unique to each refractometer. Terrill reports his friends' average of 1.04, but I know several people whose factors are closer to 1.00. The one I use is between 0.98-0.99. But once you learn the factor for your gauge, it will read accurately.

 

[brandonlovesbeer]

I keep seeing these responses that say the SG reading is never correct.
On my last batch, my refractometer SG and hydrometer reading were identical.

Do I just have a good one?

 

[Smellyglove]

My refractometer and lab grade hydrometer lines up pretty well, every time.

 

[dmtaylor]

I keep seeing these responses that say the SG reading is never correct.
On my last batch, my refractometer SG and hydrometer reading were identical.

Do I just have a good one?

Yes, you must be one of the few lucky ones.

 

[Jtk78]

Terrill reports his friends' average of 1.04, but I know several people whose factors are closer to 1.00. The one I use is between 0.98-0.99. But once you learn the factor for your gauge, it will read accurately.

For comparison, the one I use is about a 1.03 correction factor.

 

[guitarpat]

I will check my hydrometer to make sure it's calibrated. I did not do that

 

[guitarpat]

Update: I checked my hydrometer with water. Turns out that it’s off by .003That would make the reading 1.051 which is only an .001 difference. It wasn’t distilled water however. Wouldn’t the altitude make a difference too?

 

[bleme]

I always calibrate with the same water I am going to brew with. That takes the water’s weight out of the equation (sort of) so I know my numbers represent just the malt.

 

[GPP33]

The SG scales on refractometers are bogus. You must measure only in Brix, it is the only correct number, then use a calculator such as this one to convert to SG.

http://seanterrill.com/2012/01/06/refractometer-calculator/

FYI: You'll have to compare against a calibrated hydrometer several times to determine your own correction factor, which is unique to each refractometer. Terrill reports his friends' average of 1.04, but I know several people whose factors are closer to 1.00. The one I use is between 0.98-0.99. But once you learn the factor for your gauge, it will read accurately.

I keep seeing these responses that say the SG reading is never correct.
On my last batch, my refractometer SG and hydrometer reading were identical.

Do I just have a good one?

I keep reading (on HBT) that the SG scale is bogus too but it's a straight conversion, it's not like there's some black magic involved. There's no reason the manufacturer can't print the brix and SG scales correctly on the screen. In fact, if the SG scale is off then the Brix scale is probably off as well. This sounds suspiciously like an instance of one refractometer being messed up so everyone wrote off every SG scale ever printed in a refractometer. Hydrometers could easily suffer the same fate, it's just a piece of paper glued into a glass tube, not exaclty precision metrology equipment most of us are dealing with.

 

[schematix]

tl;dr: refract goes in the trash. use precision hydrometers and just deal with (gross up main batch) losing 150mL per sample.

I have lab grade precision hydrometers, and both optical and digital Brix refractometers.

When i was testing the refractometers against each other they were always exactly in agreement with each other.

The precision hydrometers are exactly that - precise. There are 3... FG=0-8.5P, Mid Range=8P-16.5P and High=16P-24.5P. I made reference solutions of sucrose at their crossover points (8P and 16P), and also checked the low one against pure water (0P) and the high one against high gravity (24P). All measured exactly spot on. I even cooled samples to check how they responded to temperature, and again, they matches *exactly* with what the correction chart said. Best value in brewing tools I've ever purchased. The standard 0.002 increment hydrometers you get for $7 for the LHBS are not precise or accurate enough to be used in conjunction with a refractometer.

On pre-boil wort there is a ~1.015-1.025 multiplier needed to convert from Brix to Plato. Every beer yields a unique conversion factor. So a measurement of 13.2 Plato would give something like 13.4 Brix. For the refract it's critical to to take measurements using clear, bubble free wort AND with wort that is the same temperature as the instrument.

Once fermentation starts you might as well put away the refract unless it's an exact rebrew where you have previous data points (and i mean exact... same recipe, same actual OG, etc). Every calculator i've ever used where i have the correction factor, along with refract and hydrometer measurements, never agree. Sometimes they are close, but sometimes they are off by A LOT. Just this past week i had one that was off by 1.5P. The refract said the beer was 1.018 (ready to rack)... so i did. But once i racked and checked a sample with the precision hydrometer it was 1.024! Hoping that doesn't come back to haunt me.

 

[schematix]

I keep reading (on HBT) that the SG scale is bogus too but it's a straight conversion, it's not like there's some black magic involved. There's no reason the manufacturer can't print the brix and SG scales correctly on the screen. In fact, if the SG scale is off then the Brix scale is probably off as well. This sounds suspiciously like an instance of one refractometer being messed up so everyone wrote off every SG scale ever printed in a refractometer. Hydrometers could easily suffer the same fate, it's just a piece of paper glued into a glass tube, not exaclty precision metrology equipment most of us are dealing with.

No the problem is that refractometers measure the index of refraction. That's what they do. They don't measure density.

There is however a very well understood relation between the concentration of SUCROSE (Brix) and refraction. There is also a very well understood relation between the concentration of sucrose and its density. Put those 2 together and you get the SG scale you see on many refracts.

In fact if you make up your own reference solutions of sucrose (or buy calibration solutions) you'll see your brix refract and plato hydrometer always agree. But when you throw beer wort at it, you are trying to measure tangerines using an orange scale. Close but different.

And then throw in the fact that the index of refraction of alcohol and sugar varies non-linearly, you are now using the orange measuring tool on an apple.

 

[MX1]

I have lab grade precision hydrometers, and both optical and digital Brix refractometers.

When i was testing the refractometers against each other they were always exactly in agreement with each other.

The precision hydrometers are exactly that - precise. There are 3... FG=0-8.5P, Mid Range=8P-16.5P and High=16P-24.5P. I made reference solutions of sucrose at their crossover points (8P and 16P), and also checked the low one against pure water (0P) and the high one against high gravity (24P). All measured exactly spot on. I even cooled samples to check how they responded to temperature, and again, they matches *exactly* with what the correction chart said. Best value in brewing tools I've ever purchased. The standard 0.002 increment hydrometers you get for $7 for the LHBS are not precise or accurate enough to be used in conjunction with a refractometer.

Where did you get your hydrometers. I need good ones that are easy to read too.....beer and age are killing my eyesight. LOL

 

[GPP33]

tl;dr: refract goes in the trash. use precision hydrometers and just deal with (gross up main batch) losing 150mL per sample.

I have lab grade precision hydrometers, and both optical and digital Brix refractometers.

When i was testing the refractometers against each other they were always exactly in agreement with each other.

The precision hydrometers are exactly that - precise. There are 3... FG=0-8.5P, Mid Range=8P-16.5P and High=16P-24.5P. I made reference solutions of sucrose at their crossover points (8P and 16P), and also checked the low one against pure water (0P) and the high one against high gravity (24P). All measured exactly spot on. I even cooled samples to check how they responded to temperature, and again, they matches *exactly* with what the correction chart said. Best value in brewing tools I've ever purchased. The standard 0.002 increment hydrometers you get for $7 for the LHBS are not precise or accurate enough to be used in conjunction with a refractometer.

On pre-boil wort there is a ~1.015-1.025 multiplier needed to convert from Brix to Plato. Every beer yields a unique conversion factor. So a measurement of 13.2 Plato would give something like 13.4 Brix. For the refract it's critical to to take measurements using clear, bubble free wort AND with wort that is the same temperature as the instrument.

Once fermentation starts you might as well put away the refract unless it's an exact rebrew where you have previous data points (and i mean exact... same recipe, same actual OG, etc). Every calculator i've ever used where i have the correction factor, along with refract and hydrometer measurements, never agree. Sometimes they are close, but sometimes they are off by A LOT. Just this past week i had one that was off by 1.5P. The refract said the beer was 1.018 (ready to rack)... so i did. But once i racked and checked a sample with the precision hydrometer it was 1.024! Hoping that doesn't come back to haunt me.

Do you actually make adjustments to hit very specific numbers? Diluting would be easy but what about increasing the gravity? Once you have added hops you can't exactly boil it down, do you just add DME?

 

[schematix]

Where did you get your hydrometers. I need good ones that are easy to read too.....beer and age are killing my eyesight. LOL

LHBS. You can find them online but they are a bit pricier than what i paid for the exact same thing.... you may only need the low and mid range depending upon what you brew. If i remember later i will try to dig up a link to what they are exactly.

 

[MX1]

LHBS. You can find them online but they are a bit pricier than what i paid for the exact same thing.... you may only need the low and mid range depending upon what you brew. If i remember later i will try to dig up a link to what they are exactly.

I found a set of 3 on Amazon, not to $$$$$

 

[schematix]

Do you actually make adjustments to hit very specific numbers? Diluting would be easy but what about increasing the gravity? Once you have added hops you can't exactly boil it down, do you just add DME?

No i never adjust on the fly. I understand the math and malt analysis well enough to usually hit within a point.

Just yesterday i made a new recipe that i hoped to hit 16P. Final-final was 15.8P, less than 1 SG point off. Not sure i can measure my water volumes precisely enough to do much better.

 

[schematix]

I found a set of 3 on Amazon, not to $$$$$

I paid around $110 for all 3, if that's a good reference.

 

[schematix]

I should also note you want narrow range hydrometers.... a spread of roughly 8-9P (32-36 gravity points) or less is better. The problem with the $7 hydrometers is that the full range covers like -2P to 35P. A single increment is too hard to discern.

 

[Sailingeric]

Update: I checked my hydrometer with water. Turns out that it’s off by .003That would make the reading 1.051 which is only an .001 difference. It wasn’t distilled water however. Wouldn’t the altitude make a difference too?

Altitude should not make a difference but the temp of your water would. I use a refractometer and I am happy with it and it was zeroed out with distilled water but my hydrometer was off by a couple points. Since I got a refractometer my hydrometer has been living in a drawer. I am just look at when I finish my batch so I know how my efficiency when and what to expect ABV based on my yeast I am using. I don't check my finished product since I get beer in the end and if it really turned out to be 6.3% instead of 6.5% I am not going to sweat it.

 

[schematix]

There are 2 common temperature ratings out there for hydrometers.... 60F and 68F (20C). Make sure you know which kind you have!

I really like the precision ones i have too because they have an integrated thermometer with the correction scale built right into it. Simply take the reading, add the offset and done.

 

[GPP33]

No the problem is that refractometers measure the index of refraction. That's what they do. They don't measure density.

There is however a very well understood relation between the concentration of SUCROSE (Brix) and refraction. There is also a very well understood relation between the concentration of sucrose and its density. Put those 2 together and you get the SG scale you see on many refracts.

In fact if you make up your own reference solutions of sucrose (or buy calibration solutions) you'll see your brix refract and plato hydrometer always agree. But when you throw beer wort at it, you are trying to measure tangerines using an orange scale. Close but different.

And then throw in the fact that the index of refraction of alcohol and sugar varies non-linearly, you are now using the orange measuring tool on an apple.

Agreed on alcohol throwing the numbers off. Using the SG scale on the refractometer is no different than using the brix then doing a manual conversion to SG though, unless I missing something. Provided of course the manufacturer printed it correctly.

I guess my point is that Brix and Plato both suffer the same shortcomings as SG when it comes to estimating the weight of fermentable and unfermentable sugar dissolved in wort by trying to measure the index of refraction and comparing it to the overall density. It's not at all surprising that refractometer readings often don't agree with hydrometer readings regardless of the chosen scale since you are measuring two different characteristics. For most of us it's close enough though.

 

[schematix]

Agreed on alcohol throwing the numbers off. Using the SG scale on the refractometer is no different than using the brix then doing a manual conversion to SG though, unless I missing something. Provided of course the manufacturer printed it correctly.

I guess my point is that Brix and Plato both suffer the same shortcomings as SG when it comes to estimating the weight of fermentable and unfermentable sugar dissolved in wort by trying to measure the index of refraction and comparing it to the overall density. It's not at all surprising that refractometer readings often don't agree with hydrometer readings regardless of the chosen scale since you are measuring two different characteristics. For most of us it's close enough though.

In a world of only hydrometers, SG vs Brix vs Plato doesn't matter because they all measure relative density (what brewers really care about).

It's only when the refractometer is introduced do things get clunky.

 

[MX1]

Brewery Essentials Herculometer Advanced Gravity Testing Set of Shatterproof Precision Home Brewing and Wine Making Hydrometers - Three Different Precision Scales https://www.amazon.com/dp/B071RNC3J6/?tag=skimlinks_replacement-20

 

[schematix]

Nay.

Well second round of googling was successful. You want these 3:

http://www.novatech-usa.com/Products/Balling-Plato-Hydrometers/6614TS-5.html
http://www.novatech-usa.com/Products/Balling-Plato-Hydrometers/6614TS-6.html
http://www.novatech-usa.com/Products/Balling-Plato-Hydrometers/6614TS-7.html

 

[GPP33]

No i never adjust on the fly. I understand the math and malt analysis well enough to usually hit within a point.

Just yesterday i made a new recipe that i hoped to hit 16P. Final-final was 15.8P, less than 1 SG point off. Not sure i can measure my water volumes precisely enough to do much better.

Ok, that's where I've always gotten stuck on the purchase price of these. Like I said, they'd be cool to have, but at the end of the day they won't make a difference in how I brew (wasn't sure if I was missing some great opportunity there). Much like my Ph meter, I get the data to see how close I got to my goal but it's really nothing more than entertainment for me since I know I'm going to be within a couple points on by OG and FG and regardless of the result I'm going to forge ahead. If you routinely brew the same recipe you can use them to fine tune to achieve the perfect numbers but at some point that's just entertainment as well since I doubt you can tell the difference between a beer with an OG of 1.055 and an OG of 1.056. The precision FG one could be good if you bottle and are prone to using finicky yeasts I guess.

 

[schematix]

Ok, that's where I've always gotten stuck on the purchase price of these. Like I said, they'd be cool to have, but at the end of the day they won't make a difference in how I brew (wasn't sure if I was missing some great opportunity there). Much like my Ph meter, I get the data to see how close I got to my goal but it's really nothing more than entertainment for me since I know I'm going to be within a couple points on by OG and FG and regardless of the result I'm going to forge ahead. If you routinely brew the same recipe you can use them to fine tune to achieve the perfect numbers but at some point that's just entertainment as well since I doubt you can tell the difference between a beer with an OG of 1.055 and an OG of 1.056. The precision FG one could be good if you bottle and are prone to using finicky yeasts I guess.

I spund every beer so it’s important to know exactly where I am at. That’s why I don’t rely on a refract.

At one point I owned 3 $7 hydrometers that would measure a difference of *6* points high to low. How the heck can you tell what’s going on with that much error? With these I know they are spot on, every time.

So yah not strictly required, but if you want to maximize value of brewery tools I’d say get the precision hydro set and an simple optical Brix refract. Digital refract wasn’t worth the money in my opinion. Put that money towards a pH meter.

 

[MX1]

Thinking I will get the set I linked

 

[schematix]

Want me to talk you out of it or are you set???

 

[MX1]

Is there someone wrong with that set, other than it is from NB

 

[doug293cz]

Is there someone wrong with that set, other than it is from NB

The set you linked is more precise than a wide range hydro, but less precise than the three that @schematix listed. I have a 1.000 to 1.070 hydrometer, and it can be read to 0.0005. That's good enough for me. It's all about how accurate you think you need to be to be happy with your process. Don't let anyone tell you you have to pick one particular option if there are several valid ones to achieve what you are after (not everyone values the different metrics equally.)

Brew on

 

[doug293cz]

I spund every beer so it’s important to know exactly where I am at. That’s why I don’t rely on a refract.

...

Why is extra accuracy important when spunding? Can't you just put the beer in the spunding vessel with an extra cushion of remaining fermentables, and let the spunding valve take care of preventing over-pressure? Am I missing something?

Now if you were trying to "spund" in glass bottles, that would be a different thing, but you would still have a large uncertainty about just what FG would actually be achieved.

Brew on

 

[schematix]

That $50 set of 3 has a decent FG hydrometer but the others are pretty coarse and really not a whole lot better than the $7 LHBS one.

If you ever intend to use the hydrometer reading to correlate a fermentation refract reading you'll find that even 1 or 2 gravity points in OG error makes a fairly large difference in the estimated gravity.

The reason i'd go with the more expensive set of 3 (or at least low and mid range depending upon what you brew) is they have the integrated thermometer with the correction offset built in. I had no idea about how awesome this was when i bought it.

 

[MX1]

Nay.

Well second round of googling was successful. You want these 3:

http://www.novatech-usa.com/Products/Balling-Plato-Hydrometers/6614TS-5.html
http://www.novatech-usa.com/Products/Balling-Plato-Hydrometers/6614TS-6.html
http://www.novatech-usa.com/Products/Balling-Plato-Hydrometers/6614TS-7.html

Thanks for the links.
I first want to say that I am in no way disregarding your input, but I feel like the ones you linked to may be a bit more than I really need, and I also want SG for ease of use. I am looking on the site you linked to for the right SG hydrometers.

 

[schematix]

Thanks for the links.
I first want to say that I am in no way disregarding your input, but I feel like the ones you linked to may be a bit more than I really need, and I also want SG for ease of use. I am looking on the site you linked to for the right SG hydrometers.

You may try to look elsewhere as well for similar products. I paid about $30 a piece for mine at the LHBS, so I know they can be found cheaper....

My advice is worthless (as in free). Take it for what it is. Doesn't bother me if you go another direction. IMO/IME the slightly more expensive tools are worth the price because they do more, do it better and you only end up buying them once. I understand money is a bigger concern for some people. This is one tool i KNOW i won't be buying again.

 

[MX1]

Free and worthless are 2 different things