Who Do You Trust? Hydrometer or Refractometer

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So I have two perfectly calibrated instruments that read dead on in distilled water at the correct temperature, but when they get up into the 1.06 and above range there is a small variation... very small but different never the less.


At the end of the brew day I wait with baited breath, for the final gravity of a couple hours work. From there I am thrilled that all the preparation paid off, ecstatic for a good days effort or disappointed that something went awire.


So who do you trust.. A Hydrometer or Refractometer?

photo (2).jpg
 
how far off are they, could be that the refractometer is adjusted for temp and the hydrometer is reading the correct gravity at the current temp and the refrac is adjusting
 
Refractometer for OG and Refractometer for FG. I think it was Yopper that told me that, a Refractometer can read different when used for FG because of the alcohol.
 
I like my digital refractometer.

OP, what kind of refractometer is that? I've never seen that one before.
 
how far off are they, could be that the refractometer is adjusted for temp and the hydrometer is reading the correct gravity at the current temp and the refrac is adjusting

The difference is about 0.002-0.004.. not huge. I have based all my calculations off the refractometer since using those numbers puts my efficiencies between 80-83%.


I like my digital refractometer.

OP, what kind of refractometer is that? I've never seen that one before.

It is a Toko refractometer, all stainless and weighs in at 350 grams. If you see one of these pop up used, from a quality standpoint these are very nice.
 
If you are sure they are both calibrated perfectly, then I would take the average between the two measurements (for OG). The last digit is a 'guess' digit anyway. Obviously for the FG I would solely use the hydrometer. You should borrow a friend's hydrometer or refractometer and see how they square up.

side note: I used to have that hydrometer in your picture and it was way off compared to my other ones. That could have just been a problem with that one hydrometer..but who knows?
 
The difference is about 0.002-0.004.. not huge. I have based all my calculations off the refractometer since using those numbers puts my efficiencies between 80-83%.




It is a Toko refractometer, all stainless and weighs in at 350 grams. If you see one of these pop up used, from a quality standpoint these are very nice.

Sounds like it could be a difference in temperature to me. What temps are you taking the readings at??
 
IMO/IME, a quality refractometer will beat any hydrometer.

The difference you're seeing could be the difference in the paper on the hydrometer where the graduations are printed. I've long since set the hydrometer aside and just use the quality refractometers for my readings.
 
I used to use my hydrometer and refractometer when brewing. Now I just use the refractometer because it has been accurate since day one.
I will still use the hydrometer when taking gravity samples. Getting enough to float the hydrometer ensures I get enough of a sample for tasting purposes.
 
Hydrometer.

A hydrometer measures density directly. "Gravity" is density with respect to water. (note: I had one that was way off once, so do a 2-point cal).

Using the refractometer to measure gravity is just a loose trick based on refraction, which is the angle light bounces off a material (i.e., sucrose in water). It's a trick that requires calibration and also some assumptions about the liquid. I have one and I know they work OK for OG but not for FG. And, even the OG is suspect across different types of beers.
 
All things I've read say that a refractometer goes zany in the presence of alcohol. Being that I am making beer (nothing NA), I choose a hydrometer. I don't want to have to run my tool's measurements through some algorithm just to take a gravity reading.

To each his own, though.
 
All things I've read say that a refractometer goes zany in the presence of alcohol. Being that I am making beer (nothing NA), I choose a hydrometer. I don't want to have to run my tool's measurements through some algorithm just to take a gravity reading.

To each his own, though.

I'd rather not have to worry about any bubbles coming out of suspension in the hydrometer sample tossing the numbers way off. Or having foam on top of the sample obscure the reading. Besides, the amount of sample needed for a refractometer is so tiny compared with a hydrometer it's almost comical.

If you have BeerSmith 2.1.x, or another good brewing application, it has the algorithms built in for use. You just need to learn how to use them (takes all of a couple of minutes to figure it out, then a few seconds to get the FG number).

BTW, with a refractometer, I can save a sample in a 4 dram vial (that's about 1/2oz) in the fridge for later. There's been more than a few times where I'm taking FG and OG readings at the same time. :eek: Not a viable option if you're using a hydrometer.

As for passedpawn... IF you have a quality refractometer, calibration isn't needed all that often. It's not possible to calibrate a hydrometer. Plus, try to take a reading with mash runnings with your hydrometer (within a minute of pulling the sample). You can't do it, at least not with any degree of accuracy. No matter how you think the high temperature offset should be, chances are you're way off.

Think what you like, but a quality refractometer is as good (if not better) than any hydrometer out there. As with most things, you DO need to know how to use it properly though. :eek: :D
 
I trust my hydrometer. I use my refrac during the middle of the brew day to make sure that I'm in the right ball park. It's often a point or two off (both are calibrated at 1.000 with DI water) when measuring OGs over 1.050, which is where most of my beers fall.

It's not hard to take hydro readings, so I don't mind.
 
As for passedpawn... IF you have a quality refractometer, calibration isn't needed all that often. It's not possible to calibrate a hydrometer. Plus, try to take a reading with mash runnings with your hydrometer (within a minute of pulling the sample). You can't do it, at least not with any degree of accuracy. No matter how you think the high temperature offset should be, chances are you're way off.

Think what you like, but a quality refractometer is as good (if not better) than any hydrometer out there. As with most things, you DO need to know how to use it properly though. :eek: :D

No, sorry Goldie, but you're wrong some of that. I will agree that a refractometer is great for doing measurements during the boil (that's the only time I use one). Also, when I said "cal" your hydrometer, I meant to check it for accuracy. You're right, if it isn't accurate, it's a tosser.

Refactometers are calibrated for a sucrose solution. Beer is a combination of different types of sugars, including sucrose, maltiose, dextrose, and maybe others. The rub is that different beers contain different ratios of these sugars. So, you could calibrate your refractometer to one type of beer, say a pilsner, and it would work great for that, but then make a porter and it's way off again.

Further, the correction formulas in software that attempt to correct for FG, when alcohol is present, are not accurate as well. Sean Terrill has spent a ton of time working this out. You can form your own opinion by listening to him on the following podcast, and checking out his invaluable studies on this subject. I'll post the links below, as well as his online calculator. In his words, "[The current correction algorithm] is also noticeably less precise than even the relatively poor “triple scale” hydrometers used by most home brewers".

When you see the calculator, you'll also notice there is a "Wort Correction Factor" that you need to enter. This must be empirically determined for each different recipe. If you brew the same exact beer often, you could figure this out and expect great FG accuracy from the refractometer. If you brew different beers, you'll never have this number.

Take a look at the stuff below and you be the judge. His blog is full of great discussion with research.

Sean Terrill Discussion on Refractometer FG

Basic Brewing Episode with Sean Terrill

Sean Terrill Refractometer Calculator
 
I guess I haven't yet encountered a quality refractometer. I have long used one for my reef aquarium for salinity measurements so have quite a bit of experience. However, I have tried two different wort refractometers and despite my calibrations through Beersmith neither has shown a comfortable degree of consistency. I would love to be able to trust one due to the simplicity of it but so far I can't.
 
I took both hydrometer and refractometer readings of OG and FG from several batches. For the refractometer FG calculation I have been using this page: http://onebeer.net/refractometer.shtml

In my personal tests I found that my refractometer results always matched the hydrometer results. So, I only use my refractometer now.

I am sure that there may be scenarios where the results may be skewed but I guess I haven't hit them yet.
 
Just bought my first refractometer a few days ago and I'm stoked to use it. I have always had concern about the tiny sample size used with them though. Is a gravity reading with only a couple drops of wort truly indicative of the entire batch? What if you happen to take a couple drops from an area with more or less sugar concentration than the rest? A hydrometer reading uses what, 1000x the sample size? It seems to me that this would be more accurate in measuring the entire batch.
 
I just got my refracto recently but haven't had a chance to use it during brewing yet. I did try it out on two batches I had finishing up and was pleased to see it match up on the nose with the hydro for FG. This was after using the correction tool in Beersmith.

My plan is to use the refracto during the mash the most. I'm excited about the idea of being able to take a lot of samples using just a few drops to see the progress of the mash and not having to wait for a hydro sample to cool to get to a point where the correction is at least close to working. At least for awhile I plan to do samples on both for the OG going in and the FG and really see what happens. If the refracto proves to be reliable though I'll probably ditch the hydro.

Interesting to consider different styles of beer behaving differently though. I can definitely see that as the sugar solution changes. Fortunately, I think most of my profiles probably come out similar enough that it would be pretty minor differences. Something to consider for sure if I ever start swinging around in dramatically different grain profiles.
 
No, sorry Goldie, but you're wrong some of that. I will agree that a refractometer is great for doing measurements during the boil (that's the only time I use one). Also, when I said "cal" your hydrometer, I meant to check it for accuracy. You're right, if it isn't accurate, it's a tosser.

Refactometers are calibrated for a sucrose solution. Beer is a combination of different types of sugars, including sucrose, maltiose, dextrose, and maybe others. The rub is that different beers contain different ratios of these sugars. So, you could calibrate your refractometer to one type of beer, say a pilsner, and it would work great for that, but then make a porter and it's way off again.

Further, the correction formulas in software that attempt to correct for FG, when alcohol is present, are not accurate as well. Sean Terrill has spent a ton of time working this out. You can form your own opinion by listening to him on the following podcast, and checking out his invaluable studies on this subject. I'll post the links below, as well as his online calculator. In his words, "[The current correction algorithm] is also noticeably less precise than even the relatively poor “triple scale” hydrometers used by most home brewers".

When you see the calculator, you'll also notice there is a "Wort Correction Factor" that you need to enter. This must be empirically determined for each different recipe. If you brew the same exact beer often, you could figure this out and expect great FG accuracy from the refractometer. If you brew different beers, you'll never have this number.

Take a look at the stuff below and you be the judge. His blog is full of great discussion with research.

Sean Terrill Discussion on Refractometer FG

Basic Brewing Episode with Sean Terrill

Sean Terrill Refractometer Calculator

This may be what I am seeing, once you hit a certain point the readings no longer correlate with wort and there is a separation. It was most obvious in my latest brew of Westy 12 with a OG of 1.094.

I did a step series today using simple table sugar at certain ratios and they matched perfectly.

Now, will understanding this ruin my brew day now... no. This isn't rocket science, but it is important to understand the various measurement of uncertainty in our testing systems. Great that we rediscover the wheel ever now and again.
 
Hey guys - I happened on this thread and I have a used ToKo refractometer as mentioned in previously. It is in great shape and I would love to get it to someone who can use it properly. I have no use for it. It was my fathers.

PM me if interested please.
 
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