Best way to calibrate my refractometer (and hydrometer?)

[eddiewould]

Hey guys,

I like to use my refractometer during my sparge to keep track of where my runnings are at. However I'm concerned my readings might not be accurate (they seem to be inconsistent with my hydrometer for cooled, unfermented wort).

Here are the specs for my refractometer: (Hopefully the link works):
http://www.trademe.co.nz/Browse/Listing.aspx?id=450208419

It's supposedly designed for homebrewing and it's got markings for Brix as well as "specific gravity scale for unfermented wort". It's also got ATC so I've just been pippetting a few drops of my runnings (70c or so), giving it 30sec to stabilize and then taking a reading.

The specs do say "ATC for 10c to 30c" but small drops of wort are unlikely to stay at 70c for long right? I've also tried running the pippette (full of wort) under the cold tap for a few seconds before dispensing the wort and taking a reading - it didn't seem to make any difference, so I'm not convinced that temperature is the issue. (Note, I only take hydrometer readings when wort is room temperature i.e. 15-20c, and I adjust the hydrometer readings for temperature).

The refractometer came with a tool for calibrating it, but I've never bothered (I guess I'm partly scared of making things worse rather than better).

Assuming I've got some accurate scales, is there a way I can weigh out some DME (or table sugar?), add to a known quantity of water (so that I know what the gravity should be) and calibrate both my hydrometer and refractometer in one go?

If I calibrate my refractometer using light DME (say), will it be accurate for measuring the gravity of a stout?


Cheers,
Eddie

 

[Pratzie]

Get distilled water and calibrate it to zero to start with. That and ur hydrometer and see how accurate they are.

 

[Hex23]

I think you'll like this thread. I learned a lot there. https://www.homebrewtalk.com/f36/refractometer-question-362437/

Edit: Posts 8, 11, and 38 are particularly relevant to the issue you are noticing.

 

[cody6173]

Sorry, I'm not going to be of any help but I'd like to see where this goes. I have the same problem with my hydrometer, to the point that I rarely use it anymore. I get very inconsistent readings during brewing. I even gone so far as to pipette some wort into a glass, let it cool, check the gravity and then take another reading from the same sample and its usually off by at least 10 gravity points if not more. Right before I pitch my yeast I usually take a refractometer reading and a hydrometer reading and they're usually pretty far off from one another.

 

[Pratzie]

https://www.homebrewtalk.com/f39/refractometer-413355/index5.html

Read Post 42 to learn how to configure it at higher gravitys when the accuracy gets a little screwy.

 

[mtnagel]

Thanks for mentioning my post. Also check out my post where I posted the results of measured sugar solutions with my refractometer and how they were off from expected based on the amount of sugar and water I was using, but I attribute some of the error to my cheap scale.

Also check that your brix scale actually matches up with your SG scale. Here's the one I bought and my SG scale is off, so now I only use it for brix and then convert using an online calculator to get my SG. Defeats the purpose of getting the dual scale one, but oh well. I should have figured that out before I bought it.

To check yours, make sure that 30 brix matches up with 1.129. Use this calculator to convert between brix and SG. You can see from the picture on Amazon that mine would read about 1.117 so that's why I only use the brix now. Here's the picture:

 

[Hex23]

Sorry, I'm not going to be of any help but I'd like to see where this goes. I have the same problem with my hydrometer

Did you mean refractometer? It's harder to believe you'd have measurement problems with a hydrometer. Other than the occasional 2-3 pt mis-calibration I've seen with distilled water, they are generally pretty reliable. I admit I've seen funny things happen with temperature correction when at mash temps.

I even gone so far as to pipette some wort into a glass, let it cool, check the gravity and then take another reading from the same sample and its usually off by at least 10 gravity points if not more.

Are you talking about two successive hydrometer measurements here?

 

[Pratzie]

ur welcome. its helped me out with my own and it sounds like he could use it!

 

[mtnagel]

One more thing to note that I witnessed when I brewed this weekend. I was doing BIAB. My method is to lift the bag and put a grill grate on top the pot and let the bag drain on that. When I was almost done draining, but before I moved the bag, I just stuck my pipet in through the grill grate and grabbed a few drops. The gravity was low, like 5 brix too low. After moving my bag and grate and bringing to a boil, I gave a it a decent stir and took the reading again and it was almost exactly on target.

So the lesson learned is to stir before taking a gravity reading.

 

[cody6173]

Did you mean refractometer? It's harder to believe you'd have measurement problems with a hydrometer. Other than the occasional 2-3 pt mis-calibration I've seen with distilled water, they are generally pretty reliable. I admit I've seen funny things happen with temperature correction when at mash temps.

Are you talking about two successive hydrometer measurements here?

My bad. I meant to say with my refractometer is the inconsistent one. My hydrometer on the other hand is like sex panther cologne. 60% of the time it works all the time.

 

[TAK]

Subscribed for future reference. I have a refractometer in the mail right now heading my way, and I'm sure I'm going to reference back to this thread soon. I'm also quite curios to see how well post-fermentation adjustments go.

 

[hiphops]

I have both a refractometer and a hydrometer. I've given up on the refractometer for a number of reasons. First, it nearly impossible to read the measurements. The lines are so close together, making it nearly impossible to distinguish between say a reading of 1.080 and 1.085. Second, its wildly inaccurate. I've had wildly different readings in gravity from the same same wort. I don't know why: perhaps it has something to do with the fact that you are sampling such a small portion of the wort that any portion will be wildly unrepresentative of the wort as the whole. To compensate for all these contradictions and inaccuracies, I use to simply take 3 different measurements and average it out and use that as my official gravity reading. Now, however, I use the hydrometer. Although its not as fancy, it seems to work better.

My advice? Junk the refractometer.

 

[mtnagel]

Not trying to convince you, because I really don't care, but..

I have both a refractometer and a hydrometer. I've given up on the refractometer for a number of reasons. First, it nearly impossible to read the measurements. The lines are so close together, making it nearly impossible to distinguish between say a reading of 1.080 and 1.085.

In the picture above you can't tell the difference between 1.080 and 1.085? Maybe you need to get your eyes checked

I do agree that I can't quite tell a difference of 0.001, but 0.005? I'm pretty sure I can tell that. I have noticed that sometimes the line is fuzzier than other times. If my target is 1.065 and I'm +/- 0.002, I'm okay with that. It's not like we are selling this stuff that we need to be super accurate.

Second, its wildly inaccurate. I've had wildly different readings in gravity from the same same wort. I don't know why: perhaps it has something to do with the fact that you are sampling such a small portion of the wort that any portion will be wildly unrepresentative of the wort as the whole. To compensate for all these contradictions and inaccuracies, I use to simply take 3 different measurements and average it out and use that as my official gravity reading. Now, however, I use the hydrometer. Although its not as fancy, it seems to work better.

Did you see my advice above, "So the lesson learned is to stir before taking a gravity reading." I wonder if that's your issue. You need to get a homogeneous sample or it will be inaccurate on subsequent readings.

My advice? Junk the refractometer.

That's cool if you don't want to use it, but I love mine and how you don't have to waste so much sample. I love mine now that I've gotten used to its quirks.

 

[brewkinger]

I have been working on fine tuning my refractometer usage and this might prove helpful:
https://www.homebrewtalk.com/f36/refractometer-question-362437/index11.html#post5292958

 

[Gameface]

Mine says 23brix = 1.088, but mines been dead on accurate. During the brew day I take refractometer reading and then I snag some beer while I'm transferring to the fermentor for a hydro sample. They always match, at least within 1-2 points. I checked the cal on my refrac and after about a year and a half of use I haven't adjusted it except when it was new out of the box. It's been dead on.

You guys started freaking me out with all this stuff but then I RDWHAHB'd and realized I'm good to go, so no need to panic.

Interesting stuff, though. I learned more than a couple things about how my refractometer works.

 

[mtnagel]

Can you post a link to which one you have?

 

[eddiewould]

This page http://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/ looks really helpful. I might give this a go.

 

[Grossy]

Yep I gave up on my refractometer too.

Take one reading get one result, take another get another result.

So I went to a copper hydrometer vessel and ice bath. Now I can accurately measure the hot wort in 60 seconds.

I posted this build here:

Copper Graduated Cylinder, hot wort, fast read

 

[eddiewould]

These are the readings from my latest brew day:

At sparging start:
Hydrometer: 1.046
Temperature: 50c
Adjusted hydrometer reading: 1.055
Refractometer reading: 1.057

Refractometer correction factor = 1.03636363636364

At start of boil
Hydrometer: 1.030
Temperature: 47c
Adjusted hydrometer reading: 1.038
Refractometer reading: 1.035

Refractometer correction factor: 0.92105263157895 ? eh

At pitching
Hydrometer: 1.050
Temperature: 19c
Adjusted hydrometer reading: 1.050
Refractometer reading: 1.047

Refractometer correction factor: 0.94


What correction factor should I use when taking readings from my refractometer?

 

[eddiewould]

These are the readings from my latest brew day:

At sparging start:
Hydrometer: 1.046
Temperature: 50c
Adjusted hydrometer reading: 1.055
Refractometer reading: 1.057

Refractometer correction factor = 1.03636363636364

At start of boil
Hydrometer: 1.030
Temperature: 47c
Adjusted hydrometer reading: 1.038
Refractometer reading: 1.035

Refractometer correction factor: 0.92105263157895 ? eh

At pitching
Hydrometer: 1.050
Temperature: 19c
Adjusted hydrometer reading: 1.050
Refractometer reading: 1.047

Refractometer correction factor: 0.94


What correction factor should I use when taking readings from my refractometer?

I punched the numbers into this spreadsheet: http://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/ and it gave me three correction factors - 0.88323, 0.90239 & 0.94449 with an average of 0.91. So that sounds more reasonable.

 

[fartinmartin]

My refractometer agrees with my hydrometer ! I bought it to give me the SG of wort and it does exactly that. Once the yeast is pitched I put the refractometer away as at that point the wort isnt wort any more it is beer in process, the refractometer is not scaled for that!
I calibrated with tap water and condensed water from steam and melted ice from the freezer all read the same.

 

[mtnagel]

You might want to check the higher end with sugar solutions. Here's how I did mine.

 

[Yooper]

These are the readings from my latest brew day:

At sparging start:
Hydrometer: 1.046
Temperature: 50c
Adjusted hydrometer reading: 1.055
Refractometer reading: 1.057

Refractometer correction factor = 1.03636363636364

At start of boil
Hydrometer: 1.030
Temperature: 47c
Adjusted hydrometer reading: 1.038
Refractometer reading: 1.035

Refractometer correction factor: 0.92105263157895 ? eh

At pitching
Hydrometer: 1.050
Temperature: 19c
Adjusted hydrometer reading: 1.050
Refractometer reading: 1.047

Refractometer correction factor: 0.94


What correction factor should I use when taking readings from my refractometer?

The problem with ALL of those readings (except the last one) is that the readings were taken too hot for an accurate hydrometer reading. Even with temperature correction software, a hydrometer reading is notoriously inaccurate above about 90 degrees.

The sample should be cooled to 90 degrees or less, then temperature corrections applied and then it should be accurate. Hydrometer are great- but not with hot readings.

 

[homebrewer_99]

One thing I've noticed is that you will get inaccurate readings if you don't wash the old sample off first.

Just something to remember.

 

[royco]

I think you'll like this thread. I learned a lot there. https://www.homebrewtalk.com/f36/refractometer-question-362437/

Edit: Posts 8, 11, and 38 are particularly relevant to the issue you are noticing.

This thread is quite old but I hope it is still "alive". I recently bought a refractometer with ATC, Brix and SG scales. Calibrated to zero with distilled water. Checked gravity of a Pilsener 2 weeks into primary and got 1030 SG or around 7.6 Brix. A week later after all visible signs of fermentation had ceased I took another reading: still 1030. After recovering from the ensuing mild seizure I decided to check with my hydrometer and got a reading of 1005!
After extensive research it seems these toys need further calibrating in the working environment, but this variation seems absurd. May as well stick with the hydrometer.

 

[Carlscan26]

This thread is quite old but I hope it is still "alive". I recently bought a refractometer with ATC, Brix and SG scales. Calibrated to zero with distilled water. Checked gravity of a Pilsener 2 weeks into primary and got 1030 SG or around 7.6 Brix. A week later after all visible signs of fermentation had ceased I took another reading: still 1030. After recovering from the ensuing mild seizure I decided to check with my hydrometer and got a reading of 1005! After extensive research it seems these toys need further calibrating in the working environment, but this variation seems absurd. May as well stick with the hydrometer.

You can't use a refractometer with using a correction calculator once there's alcohol in the solution.

 

[sjskeels]

You have to correct for fermentation. You can find calculators for this in brewing software or online.

 

[Yooper]

This page http://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/ looks really helpful. I might give this a go.

I really like the info on brewer's friend! I'm going to experiment with this: http://www.brewersfriend.com/refractometer-calculator/

This thread is quite old but I hope it is still "alive". I recently bought a refractometer with ATC, Brix and SG scales. Calibrated to zero with distilled water. Checked gravity of a Pilsener 2 weeks into primary and got 1030 SG or around 7.6 Brix. A week later after all visible signs of fermentation had ceased I took another reading: still 1030. After recovering from the ensuing mild seizure I decided to check with my hydrometer and got a reading of 1005!
After extensive research it seems these toys need further calibrating in the working environment, but this variation seems absurd. May as well stick with the hydrometer.

Yes, stick with the hydrometer AFTER fermentation has started as a refractometer "reads" sugar solution by the light refraction. The readings are skewed once alcohol is in the solution, and are not correct.

There are some software corrections that can be done, but for my brewing I use a hydrometer once, when fermentation is done and just before packaging. Preboil and post boil readings are done via refractometer.

 

[TAK]

Details here about using a refractometer and hydrometer in combination:
http://woodlandbrew.blogspot.com/2013/02/abv-without-og.html

This was posted on another thread. Hydrometers are the only way to accurately read FG, but this article outlines a way to actually leverage the attribute of a refractometer that makes it inaccurate for FG readings to deduce ABV. I've been comparing the ABV from this method to ABV calculated from hydrometer OG/FG on several of my batches, and the two figures are always within a few points of each other.

 

[stevedasleeve]

I've used hydrometers for several years, all were off by 2 or 3 points. I got tired of sanitizing and cooling and spilling and ultimately breaking and buying a new one so I got a decent refractometer last year and use it exclusively.