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Hydrometer v/s refractometer

When I started brewing, I purchased a hydrometer to measure my brews OG and FG. The hydrometer has worked well, however, I do find it difficult to read and I never cared for how much wort I wasted when taking measurements. Well, I got a 25 dollar gift card for Christmas and decided to buy a refractometer. The first time I used it was to check the FG of one of my brews. The reading was way off. I had no idea at that time that a refractometer was unreliable for checking FG. With that said, what is the preferred tool of long time brewers for measuring OG and FG? Is there a way to take precise measurements of my FG since the refractometer will not do the job? Should I quit worrying so much about my FG, just give it time, and go drink a beer?

I don’t own a refractometer so can’t attest to it’s accuracy but this page supposedly will correctly compensate for alcohol present in your FG reading using a refractometer:

http://seanterrill.com/2012/01/06/refra ... alculator/

Its not that its unreliable, it just needs to be adjusted when it is reading a solution with alcohol in it. Still works great.

I will say, I rarely check FG these days. I ramp up my fermentation temp on just about all beers (ales and lagers), and I can usually taste when they are done. That being said, I typically work with 2-3 yeasts at most, and if I am brewing something with a yeast I am not used to (such as a lager yeast, san fran lager, or some belgian strains for example), I will definitely take a few gravity readings after I THINK fermentation has completed.

I always check with a refractometer. Broke my hydro a few years back and never bought a new one.

I don’t even remember where my hydrometer is anymore. A refractometer will never be as accurate for FG as a hydrometer, but does it really matter that much? I use the corrected refractometer value to verify FG is not changing over a few days, and that pretty much tells me everything I need to know, that the fermentation has not stalled and is stable.

Thx!

I learned a couple of years ago that an automatic temperature correcting (ATC) refractometer does NOT correct for very hot wort. I now cool my wort by dipping a tiny sample with a thick-bottom glass, swirling the sample, and pouring the sample into a second glass for about one minute before dripping it onto the sample glass.

If it doesn’t correct for hot wort, it seems reasonable that it doesn’t correct for cold beer either.

Regardless of the wort/beer temp, you must correct for the presence of alcohol in fermenting/fermented beer.

Finally, Denny recently explained that an ATC refractometer corrects for the temperature of the refractometer itself, not the for the temperature of the wort!

So, get your wort to somewhere in the neighborhood of the refractometer and correct for any alcohol present and your refractometer will tell you the truth. They’re great tools because they require a tiny sample and give a quick reading.

P.S. Do as I say not as I do: read the directions!

[quote=“Old_Dawg”]I learned a couple of years ago that an automatic temperature correcting (ATC) refractometer does NOT correct for very hot wort. I now cool my wort by dipping a tiny sample with a thick-bottom glass, swirling the sample, and pouring the sample into a second glass for about one minute before dripping it onto the sample glass.

If it doesn’t correct for hot wort, it seems reasonable that it doesn’t correct for cold beer either.

Regardless of the wort/beer temp, you must correct for the presence of alcohol in fermenting/fermented beer.

Finally, Denny recently explained that an ATC refractometer corrects for the temperature of the refractometer itself, not the for the temperature of the wort!

So, get your wort to somewhere in the neighborhood of the refractometer and correct for any alcohol present and your refractometer will tell you the truth. They’re great tools because they require a tiny sample and give a quick reading.

P.S. Do as I say not as I do: read the directions![/quote]

Those are VERY good points. Also, when measuring hot wort, I’ve started pouring a sample on the prism and closing the cover very quickly, since it rapidly evaporates and you’ll get a much higher reading. Let it cool with the lid closed and take your measurement. I figured that out the hard way.

[quote=“porkchop”][quote=“Old_Dawg”]I learned a couple of years ago that an automatic temperature correcting (ATC) refractometer does NOT correct for very hot wort. I now cool my wort by dipping a tiny sample with a thick-bottom glass, swirling the sample, and pouring the sample into a second glass for about one minute before dripping it onto the sample glass.

If it doesn’t correct for hot wort, it seems reasonable that it doesn’t correct for cold beer either.

Regardless of the wort/beer temp, you must correct for the presence of alcohol in fermenting/fermented beer.

Finally, Denny recently explained that an ATC refractometer corrects for the temperature of the refractometer itself, not the for the temperature of the wort!

So, get your wort to somewhere in the neighborhood of the refractometer and correct for any alcohol present and your refractometer will tell you the truth. They’re great tools because they require a tiny sample and give a quick reading.

P.S. Do as I say not as I do: read the directions![/quote]

Those are VERY good points. Also, when measuring hot wort, I’ve started pouring a sample on the prism and closing the cover very quickly, since it rapidly evaporates and you’ll get a much higher reading. Let it cool with the lid closed and take your measurement. I figured that out the hard way.[/quote]

Porkchop,
I’ve tried that and have gotten inconsistent readings. I’ve had much better results cooling a VERY small sample in a heavy glass, pouring that into a second glass to get the wort to the same temperature as the refractometer, then dripping the sample onto the glass.

I have both. Although I can say the refractometer is quick and uses less sample, I often find my self using the good oil’ hydrometer. It to is pretty quick, accurate, doesn’t need adjusted for alcohol, and is RELIABLE. I’ve received different readings from the same liquid when using my refractometer. Here’s a good read:

http://www.brewersfriend.com/2013/04/24 ... e-brewing/

[quote=“Old_Dawg”]

Porkchop,
I’ve tried that and have gotten inconsistent readings. I’ve had much better results cooling a VERY small sample in a heavy glass, pouring that into a second glass to get the wort to the same temperature as the refractometer, then dripping the sample onto the glass.[/quote]

I’m going to start doing it your way because it sounds like a really good idea. I love the convenience of a refractometer, but I’ll admit they’re touchy. Anything to provide a more reliable measurement is a good thing. Thanks for the feedback!

I use both. A refractometer on brew day and a lab grade 0.980 - 1.020 hydrometer to measure FG.

I have an optical refractometer, digital refractometer, standard hydrometer and precision hydrometers. I use the precision hydrometers for everything except measuring OG for starter wort. Could never get my refracometers to agree with each other, let alone the precision hydrometers. I frickin love the precision hydros! Worth every penny.

Agreed! They are so easy to read and accurate. As mentioned above I’ve never owned a refractometer because I don’t like using things that are finicky or “accurate enough”.

I see people talking about measuring the OG of their wort when its hot. I have always waited till it’s cooled before taking my measurements. Is this the wrong way to accomplish this? Also, I didn’t know that refractometers were considered “accurate enough”. Hmmmm… sounds like hydros are the way to go for my personality.

My refractometer has always agreed with my hydrometer when measuring wort. It’s also pretty close with fermented beer, but that depends on the style (more fermentable styles are closer, while styles with lots of unfermentable sugars tend to be off.)

It’s also a good idea to calibrate your measuring devices:

http://byo.com/stories/issue/item/411-calibrate-your-hydrometer-and-fermenter-techniques

Use the sugar solution to calibrate your refractometer as well if you have one.

I’m pretty anal about taking pre-boil, original and final gravity readings. I measure pre-boil gravity hot. I use the beersmith app on my phone to calculate the actual gravity (compensating for temp). I’ve found it’s accurate.

Since you have to chill the wort to pitch, I don’t see any reason to take that reading hot.

I check first and second runnings hot and preboil gravity, and then check the wort after the boil time has elapsed, but before I kill the flame. A fraction of a milliliter will cool pretty quickly on the refractometer glass. I also take a confirmation reading before pitching, and I’ve never seen a discrepancy between final post-boil and pre-pitching readings.

I check gravity during the brew day with my refractometer but at the end of the boil, I use the hydrometer for getting an accurate OG. Then a couple weeks later, I check FG by putting the sanitized hydrometer directly into my fermenters. I check it again at kegging time the same way.

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