Can my refractometer replace hydrometer?

[Saint-Thomas]

So I have been playing around with my new brix refractometer and reading up on the archives here about how to use it. I calibrated it to distilled water and next step is to calibrate it to some sugar concentration. The only accurate measuring devices I have area triple beam scale and a digital thermometer, so I guess I need to convert volume to weight for the water part.

I also took some samples of finished beer and was shocked to discover how high the numbers seemed. After a bit of research I discovered that alcohol affects the reading? Well crap! I had hoped to ditch the dang hydrometer altogether as I get frustrated trying to read it, especially in the finished beer when there may still be disolved gas interfering with the reading.

So, how do you use a refractometer to get your final gravity reading? I know there's a formula, but I'm more interested in a quick fix here. Hoe would you plug in your brix reading into Promash, for example? Or do I still need to take a hydrometer reading after all?

[Jared]

I too Have been considering purchasing a refractometer. From what a friend says in my homebrew club A hydrometer should be used in conjunction with the tool. All the brewerys I've ever been to there is always a sink testing area with a bunch of hydrometers ready to take readings. So if the pros use 'm' I will too. But both would be nice. For instance taking readings pre-boil and first runnings and checking the gravity whilst fly sparging to know when to stop collecting. ect.. These mesurements are difficult to do with a hydrometer because of the temps.

Will I buy a refractometer? probably but not before I purchase a nice profesional hydrometer\glass cylinder which can get pretty pricey.

[Saint-Thomas]

Checking readings on the fly during wort production is exactly why I got my refractometer. I got tired of running back to the computer to check for temperature correction. I did hope that I could get away with not using the hydrometer though. To take readings post-fermentation is such a PITA. You gotta get all your sanitizing stuff out, then sanitize your thief and whatever else may come in contact. If you end up having to take several readings, your finished output is significantly diminished.

[corkybstewart]

Promash has a feature that does it for you, but I like using the hydrometer during fermentation. It lets me taste the beer as it progresses. Licking that drop off the refractometer just doesn't do it for me.

[Saint-Thomas]

Corky, I agree that the benefit to checking gravity is tasting, which is an important empirical test. After all, we are doing it to make something that tastes good, are we not?

How do you use ProMash to convert final reading to a gravity (taking alcohol into account)? If I just put in the plato number, then the gravity is wrong. (ie. a finished Belgian strong ale I just tested, reading 7.8 brix would equal 1.030 using a simple conversion, which it is not.)

[corkybstewart]

I've never used it before so I have no idea. I've seen someone explain it before but since I use the hydrometer I never worried about it.

[paulcgi]

I had always heard and read that brix refractometers were useless in beer, except for certain things.. from the St. Pats website:

"Brix Refractometers measure the sugar content of grapes. They cannot measure the sugar content once fermentation has begun due to the presence of alcohol. A hydrometer is used once fermentation has begun.
Refractometers are never accurate in brewing because malt sugars are not the same as grape sugars. However, refractometers are used by brewers as indicators of 1)extent of conversion during the mash and 2) end point of sparging. The 0-32 Brix refractometer is the best choice for the former and the 0-10 Brix for the latter. Although inaccurate, the readings provide a consistent and reliable indication of the relative amount of sugars. Once fermentation has begun, a refractometer has no use in brewing. "

I still also would like to get one for numbers 1 and 2 above tho

[BrewDog]

If you know the OG of the wort, and you measure the FG of the beer, you can use the calculator to figure out the actual finishing gravity and hence the alcohol content.

I disagree with the St. Pats statement fully. A refractometer CAN be used to replace your hydrometer. It only requires a simple adjustment. In another thread, I posted that formula. In Promash (and I assume other brewing software) it is a simple matter of entering your OG and the measured FG.

The formula is the key. They came up with the formula by experimentation and curve fitting thousands of actual samples that were measured both by refractometer and hydrometer. There's nothing wrong with that. How do you think engineers figured out that an I-beam of size X is capable of holding Y pounds? They took thousands of sample measurements and curve fitted a formula to the observations.


Here's how you do it in Promash. Load your session and push the Fermentation button at the bottom left.

In the bottom row of that screen you will see a little picture of a refractometer and then 2 radio buttons where you select whether the reading is by hydrometer or by refractometer. Set the one that says refractometer. Ignore the little picture of the refractometer in the bottom row.

You should have already entered the OG value. If you haven't, you do that now. If not, it is pre-populated with the expected OG from your recipe.

Now, it's time to enter the FG value. Click on the little refractometer picture to the RIGHT of the FG entry field. This pops up another dialog box.

The first field lets you type in your reading. Hit OK and it will fill in the FG for you on the fermentation screen.

That's it. You are done. It has done all the calculations for you, and you can see what your FG and alcohol content are.

HTH-

[Saint-Thomas]

Thanks BrewDog! I think this is what I'm looking for. It was your post in another thread which had the formulae that got me thinking about this. I knew there had to be a way to do it within the brewing software programs.

One question, I *think* I followed your example correctly and noticed that by putting in the brix I got a different ABV number than by using SG. However, the gravity field did not change. When I put in 8 brix, I get 1.032 specific gravity and a ABV that looks about right for this beer. But if I put in the gravity, then the ABV is low.

I'll keep playing around with it. I'm doing a porter today and taking thorough and copious notes on every piece of data I can think of. So far the refractometer has been quite useful in the extraction process and all my numbers were close to what Promash predicts.

[paulcgi]

sweet.. thanks brewdog.

but then again.. damn.. SWMBO's not gonna be happy that I'm going to buy MORE beer stuff

[HogieWan]

Originally posted by corkybstewart
Promash has a feature that does it for you, but I like using the hydrometer during fermentation. It lets me taste the beer as it progresses. Licking that drop off the refractometer just doesn't do it for me.

I usually pour some for the side port into a small glass and let it settle for a bit. I then put a few drops on the refractometer, then take a sip of the rest of the sample. Best of both worlds.