Refractometer and using during fermentation

[harbngr]

I started all grain brewing, with 5 gal batches. I know about the issues during fermentation using a refractometer.

my question is this, and looking to see if my reasoning is ok.

I'm planning on just taking a small sample of wort during fermentation daily and checking progress with the refract. With the purpose of monitoring when fermentation is done. My theory is that it should be finished if I get the same reading a couple of days in a row.

For the F.G. I do use a hydrometer. I just really don't want to waste that much beer to get accurate numbers with a hydro.

So sound idea or not?

 

[Vale71]

In principle yes, in practice if fermentation tapers off quite slowly at the end two days might not be enough, also depending on how accurate your refractometer readings are. But that's of course a general issue and not specifically related to the use of a refractometer.

 

[day_trippr]

fwiw, I recently re-confirmed my "converted" refractometer readings of fermenting/fermented wort are within eyeball error of my hydro. I mean, depending on which side of the lines I take as the readings (for both tools), they're either dead nuts in agreement or a half-point different...

Cheers!

 

[LittleRiver]

... it should be finished if I get the same reading a couple of days in a row... I just really don't want to waste that much beer to get accurate numbers with a hydro. So sound idea or not?

Using a refractometer to detect the absence of change is a totally sound idea.

 

[dmtaylor]

Petr Novotny's refractometer conversion calculator was designed for measurement of SG during the course of fermentation. Brewer's Friend uses his calculation, available at link below. Your method should work pretty well I think, AND you can even use this equation to get an approximate SG within a point or two.

https://www.brewersfriend.com/refractometer-calculator

 

[harbngr]

Thanks for chiming in guys, appreciate it .

 

[kh54s10]

I would make things easier on yourself. Wait until all signs of fermentation have stopped and the krausen has fallen, add another couple of days then take your first gravity reading. Unless you are researching the fermentation process there is no need for more than 2 gravity readings. In fact I ferment for 2 weeks, take one gravity reading, and if it is close to my predicted FG I package the beer. If it seems off I wait longer. I have only had over carbonation problems twice in 107 batches and I think other factors came into play, though I haven't figured out what it was.

 

[50calshooter]

I've never used a hydrometer. I've always used a refractometer. One reading before fermentation and two readings after all activity stopped (48 hours apart). Never ever had any trouble.

 

[kh54s10]

I've never used a hydrometer. I've always used a refractometer. One reading before fermentation and two readings after all activity stopped (48 hours apart). Never ever had any trouble.

Works fine to determine FG stability, not so accurate if you really want an accurate number. But then again a hydrometer might be out of calibration giving inaccurate numbers.

 

[Nemanach]

I use that brewersfriend brix to fg calculator and I find it accurate enough for my purposes. I never use my hydrometer anymore.

 

[50calshooter]

Works fine to determine FG stability, not so accurate if you really want an accurate number. But then again a hydrometer might be out of calibration giving inaccurate numbers.

If refractometers are good enough for breweries and wineries its good enough for me. Its like any thing else: buy quality and use correctly and its fine.

 

[kh54s10]

If refractometers are good enough for breweries and wineries its good enough for me. Its like any thing else: buy quality and use correctly and its fine.

Do you know how a brewery and winery is using them? I would bet if they want very accurate final gravity numbers they are not using a refractometer, or even a standard homebrew hydrometer, but a hydrometer that has a close range to their expected final gravity. Or some other specialized piece of equipment. I really care where my FG ends up so I take one hydrometer reading. That way I don't have to use a calculator to determine the real number....

 

[50calshooter]

I would bet if they want very accurate final gravity numbers they are not using a refractometer, or even a standard homebrew hydrometer, but a hydrometer that has a close range to their expected final gravity. Or some other specialized piece of equipment.

You said "I would bet if..." I'm a little more sure and a little more experienced then "I would bet". I've been using refractometers for decades. Not just in brewing. I've used industry specific refractometers to measure things like how diluted the cooling agent is on million dollar CNC machines like lathes and milling machines for our Family business. Ive used them to measure the ripeness (sugar content) of tree fruit like peaches, oranges, and apricots on farms where I worked. And I use them today to brew award winning beers. "I would bet" refractometers are the right tool for the right job.

 

[kh54s10]

You said "I would bet if..." I'm a little more sure and a little more experienced then "I would bet". I've been using refractometers for decades. Not just in brewing. I've used industry specific refractometers to measure things like how diluted the cooling agent is on million dollar CNC machines like lathes and milling machines for our Family business. Ive used them to measure the ripeness (sugar content) of tree fruit like peaches, oranges, and apricots on farms where I worked. And I use them today to brew award winning beers. "I would bet" refractometers are the right tool for the right job.

All but possibly the last of your examples do not have the problem of needing a calculation to account for the presence of alcohol. From everything I have read the calculations/calculators will correct you very close, but if you truly want an accurate final gravity number, it is almost always suggested that you use a hydrometer instead. Or at least to verify the refractometer.

I really care where my FG ends up so I take one hydrometer reading. That way I don't have to use a calculator to determine the real number....

Just noticed I left out an important word in my reply:
I don't really care where my FG ends up so I take one hydrometer reading.

But this is the real reason that I don't use my refractometer to measure final gravity:
That way I don't have to use a calculator to determine the real number....

 

[50calshooter]

I guess I'm not following you very well. I don't understand what you mean when you say you don't have to use a calculator. My brewing refractometer has a gravity scale that reads just like a hydrometer. What calculations am I having to do that you're not?

 

[LittleRiver]

Refractometers don't read correctly if alcohol is present in the sample. A calculator can account for the alcohol and give a reasonably accurate correction.

 

[dmtaylor]

My brewing refractometer has a gravity scale that reads just like a hydrometer. What calculations am I having to do that you're not?

@LittleRiver is correct. Thou shalt use this calculator or equivalent whenever alcohol is present:

https://www.brewersfriend.com/refractometer-calculator/

 

[Pkrd]

Daily readings are a good way to introduce unwanted oxygen/infections. We all fussed over our ferments when new to brewing but you're better off leaving the yeasties alone to do their thing.

 

[50calshooter]

@LittleRiver is correct. Thou shalt use this calculator or equivalent whenever alcohol is present:

https://www.brewersfriend.com/refractometer-calculator/

Mine has a gravity scale too that reads just like a hydrometer besides having the Brix scale. The calculations are made in the scale.

 

[LittleRiver]

Mine has a gravity scale too that reads just like a hydrometer besides having the Brix scale. The calculations are made in the scale.

We're not getting through to you for some reason. My refractometer has scales just like yours, it will not read accurately if there is alcohol in the sample, neither will yours.

Refractometers will give accurate readings before fermentation. But during and after fermentation alcohol is present, which causes the refractometer to read incorrectly. Thus the need to use a refractometer calculator post fermentation.

If you are just trolling, good job!

 

[dmtaylor]

Ignore the SG scale on your refractometer. It is WRONG and has misled you and thousands of others. You MUST measure only in Brix and use a conversion calculator.

 

[kh54s10]

Ignore the SG scale on your refractometer. It is WRONG and has misled you and thousands of others. You MUST measure only in Brix and use a conversion calculator.

Not necessarily. I have read that some of the scales are uneven Brix to SG. It depends on the refractometer... I checked mine and the scales match. Or at least the few that I checked they were the same. I cannot say 100% that I did everything correctly. That was years ago. My measurements also agree with my hydrometer, again, the last time I checked, years ago.

 

[BrewnWKopperKat]

I have read that some of the scales are uneven Brix to SG.

Brix/SG/Plato Why Use One and Not The Others (/r/homebrewing) has some observations on scales (and calibration) in the comments.

It depends on the refractometer.

^ this ^