Refractometer Question

[rice13]

My understanding is the a refractometer will not accurately gauge FG due to the presence of alcohol and a hydrometer should be used instead. Can I still use the refractometer to gauge if fermentation is done by comparing the readings a few days apart? In other words will a refractometer give me stable readings even though they may be inaccurate?

I used the refractometer during mash and my plan is to check today, then compare in a few days before taking a final reading before kegging.

Thanks in advance for the advice!

 

[Hopsimus]

I'm gonna say yes. At least I hope so, because I've used mine that way a couple times with that purpose in mind.
I've also used it to gauge when to do a diacetyl rest in a lager.

Cheers!

 

[Yooper]

Sure. You may not get an accurate reading, but when it stops changing, it's finished.

Then you can use some correction software to get an estimate. Sometimes they are pretty close.

 

[Shawn3997]

All I use anymore is a refractometer. This will get you within a point +/-:

http://seanterrill.com/2012/01/06/refractometer-calculator/

I can't read a hydrometer to within a point anyway.

 

[rice13]

Thanks all for the feedback

All I use anymore is a refractometer. This will get you within a point +/-:

http://seanterrill.com/2012/01/06/refractometer-calculator/

I can't read a hydrometer to within a point anyway.

Shawn3997 - did you use the spreadsheet to determine your wort correction factor or just going with the default?

 

[day_trippr]

[...]I can't read a hydrometer to within a point anyway.

lol! Exactly - and I can't read a refractometer within one point, either, so it's all good

Cheers!

 

[greyghost]

lol! Exactly - and I can't read a refractometer within one point, either, so it's all good

Cheers!

Thats why I got a digital

 

[Shawn3997]

Thanks all for the feedback



Shawn3997 - did you use the spreadsheet to determine your wort correction factor or just going with the default?

I just use whatever the default is and it gets me within a point +/- SG (compared to my hydrometer) so I'm good. I'm not sure my hydrometer is calibrated that accurately so who knows which is actually correct?

 

[AZCoolerBrewer]

Soooooo, just horning in on this thread because my wife bought me a refractometer for my birthday and I’m geeking out a little bit. I measured this dark rum on a whim thinking, “I’m not even going to get a reading because 40% ABV will not even give me a reading”. That’s the coolest thing about scientific instruments, they give you the reading that it gives you, not the reading that you think it should give you. The rum read 18 Plato, I’m like, “What’s going on in this crazy world.” Turns out, I think that the rum has a butt ton of sugar in it and that’s why the reading is so high. Science! Very cool.

 

[dmtaylor]

Where there's a will, there's a way, to understand how to use a refractometer properly to match a hydrometer every single time. Very long read here, but top of page 2 by yours truly is very important to understand.

https://www.homebrewersassociation.org/forum/index.php?topic=28544.0

 

[Shawn3997]

Thanks all for the feedback



Shawn3997 - did you use the spreadsheet to determine your wort correction factor or just going with the default?

I've compared what I get from the refractometer with what I get using the hydrometer and they are within a point of each other on average. Close enough for me.

 

[Shawn3997]

Soooooo, just horning in on this thread because my wife bought me a refractometer for my birthday and I’m geeking out a little bit. I measured this dark rum on a whim thinking, “I’m not even going to get a reading because 40% ABV will not even give me a reading”. That’s the coolest thing about scientific instruments, they give you the reading that it gives you, not the reading that you think it should give you. The rum read 18 Plato, I’m like, “What’s going on in this crazy world.” Turns out, I think that the rum has a butt ton of sugar in it and that’s why the reading is so high. Science! Very cool.

You are getting a false reading because of the alcohol in the rum bending the light differently than the water. The refractometer assumes you are just measuring sugars and water.

 

[AZCoolerBrewer]

You are getting a false reading because of the alcohol in the rum bending the light differently than the water. The refractometer assumes you are just measuring sugars and water.

I was thinking about that after I posted. I think you’re right. When people come on here and post about a stuck fermentation because they measured with a refractometer. The alcohol is just as likely to make the reading high as the sugar.