Refractometer issue

[jjbanks]

I went to check my RIS after 2.5 weeks in primary. OG 1.090. FG supposed to be around 1.020.

First time using my refractometer which i calibrated yesterday using distilled water I just bought from Weis. I grab a sample with the syringe looking thing...10brix which comes out to 1.040. I was shocked as I used a blowoff tube and this thing was bubbling away for 3-4 days pretty vigorously.

In my rage I grab and sanitize my hydrometer and get a reason of 1.020.

Any reason why? Did I not calibrate properly.? With distilled water it was calibrated to 0. Any help/insight would be appreciated. See pics.View attachment ImageUploadedByHome Brew1420678673.746501.jpgView attachment ImageUploadedByHome Brew1420678692.206993.jpg

 

[b-boy]

Did you run the refractometer reading through a calculator? Refractometers are really good at measuring sugar in unfermented wort. Once the wort turns into beer, the alcohol causes the refractometer to give bad results. There are calculators which will take your reading and correct it for you.

Here's an example: http://www.brewersfriend.com/refractometer-calculator/

To get a good value you need the original reading (Brix or OG) and the current reading (Brix). If you plug your numbers in (1.090 OG/10 Brix FG) you get 1.012 as your FG. ~11% ABV.

Since you don't have an initial reading taken with your refractometer, the 1.012 may be off a little, but it should be pretty close. In your hydrometer picture I see 1.016.

 

[jjbanks]

Did you run the refractometer reading through a calculator? Refractometers are really good at measuring sugar in unfermented wort. Once the wort turns into beer, the alcohol causes the refractometer to give bad results. There are calculators which will take your reading and correct it for you.



Here's an example: http://www.brewersfriend.com/refractometer-calculator/



To get a good value you need the original reading (Brix or OG) and the current reading (Brix). If you plug your numbers in (1.090 OG/10 Brix FG) you get 1.012 as your FG. ~11% ABV.



Since you don't have an initial reading taken with your refractometer, the 1.012 may be off a little, but it should be pretty close. In hydrometer your picture I see 1.016.

Thanks for the explanation. I had no idea refractometers couldn't read FG brix without a calculation. I guess 1.012 and 1.016 is pretty close.

 

[b-boy]

I'll still take a refractometer over a hydrometer. They are much easier to work with, and you don't need to take large samples. There are a lot of people who will argue this point.

Only down side is you don't get to drink the large samples.

The only issue I've had with a refractometer was in very cold weather (~5F) in my garage. They are useless. However, you can still take your sample inside and test it there without a problem.

 

[jjbanks]

I'll still take a refractometer over a hydrometer. They are much easier to work with, and you don't need to take large samples. There are a lot of people who will argue this point.



Only down side is you don't get to drink the large samples.



The only issue I've had with a refractometer was in very cold weather (~5F) in my garage. They are useless. However, you can still take your sample inside and test it there without a problem.

Another question: how do you determine the wort correction factor in that calculation? Not sure what that means.

 

[b-boy]

I don't use that calculator. I use the one in BeerSmith. I just pulled that out as an example so you could see it. BeerSmith doesn't have that parameter. There are a lot of calculators out there. The online version I normally use requires OG in Brix, which you didn't supply.

 

[LLBeanJ]

Only down side is you don't get to drink the large samples.

That right there is the deal breaker for me as far as using a refractometer for FG. The only reason I bother with the FG reading is to drink the sample.

 

[IslandLizard]

Another question: how do you determine the wort correction factor in that calculation? Not sure what that means.

Determine Wort Correction Factor.

 

[b-boy]

So it's a correction factor based on multiple readings from your device. Yeesh - that's a lot of work. I'm Ok with 'close enough'.

 

[renrutle]

There is a good explanation of refractometer use and calculation of the Wort Correction Factor at Brewer's Friend. See this link.

http://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/

I completed their spreadsheet in one evening by starting with 1 cup of water and 2 oz of DME. I took the 5 refractometer and 1 hydrometer readings for this wort poured it back into my mixing bowl, added 1/4 cup of water, refilled the sample tube and took 5 readings again. Rinse and repeat with 4 more 1/4 cup additions to complete the 30 total readings.

Check these links for additional info and a calculator.

http://www.brewersfriend.com/2013/0...rrectly-for-maximum-accuracy-in-home-brewing/

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

As others have stated once fermentation begins you can't directly convert a Brix reading to SG. A calculation using the OG is necessary to account for the production of alcohol. Go math!

 

[jjbanks]

There is a good explanation of refractometer use and calculation of the Wort Correction Factor at Brewer's Friend. See this link.



http://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/



I completed their spreadsheet in one evening by starting with 1 cup of water and 2 oz of DME. I took the 5 refractometer and 1 hydrometer readings for this wort poured it back into my mixing bowl, added 1/4 cup of water, refilled the sample tube and took 5 readings again. Rinse and repeat with 4 more 1/4 cup additions to complete the 30 total readings.



Check these links for additional info and a calculator.



http://www.brewersfriend.com/2013/0...rrectly-for-maximum-accuracy-in-home-brewing/



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



As others have stated once fermentation begins you can't directly convert a Brix reading to SG. A calculation using the OG is necessary to account for the production of alcohol. Go math!

Well then I will have to wait for my next batch (this weekend) to use from the starting point. I will look through the other links provided later but thanks for the responses. ❤️

 

[IslandLizard]

So it's a correction factor based on multiple readings from your device. Yeesh - that's a lot of work. I'm Ok with 'close enough'.

Yeah, it looks like a lot more bother than it's worth.
I'm with you, I just wing it. Close it good enough, but I do take a real FG hydrometer reading when filling the keg.

I wonder if you take a reading with a calibrated hydrometer, then the refractometer, and adjust the WCF until it comes out even.

 

[b-boy]

I stand corrected BeerSmith does have this factor.

When I set it up I calibrated the refractometer, and compared a sample reading between the hydrometer and refractometer. Beersmith calculated my value as 1.02861 and uses it automatically. I forgot all about that.

When I plug this factor in I get 1.015 instead of 1.012.

This is good to know.

You learn something new (or something you've completely forgotten about) on this site every day. Thanks!

 

[pdxal]

Sean Terrill has a great website with a calculator for refractometer correction. It includes a discussion about the wort correction factor he developed here:

http://seanterrill.com/2010/07/20/toward-a-better-refractometer-correlation/