Refractometer Issue

[mbbransc]

I've been using a refractometer for over a year; measuring both original and final gravity. I use Sean Terrill's formula to calculate an accurate FG and ABV. This has worked fine many batches of beer.

I currently have a Flanders (2-mo), Quad (1-mo), Imperial Stout (1-mo) and IPA (2-wks) sitting in fermentors. I measured all their gravities with the same refractometer, entered the numbers in Sean Terrill's formula and all came back between 40-50% attenuation. I was VERY worried so I pulled samples to taste and none of the beers tasted under-attenuated.

To ease my mind, I pulled out the ole faithful hydrometer and took a measurement of the Quad, 1.010 versus a calculated 1.040 using refractometer and formula (89% attenuation).

So I then assumed my refractometer calibration must be WAY off. So I pulled a sample of distilled water, warmed it up to room temp and it measured 0° brixx.

So, what happened? Why was my refractometer and formula working fine for 34 batches of beer and now suddenly not work? Is it busted somehow? Can I fix it? Anyone experience anything similar?

thx

 

[Bowtiebrewery]

Anytime you throw alcohol into the mix, your FG reading is going to be wrong. I know with the calculators out there they sort of work... But for me... Use a hydrometer for finishing gravities... It leaves nothing to chance if its calibrated.

 

[mbbransc]

I understand that and am OK with the estimate. But I don't understand how it worked for 34 batches and now doesn't work anymore. I'm leery now about using it to measure OG.

 

[hunter_le five]

I understand that and am OK with the estimate. But I don't understand how it worked for 34 batches and now doesn't work anymore. I'm leery now about using it to measure OG.

Luck? I don't know. I've tried using the calculators a few times for FG, but they never seem to match anywhere close to my hydrometer reading. These days I will use a refractometer for anything prior to pitching yeast, but hydrometer-only afterword.

 

[mbbransc]

Guess that's where it leaves me. It's just a pain pulling out a large enough sample to use the hydrometer.

Thanks

 

[hunter_le five]

Carboy?

 

[mbbransc]

Carboy and buckets. Just depends on what I have available. Most of my sours end up in 5gal carboys freeing up the 6.5gal ones for new batches. But like right now, one of those is full so the IPA is 5-gal in one carboy and 5-gal in a bucket.

 

[KBL]

I have an excel spreadsheet from more beer that works great. Here is a dropbox link to the excel file.

https://www.dropbox.com/s/3xaej3hw7h1qc66/Refractometer.xlsx?dl=0

 

[chickypad]

Not sure if it helps your issue but I've done 30+ batches using Sean's calculations against a hydrometer reading. About 3/4 have been within .001 gravity pt, and the only 2 batches that did not measure within .002 gravity pts of the hydro reading were Belgians that went under 1.004. I think in the setting of very high attenuation the calculator is not so accurate (might be he mentions that on his site?). It does seem odd though that suddenly happened for 4 beers in a row. Besides checking your refractometer with distilled have you checked it on some OG readings against a hydrometer to see if it still correlates?

 

[mbbransc]

Not sure if it helps your issue but I've done 30+ batches using Sean's calculations against a hydrometer reading. About 3/4 have been within .001 gravity pt, and the only 2 batches that did not measure within .002 gravity pts of the hydro reading were Belgians that went under 1.004. I think in the setting of very high attenuation the calculator is not so accurate (might be he mentions that on his site?). It does seem odd though that suddenly happened for 4 beers in a row. Besides checking your refractometer with distilled have you checked it on some OG readings against a hydrometer to see if it still correlates?

That's a good suggestion. Planning another batch on 04/18 so I'll try it then to see what's what.