Refractometer Issues

[Indytruks138]

I just bought my first refractometer, after breaking countless hydrometers I decided its time to upgrade.

I calibrated with tap water, I know it says to use distilled but I can't imagine tap would throw it off more than a percentage of a brix. When I tested OG it came out pretty accurate, but testing the final gravity and one going into secondary, I got close to 12-13 brix when the hydrometer showed it was 1.013. Any clue why it is this off?

 

[disney7]

The alcohol in the fermented beer throws the refractometer off, as it was only designed to measure non-fermented sugar solutions.

If you know the OG, you take the reading from the refractometer (of the fermented beer) and run it through a calculation to determine the FG. Google for refractometer calculator and you'll find plenty of them.

I use an iPhone app called BeerAlchemy for it.

 

[Indytruks138]

Thank you Disney, I knew I had to be doing something wrong.

 

[disney7]

Here is some more info for you:

http://***********/stories/projects-and-equipment/article/indices/29-equipment/1343-refractometers

http://www.petedrinks.com/refractometer-abv-calculator/

Just curious, from the numbers you posted it sounds like this was a pretty high gravity beer, about 1.109 OG and about 12.9% ABV, is that right?

 

[FuzzeWuzze]

Make sure you calibrate your refractometer too, using distilled water and a known wort solution with hydrometer.

The default correction factor every tool uses is 1.04 but that's just a good guess, mine ended up being 1.026 or something and its slowly moving a bit as I add more data points.