Refractometer question

I'm new to using a refractometer and I brewed up a batch of all grain witbier lastnight. The final colour of it is pretty light. I took one of the pipettes that came with it and grabbed a sample just before the boil. Squirted it into a small sample cup I had to chill a bit before applying it to the window of the refractometer. After putting it on, I held it up to the light and the blue line was way over top of the scale and the scale goes all the way up to 1.080. Ended up siphoning a sample into a larger beaker and used a hydrometer. Ended up getting a pre boil reading of 1.050. I calibrated the refractometer with water pre-use and zero'd it out. The instructions it came with were less than helpful and any YouTube videos I watch aren't helping me either. Does anyone have any suggestions for me?

Thanks in advance.

*refractometer isn't a cheap knock off either. Got it from northern brewer and paid $60.

If I recall, distilled water is best for calibration and your instrument should have come with a tiny screw driver to make any needed adjustments. Just using a drop of wort even if it is warm will quickly cool on the glass.

I did the calibration with distilled and 0'd it out. Still couldn't get the damn thing to read OG correctly. I'll have to give it another go with the sample I saved to try.

Just out of curiosity, did you temperature compensate for your hydrometer reading? Higher temp will give you a lower reading.

Use the Brix scale instead of OG if your refractometer has it. The gravity scale is inaccurate on some models.

Hey BrotherGrim, at first I did. I used my wort thermometer to get the temp then I compensated. I also left the hydrometer in the wort until it reached room temp and it was confirmed 1.050.

Thanks for the tip as well oujens. I'll keep a conversion chart handy.

I may have solved the problem though. It just so happens I have 2 batches (one American Stout and one IPA) in secondary big bubblers. I took a large beaker sample of each and used my hydrometer. Got the FG of the stout and calibrated the refractometer to that. Took the FG of the IPA and whatever calibration I made using the stout matched the IPA hydrometer reading. Took a small sample of the witbier I have fermenting and low and behold it read it to be 1.040 which makes sense as it's been actively fermenting from the OG 1.050. Perhaps my "distilled" water wasn't cutting it. I'll know for sure once the witbier stops fermenting if I've dialled it in.

Tyso22, you probably know that refractometers are not accurate when alcohol is present as alcohol throws off the reading. Once fermentation has started you're better off sticking to your hydrometer. I only use my refractometer for pre-fermentation readings.

As the hot sample cools in the cup, water evaporates and is increasing the concentration of the sample. After fermentation begins the refractometer in increasingly inaccurate due to the presence of alcohol. There is a conversion chart but some question the accuracy choosing to use a hydrometer instead. I place a few drops of the hot wort on the sample window, close the lid and read the blue line immediately with good results.

Thanks brew! I actually do remember reading that but it definitely slipped my mind. Perhaps I didn't figure this thing out lol.

And thanks bigdaddybrew as well.

I guess this means I'll just have to brew a bunch more batches so I can dial in my refractometer right lol! Yea, that should solve it!

I get reasonable reading at mash temp, but the closer it get to boiling they tend to read high.

I use this calculator once the beer starts fermenting.
http://seanterrill.com/2012/01/06/refractometer-calculator/

I check the final gravity at kegging with a hydrometer and the calculated values are normally within about a point of the hydrometer as long as the FG is above 1.010.

You should have a wort correction factor for your refractometer.
You need to perform a series of tests with it comparing to the hydrometer for correction.
Doing this over many tests gives you an average and allows you to compensate when sampling. http://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/
Normally it would not be the difference between 1080 and 1050 but it will make a difference.
After you have your WCF determined plug it in here and it will calculate for you. http://www.brewersfriend.com/refractometer-calculator/
Additionally the whole purpose of the refractometer is not to have to cool the sample first. Place a couple drops on the glass, close the window, wait 30 seconds and read.
I don't use a refractometer after fermentation starts so I have no reliable data for that.

sky4meplease said:

You should have a wort correction factor for your refractometer.
You need to perform a series of tests with it comparing to the hydrometer for correction.
Doing this over many tests gives you an average and allows you to compensate when sampling. http://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/
Normally it would not be the difference between 1080 and 1050 but it will make a difference.
After you have your WCF determined plug it in here and it will calculate for you. http://www.brewersfriend.com/refractometer-calculator/
Additionally the whole purpose of the refractometer is not to have to cool the sample first. Place a couple drops on the glass, close the window, wait 30 seconds and read.
I don't use a refractometer after fermentation starts so I have no reliable data for that.

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Thanks so much for this! This info comes at a great time as I will have quite a few batches getting brewed up in the next few weeks. I think this will prove to be very useful. Much appreciated.

I find that if I zero out the refractometer, then take a sample it takes only a minute or two to cool and for the reading to stabilize. I don't know my model but it is an ATC model. As stated I only use it preboil because of the inaccuracy due to alcohol. I have tried the correction calculators but haven't gotten reliable conversions.

kh54s10 said:

I find that if I zero out the refractometer, then take a sample it takes only a minute or two to cool and for the reading to stabilize. I don't know my model but it is an ATC model. As stated I only use it preboil because of the inaccuracy due to alcohol. I have tried the correction calculators but haven't gotten reliable conversions.

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Why can't you use it post boil, pre fermentation? I have only recently gotten a refractometer, but I thought you were supposed to use it after boil, before pitching the yeast.

I have had several issues with my refractometer when I use it on really cold days. Seems the temperature correction is very inaccurate. So I have been leaving it inside and taking the sample to it and getting much better, consistent results.

KennyPowers55 said:

Why can't you use it post boil, pre fermentation? I have only recently gotten a refractometer, but I thought you were supposed to use it after boil, before pitching the yeast.

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OOPS!!! I meant pre-fermentation!