How do you take Refractometer readings?

[jeeppilot]

I’m curious how you all take Refractometer readings?

I have been conservative with my recipes as I’m sort of new to BIAB, planning 75% eff and my last several batches have been right on. Today however, I set my crush a bit finer, and was shooting for a sessionable OG of 1.038. I hit 1.040 PRE-BOIL. Measured 3 times. That’s a 95% conversion efficiency. Then after boiling off about 1.25 gallons, I measured again and 1.040. Measured 3 times. So I still ended very near my target OG, but my readings have to be at fault, right?

 

[blubrewbbq]

I’m curious how you all take Refractometer readings?

I have been conservative with my recipes as I’m sort of new to BIAB, planning 75% eff and my last several batches have been right on. Today however, I set my crush a bit finer, and was shooting for a sessionable OG of 1.038. I hit 1.040 PRE-BOIL. Measured 3 times. That’s a 95% conversion efficiency. Then after boiling off about 1.25 gallons, I measured again and 1.040. Measured 3 times. So I still ended very near my target OG, but my readings have to be at fault, right?

Did you let the wort cool before taking the reading? Even pulling from mash at 150 degrees plus is still a bit hot.

How much grain was in your grain bill?

 

[jeeppilot]

Did you let the wort cool before taking the reading? Even pulling from mash at 150 degrees plus is still a bit hot.

How much grain was in your grain bill?

Yeah I take a very small sample and let it sit on the spoon to cool for a bit before I put it on the refrac.

My recipe was 7.5 lbs of grain, with an estimated pre-boil gravity of 1.030 and target OG of 1.038.

 

[blubrewbbq]

Yeah I take a very small sample and let it sit on the spoon to cool for a bit before I put it on the refrac.

My recipe was 7.5 lbs of grain, with an estimated pre-boil gravity of 1.030 and target OG of 1.038.

That is interesting. Your situation happened to me one time pre-boil. My issue was that I needed to stir the wort a little to make sure everything mixed in evenly. Once I did that readings were good.

 

[jeeppilot]

That is interesting. Your situation happened to me one time pre-boil. My issue was that I needed to stir the wort a little to make sure everything mixed in evenly. Once I did that readings were good.

I stir very well before I measure. Sometimes I feel almost to my detriment. My readings are frequently varying by 5 points or more and I feel like I have to regularly take 2-3 measurements to feel confident.

For detail, I take a conversion sample usually at 45 minutes into the mash by stirring vigorously, then taking a sample trying to avoid any grist. I’ll confirm that number after I hoist the bag from the kettle and have a nice clean sample. Again, stirred well. For post-boil, I’ll grab a sample with my spoon for a boil bubble, let it cool then check. I’ll double check that number as by sticking my refractometer into the stream of wort coming from my CFC into the fermenter.

 

[balrog]

I have found a couple of things with measuring pre boil refractomoeter.

1) I stir the crap out of it and DO NOT LET IT SIT ON THE BIG OLE GIANT SPOON after stirring -- I think it evaporates and reads high because of it
2) As the kettle heats up, the R% goes up, even taking time to let the refractometer cool. Again, I think it might be the evaporative thing.

I have to measure by stirring, taking a whole giant spoonful and pouring it over the refactometer and flipping the plate down immediately. In that manner I get repeatable readings. But all bets are off as kettle approaches boil.

All this could be the crappy tool, or the crappy person reading the crappy tool.

 

[Nebraskan]

Put a small bowl or glass in the freezer. Take a sample... SMALL bit, and put in the bowl. Let it sit for about 30 seconds and then take a small drop and put on your refractometer. They will always work better near the 60deg F temp for a good reading. Some are better than others.
Put a small bowl or glass in the freezer. Take a sample... SMALL bit, and put in the bowl. Let it sit for about 30 seconds and then take a small drop and put on your refractometer. They will always work better near the 60deg F temp for a good reading. Some are better than others.

 

[jturman35]

Put a small bowl or glass in the freezer. Take a sample... SMALL bit, and put in the bowl. Let it sit for about 30 seconds and then take a small drop and put on your refractometer. They will always work better near the 60deg F temp for a good reading. Some are better than others.
Put a small bowl or glass in the freezer. Take a sample... SMALL bit, and put in the bowl. Let it sit for about 30 seconds and then take a small drop and put on your refractometer. They will always work better near the 60deg F temp for a good reading. Some are better than others.

This is what I do and take several readings to confirm. I use my digital thermometer to make sure temp s close to 60deg.

 

[sleizure]

Hey, great topic. Can you all define what is preboil? For me, I'm using a robobrew, and after my sparge my vessel is approximately 200 ish degrees. That is when I pull my sample for both the refractometer and hydrometer. I notice at high temps my refractometer is approx .005 higher than the hydrometer. At closer to room tempertatures, they are close within .001.

When should I be taking my measurements?