Refractometer reading during boil :(

[MarsColonist]

So, a couple of weeks ago, someone stole my keggles from my backyard for scrap metal..... thats a whole 'nother story... I was essentially dialed in well and could consistently hit ~80% brewhouse efficiency over the last 15 batches or so..

Borrowed a friend's keggles (not very different from my old setup at all) while he is moving, and brewed a couple of batches. The two batches both had brewhouse efficiency in the low 60s, if not high 50's. I screwed up a batch sparge on a large grist bill in the first one (final sparge was still at 1.031 after I was done collecting in the kettle), but for the second batch, here's the rub....

I started using a refractometer to monitor the boil rather than my standard single preboil cooled hydrometer reading. I was supposed to hit a preboil of 1.051 to finish at 1.059. I check at the beginning of the boil: 13 Brix (1.053)... I under sparged by about a gallon, so I added some filtered water to get about 13 gals for an 11 gal batch. I check again: 12.5 Brix (1.051). Right on. I check halfway through the boil: 13.7 Brix (1.056). Right on. I check in the last 15 min: Brix 15.1 (1.062) Okay, overshoot. I cool the wort to 70°F. I check the Brix between filling the carboys: Brix 10. (1.040)

WTF!!!!!!!!!!!!!!!

Im thinking it stratified while I let the break cone formed after whirlpool. I check again. Brix 10. I check hydrometer. 1.040. My "ESB" is now likely a really harsh, hoppy Best Bitter (hopped to 44 Rager IBU [30IBU from FWH and 60min addition] for a supposed brewhouse eff of 82%) . Fine. It should be drinkable, but man, thats not what I was shooting for....

Question: Can you not reliably use the refractometer to judge the progress during boil? Im cleaning the refractometer lense, get some wort out of the kettle and put 5-6 drops on the refractometer and read. Am I missing something?

 

[samc]

I'll be in the minority I'm sure but I had unreliable results as well. Only used it once so far but not sure that I will bother with it again. To me it seems like I've invested in all this expensive equipment, brewing software and my time and experience and then I let that all hinge on a quick reading from a $30 made in China meter. In my case even though it gave me numbers that were off I did not adjust from my normal methods and the beer turned out fine and I hit my numbers the old fashioned way.

 

[willynilly]

Is it a temp. compensating refract?

Did you calibrate it?

What was the temp when you calibrated it?

What was the temp. when you were taking your measurements?

Refracts, I have found, are very accurate, even with samples from my BK.

Refracts dont measure sugar alone either, there is always a possibility that you had tainted readings

 

[MarsColonist]

Is it a temp. compensating refract?

Did you calibrate it?

What was the temp when you calibrated it?

What was the temp. when you were taking your measurements?

Refracts, I have found, are very accurate, even with samples from my BK.

Refracts dont measure sugar alone either, there is always a possibility that you had tainted readings

Model number is RHW-25ATC.. the ATC being "Automatic Temp Compensation", so no I dont calibrate. It reads 0 with distilled. Specs are the ATC window is 10°C (50°F) to 30°C (86°F).. those 6 drops into a thin film arent going to retain any kind of ridiculous heat for very long... It has a calibration screw.. but I wouldnt know how to calibrate it for the higher temps when my hydrometers arent accurate at the high temps either... I guess i have something to look up

The tainted reading might be an issue, but I didnt see any noticeable debris on the lense. The caveat is that the flap is broken, so I have to hold it on, but I make sure there is a thin film evenly distributed across the lense under the flap with little or no air bubbles.

 

[MarsColonist]

Apparently, I fail at reading directions (Ive had this thing for awhile, but just started using for the BK). I dont think I was waiting the 30sec the instruction explicitly said in bold are necessary for temp compensation.

 

[willynilly]

Directions are good.

 

[rustynuts]

I have made this very mistake due to not reading the directions completely. I woulda given away my first refractometer after its first batch. lol Luckily, a brew friend of mine educated me...while making fun of me...about the importance of letting the sample cool.