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Refractometer reading low

Northern Brewer General
#1

I know there are a lot of threads already about similar issues, but after lots of searching, I couldn’t find an answer.

My refractometer is quite off from my hydrometer. After about 50 extract brews, I’m on my third AG brew and trying to work things out. Two brews ago, I realized things were way off, so I took measurements with my hydrometer and refractometer to compare. I have since read about wort calibration. That seems to make the refract. reading lower. All my hydro readings were higher, after temp conversion. I have the Brix/SG model from NB. Below are my comparisons.

1st runnings - Refract=1.054 - Hydro=1.057
Sparge - Refract=1.031 - Hydro=1.036
Into Fermenter - Refract=1.048 - Hydro=1.056

As for process, I can’t say for certain I let it sit for 30 seconds, but I more than likely re-checked the sample. The outside temps that day were in the mid to upper 80’s. I see the upper temps on the ATC models are 86.

I checked the hydro and refract with distilled water tonight, and they were both very close to being right on (within 0.001 or 0.002).

I’m beating my head against my desk trying to figure this out. Any help would be appreciated!

#2

Without much discussion I think you missed out on the part indicating that the SG reading on the “newer” brix and SG reading models were fooked up. Bottom line use the brix reading only and it will line up apples to apples if both instruments are calibrated.

I dont have a “bad” model so I cant see what the brix number should read. If you relay the true brix and hydro readings for at least one batch we could see right now whats up as I could use a calculator to approximate continuity. As you may understand FG is never reliable or true in refracting wort because of alcohol after fements whereas this is not a concern with a hydro but this fact is different from the first issue I mentioned.

#3

Ya, I got the part about FG. I missed the part about the SG readings being screwed. I got it about a year ago.

When looking into my refract, I gave the brix equivalents below in brackets, if that works.

1st runnings - Refract=1.054 (14 brix) - Hydro=1.057
Sparge - Refract=1.031 (6.9 brix) - Hydro=1.036
Into Fermenter - Refract=1.048 (12.5 brix) - Hydro=1.056

#4

It’s a variable conversion, depending on what formula you use…

#5

[quote=“CCM”]Ya, I got the part about FG. I missed the part about the SG readings being screwed. I got it about a year ago.

When looking into my refract, I gave the brix equivalents below in brackets, if that works.

1st runnings - Refract=1.054 (14 brix) - Hydro=1.057
Sparge - Refract=1.031 (6.9 brix) - Hydro=1.036
Into Fermenter - Refract=1.048 (12.5 brix) - Hydro=1.056[/quote]

HMmm, somethning is not quite right. I am considering the possiblity that your refract reading is user error of 0.2/0.4-1.0 brix which is quite possible these little suckers are hard to read until you understand the calibrate line for the most part. Its hard to discern within 0.4-0.6 sometimes for sure unless you are perfectly dialed into the right shadow of the line when calibrating. Its a learning thing and the more you understand the “shadow” it becomes easier to read.
I would assume your batch sparging as the first running is low and the second running is high.
14-1.059
6.9-1.029
OSG = 12.5-1.053

Lets see something once just looking at OSG.
OSG = 12.5+0.2=12.7-1.053
OSG = 12.5+0.4=12.9-1.054
OSG = 12.5+0.6=13.1-1.055
OSG = 12.5+1.0=13.5-1.057

Also the hydro reading 1.056 at 80f requires a adjustment of +.002 if its calibrated to 60f some are higher it says on the paper within the hydro stem.

I have to think its the cali line on the refract in conjunction with a understanding of where the hydro lies with pure water. IE: If it reads .998 or 1.002 then that’s a few points to be consider and shifted to give true readings and after those bugs are worked out Ill bet they start to agree.

#6

Operator error seems to be a common answer for me lately!

I punched all my numbers into the seanterril spread sheet. When the brix was converted to sg, they all matched my pre-temp conversion numbers. Almost all my hydro readings were done around 118F. I used a digital therm to check the temps each time.

I think I need to concentrate more on getting an accurate reading next brew day.

Sometimes, the line is real fuzzy. Is that from not enough liquid, too much, something else? I definitely give it the whole, close enough eyeball. I’m finding out more and more that doesn’t work for AG, if you want accurate numbers.

#7

Yeah Denny, I have started using Mike Schwartz’s chart from BYO Jan/Feb 2001 over the last two years I have found it the most accurate and always agrees with my hydro.

I’ll see if I can find a link to where I found the sheet as its large and PDF.
Edit* My flub it was Zymurgy from that time frame heres the chart:

http://search.yahoo.com/r/_ylt=A0oG7ml2 ... ertion.pdf

Wowzer, I wonder if this 118f revelation along with a few points from the fuzzy line biz(Im glad you can see what I am speaking too there) has much to do with things. As I understand what your saying a OSG reading in the hydro showing 1.056 (if 60f is the calibrate temp for your hydro)118f would mean your true hydro reading was 1.066 boss. You really need to sample all wort around room temp to be able to see accuracy as there is too much deviance from standard reference temps of 60-70f also which could throw agreements out the window.

Next batch just check the refract to make the dark side of the topof the blue line just hit the 0 mark possibly to then read right under the mark it should be with the blue line top then if you dig what i’m saying.
And reference the hydro around 60f /or compensate then and make note of the reference with distilled.

EDIT?EDIT?EDIT
WAIT/ WhAT your sample to fermentor was 118f it must have been around 70f right?
Which makes the agreement already discussed pretty close again IE: refract(1.053-1.057) Hydro 1.056-1.058/depending on temp of sample) not 1.066

#8

The numbers I gave you were supposedly corrected for temp. I have a chart that says add 0.010 to the reading at 118F. The OSG of 1.056 was around 77F and the actual reading was 1.054.

Next batch…I’ll cool the samples to try and keep things simple.

Thanks for you help!

#9

SPHEww had me worried, I posted the 1.066 and almost doubled over like WHAT!? WAit a sec somethings awry. I think your well on your way to seeing agreement next batch now and you got 'er down.

Cheers,
ITs

#10

[quote=“CCM”]Sometimes, the line is real fuzzy. Is that from not enough liquid, too much, something else? [/quote]A thin coating of liquid, no bubbles and no grain bits, definitely helps and get a good, bright light behind it - I’ll step into the sunlight if possible (CFLs are the worst).

#11

Thanks!

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