weird results measuring OG with refractometer

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Bribie G

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Ok, the wort has been run into cubes, I usually get an extra 1 litre Schott bottle as well to chuck in or use for starter, and there's some wasted trub and wort in the bottom of the urn. What I have done a few times is forgotten to do a refrac reading, so no worries I let it all settle down overnight and there is enough clear wort on top of the trub in the urn to put a pipette in and draw off a few drops for the refrac reading.

What always seems to happen is that for a calculated 1050 brew (my current AusPA brew) the drops out of the urn weigh in at around 1045 - momentary panic. I take a few more samples. 1045.
Then I sneak some out of the Schott bottle that was run off at the same time as the cubes.

1052

:blink:

This has happened several times, I wonder what is going on,are there sugar gremlins sneaking stuff out of the urn trub overnight?
 

iralosavic

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I assume if there are deviances in temperature between samples that they all fall within the auto compensation range of the refractometer?
 

Stagwa

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Hi Bribie,

Could the wort be getting diluted by the condensation that forms inside the urn?

Cheers,
Stagwa
 

Nick JD

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You could stir up the urn contents, let settle and then measure...
 

Nick JD

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Are you getting sharp defined lines with both measurements?
 

QldKev

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I would try and clarify both samples and see what you get.
 

keifer33

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Nick JD said:
Are you getting sharp defined lines with both measurements?
This is my current problem, can calibrate as much as I want the lines are always blurry. Might have to get a hydrometer to use as a backup.
 

spudfarmerboy

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You may have density stratification in your vessel.
Do what Nick suggests, stir the vessel and recheck.
 

krausenhaus

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spudfarmerboy said:
You may have density stratification in your vessel.
Do what Nick suggests, stir the vessel and recheck.
Happened to me the other day.. First runnings plus two batch sparges in the kettle, checked the gravity and was 4 points off. Gave it a stir, checked again, spot on.
 

The Village Idiot

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Happens every time for me..... strange readings post boil. Is the wort too hot, break material giving odd readings, poor efficiency????? I have decided to run with what I get as I have added some dex/sugar a couple of times to "correct" things and ended up with very strong beer(not that this is bad)
 

slash22000

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Do people usually get "sharp defined lines" with refractometers? How "sharp" are we talking here? :huh:

Mine has always been blurry, at least blurry enough that I basically flip a coin to decide between two neighbouring 0.2 brix increments. I'm not entering any competitions or anything so I've never worried THAT much about it.

Quick Google image search, mine tends to look like this.

How would you guys read that result there? I would probably say, 9.2? Maybe 9.4?
 

Nick JD

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Having bits of crap in the sample blurs the reading.
 

tiprya

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I get a pretty sharp reading post-boil.

During fermentation it's more blurry due to trub (pour and leave 15 minutes before using on refrac) and co2 in solution (I've found flicking the refrac can push the bubbles out). Those two tricks make my readings pretty sharp.
 

mikec

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Sunlight gives me a sharper reading than indoor lights do.
 

Bribie G

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The Village Idiot said:
Happens every time for me..... strange readings post boil. Is the wort too hot, break material giving odd readings, poor efficiency????? I have decided to run with what I get as I have added some dex/sugar a couple of times to "correct" things and ended up with very strong beer(not that this is bad)
Could be some sort of stratification going on. Next brew I'll collect a small bottle "midstream" like a piss sample while I'm filling cubes and use that for my refrac reading. I get a good sharp line using clear wort, the refrac is usually spot on, having checked with sugaz solution etc.

Re the quote, my very first AG brew I didn't do a hydrometer reading and didn't have a refrac in those days. The wort tasted very unsweet compared to KnK so I thought the mash might somehow have "failed", and added a kilo of dex to compensate. Beer was glorious but after five pints each my mate and I were staggering and crawling around and weeping for Princess Di, also
. :lol:

Five years ago, yup that would be right. Time flies when your'e having grog.
 
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Aces High

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Bribie G said:
Could be some sort of stratification going on. Next brew I'll collect a small bottle "midstream" like a piss sample while I'm filling cubes and use that for my refrac reading. I get a good sharp line using clear wort, the refrac is usually spot on, having checked with sugaz solution etc.
This was what i was going to say. if i pull a sample from the tap during the mash it can be up to 1060 when the top of the mash is around 1020. This is BIAB with around 65L of water and 10kg of grain. Ive been caught out a few times thinking i'd had no conversion at all only to find out all is well.

There is definitely some major statification going on even after an hour
 

BobtheBrewer

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tiprya said:
I get a pretty sharp reading post-boil.

During fermentation it's more blurry due to trub (pour and leave 15 minutes before using on refrac) and co2 in solution (I've found flicking the refrac can push the bubbles out). Those two tricks make my readings pretty sharp.
I was under the impression that a refractometer only measured unfermented wort.
 

slash22000

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False. You can read fermenting gravity with a refractometer, you just need to use a calcuator program to fix the value to accommodate for the alcohol etc. You can find about 25,000 of them all over the net.
 

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