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Old 11-29-2010, 03:06 AM   #1
wendelgee2
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Default Varying OG Readings from a Refractometer

Hey folks,
Just brewed up an AG batch and had a weird experience.

At the end of the boil I grabbed a little sample for an OG test with the itty-bitty turkey baster/pipette thing that came with my refractometer. I set the sample aside for a while until the wort was cool and on its way into the fermentor. I then checked the sample, and it was low. Shockingly low - 1.062 when I was going for 1.081. At this point, the wort is almost completely into the fermenter, so it's a little late for a hydrometer reading.

So I clean off the refractometer and put in some water to see if it was properly calibrated. It reads 1.000.

I then pull off a bit of whatever wort is leftover in the kettle. Let it sit in a glass and separate (it's the full of break and hops, of course). When it does, it now reads 1.072.

That's better, but still off. Mostly, I'm confused as to why the refractometer would give different readings on different samples. This particular model is supposed to account for temp...but maybe not.

Maybe it's time to just go back to the trusty hydrometer...



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Old 11-29-2010, 05:18 AM   #2
BrewNinja1
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Its because your wort will stratify. You need to mix it up, then take the sample right away. I just use my plastic mash paddle. I give it a big stir, then take a drip or two off of the end. I have found the ATC only semi-works. On my refractometer it reads .5 brix lower when its hot.

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Old 11-29-2010, 05:57 PM   #3
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Quote:
Originally Posted by BrewNinja1 View Post
Its because your wort will stratify. You need to mix it up, then take the sample right away. I just use my plastic mash paddle. I give it a big stir, then take a drip or two off of the end. I have found the ATC only semi-works. On my refractometer it reads .5 brix lower when its hot.
That makes sense...I'm just surprised by the amount it differed. Clearly you're right, though.

(Also, did calculations for a 5gal batch, not 5.5, which is why I missed by gravity so badly.)
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