Refractometer malfunction

[baltobrewer]

A bit ago, my wife bought me a refractometer for brewing.....gotta love SWMBO....and I was all excited to put it to work. 2 brew sessions ago I used it for the first time, and for some reason, it seems to be off. I can't figure out why. I was making Jamil's Northern Brown, and the reading on the refractometer at pitch was about 14.5 brix, or about 1.058. I was aiming for more towards 1.050, and I know my system pretty well, efficiency-wise. So I took a hydrometer reading, and guess what.....1.050. The refractometer has ATC, by the way...

I had pre-calibrated the refractometer with RO water and adjusted the null line to zero, so I thought I was all set. I took a final gravity reading on the brown, and it read 9 brix. That's 1.036. My hydrometer read 1.012. And trust me, the brown is NOT 1.036. I've got an experienced enough palate to taste that.

What gives? I don't know what else to do to get this thing calibrated. When I adjust the refractometer to match my hydrometer, the blue gets white at the top again, so it's more like a blue stripe than a solid blue, and it gets fuzzy.

Could I have a bum unit? Any help would be appreciated, as this is frustrating as hell. Here's a pic, BTW

[DannyW]

I've found odd readings when using hot samples too. I suspect the sample is evaporating a significant enough amount that it is throwing off the reading. Now I take my sample from the kettle in a steel spoon - maybe a couple of tablespoons worth - and let it sit on the counter for a few minutes. Then I put a drop on the refract. It has cooled enough that the thin sample won't evaporate away and skew the reading.

As for the final grav - because alcohol is present you cannot directly correlate final hydro and refract readings. There should be a converter in your brewing software that will handle the ugly formula for you though.

[chrishw]

um.... did you use the conversion stuff for the refractometer with the sample that had already fermented? I just use mine on brew day only.

[baltobrewer]

I've found odd readings when using hot samples too. I suspect the sample is evaporating a significant enough amount that it is throwing off the reading. Now I take my sample from the kettle in a steel spoon - maybe a couple of tablespoons worth - and let it sit on the counter for a few minutes. Then I put a drop on the refract. It has cooled enough that the thin sample won't evaporate away and skew the reading.

As for the final grav - because alcohol is present you cannot directly correlate final hydro and refract readings. There should be a converter in your brewing software that will handle the ugly formula for you though.

Oh, shit, I didnt know you couldn't use it for final grav readings. The alcohol skews the reading? Thats good to know.

[Sent From My iPhone]

Promash and Beersmith should correct for alcohol though, right?

[baltobrewer]

I need to futz around with it a bit more

[johnc66]

Here s a really good video and spreadsheet by Chris Graham of More Beer showing how you can use a refractometer for final readings with alcohol....

http://morebeer.com/learn_vids/vids_refract

[bub]

uhh, one thing to check...
is it a BRIX or PLATO hydrometer? There is a 3rd scale out there that looks like brix or plato but isn't and it's close enough to fuck with your head too.
Check that it says Brix or Plato on it somewhere.
BUB