New refractometer doesn't match hyrdometer?!

WorryWort · 07-13-2009, 03:38 AM

Hi,

I just got a refractometer, and used it for the first time today.

It gave a reading of 11 plato on something my 60F hydrometer gave at 1.062.

I'm not sure what's up, especially because they both are accurately calibrated to give distilled water a 'zero' reading!

Any thoughts?

Shonuff · 07-13-2009, 03:45 AM

Did you check the instructions that came with the refractometer and the hydrometer? They need to be corrected/adjusted at different temps

WorryWort · 07-13-2009, 04:44 AM

Thanks, I definitely considered that though.

My hydrometer is configured for 60F, which I've accounted for. And my refractometer is supposedly ATC, meaning that it automatic calibrates to the atmospheric temperature.

Either way, the temp samples and ambient temp were roughly 70F. But I had a 1.015 difference in the readings.

EDIT: I explained ATC wrong above, and I'm aware that ATC refractometers need to be calibrated at a given temp, and I did that.

**weirdboy** · 07-13-2009, 04:53 AM

Quote:

And my refractometer is supposedly ATC, meaning that it automatic calibrates to the atmospheric temperature.

You still need to calibrate it. I have an ATC refractometer but it still says to calibrate it.

WorryWort · 07-13-2009, 05:48 AM

Quote:

Originally Posted by weirdboy

You still need to calibrate it. I have an ATC refractometer but it still says to calibrate it.

Your're right. I minced words, it will work in any temp, but does need to be calibrated. And I did calibrate it. With distilled water, and it read 0.

But it still read the wort wrong compared to the hydrometer.

Orangevango · 07-13-2009, 11:42 AM

did you calibrate the hydrometer with distilled water?

**wehumble** · 07-13-2009, 12:15 PM

I've thought of two things:

Dumb Thing - you are talking about unfermented wort, correct? Alcohol messes with the refractometer reading. (which you probably already know, like I said, dumb thing)

Not so dumb thing - Are you getting a large, bubble-free film of liquid when you close the cover? I've found that a lot of bubbles under the cover can affect the reading.

Oh wait, Three things! - was the wort mixed well for both samples? I've heard of faulty hydro readings due to stratification in wort.

cactusgarrett · 07-13-2009, 12:26 PM

Isn't there a correction factor, which is specific to each wort, needing to be used when measuring unfermented wort? I know each wort i produce, the correction factor is slightly different each time, and i can see this difference producing the problem the OP has stated above. I use beersmith, which has a "calibrate hydrometer" setting to generate this correction factor.

Just a thought.

**wehumble** · 07-13-2009, 02:55 PM

Quote:

Originally Posted by cactusgarrett

Isn't there a correction factor, which is specific to each wort, needing to be used when measuring unfermented wort? I know each wort i produce, the correction factor is slightly different each time, and i can see this difference producing the problem the OP has stated above. I use beersmith, which has a "calibrate hydrometer" setting to generate this correction factor.

Just a thought.

I think the correction factor you are talking about is to adjust for slight errors in how a hydrometer reads. For instance, one that reads 1.001 in distilled water at calibration temp needs to be corrected .001 (should read 1.000)

The refractometer calibration in Beersmith is a way to get your hydrometer reading and refractometer reading to agree. After it's set, the two instruments will agree for unfermented wort. As I said, fermenting wort has to have another correction applied (which Beersmith will also do), but that is separate from the 'calibration'.

sharpstick · 07-13-2009, 03:09 PM

Quote:

Originally Posted by wehumble

I think the correction factor you are talking about is to adjust for slight errors in how a hydrometer reads. For instance, one that reads 1.001 in distilled water at calibration temp needs to be corrected .001 (should read 1.000)

complete calibration requires a second reading at higher density that you make with pickling salt and create a correction curve.
cheap hydrometers, usually most of the full range triple scale ones, are not very accurate. you're better off with a set of 3 narrow range hydrometers. they are more expensive, about $15 to $25 each, but made to higher standards, and are a LOT easier to read because the marks are farther apart.