I'm confused about new refractometer and ATC auto temperature correction...

[Rolly]

I just purchased the refractometer from AHS that has brix/gravity. It says it has automatic temperature correction.

Does this mean I only need to calibrate it with distilled water right out of the box, then I don't need to do it again? So going forward I can put 3 drops of boiling wort on the plate and it will give me an accurate reading, regardless of ambient temperature in the room?

The instructions were obviously written in China so they aren't exactly crystal clear. I'm just hoping I don't have to constantly calibrate and make adjustments to the reading. If I had to go through all that everytime I think I'd just go back to a hydrometer.

 

[GilaMinumBeer]

ATC does not correct for sample temperature.

ATC corrects for instrument temperature within a given range. For example, the difference between moving the refractometer indoors and out.

You still need to let you wort sample cool down, reasonable, before you take a reading but since the sample size is so small it does not take long at all.

 

[Revvy]

Calibrating with distilled water is pretty easy and quick to do, I do it all the time . And I find that it doesn't seem to take much jarring to knock it out of whack, so I just calibrate it every time.

I just picked up a small plastic testube with a screw lid, like these,

And I just keep it in the pouch the refractometer came in with distilled water. First thing I do before using it every time is just calibrate it. It just takes 5 seconds or so.

 

[Homercidal]

Good idea on the distilled water. I can use an old White Labs yeast vial to hold some!

 

[GilaMinumBeer]

For sample cooling, I keep a "Spot plate" aka Coors Plate.

I usually draw two sets of samples and when there is time to sit back I'll re-check my samples for accuracy.

 

[Revvy]

Good idea on the distilled water. I can use an old White Labs yeast vial to hold some!

You can also rubber band that little pipette to the tube so you don't lose it.

 

[Rolly]

Thanks Revvy. I think keeping a small vial of RO water with the refracto would make it much simpler.

 

[Rolly]

So would you say you could put boiling wort on the plate, wait about 30 seconds and the temperature should be good for an accurate reading? I just don't wanna "take the temperature" of the wort sample. Too many steps.

 

[Revvy]

I just draw the pipette full and wave it around a bit for a minute or so. It's such a small sample it shouldn't take all that time to cool off the one or two drops worth in there.

 

[hinke]

Maybe a stupid question but won't some of the liquid evaporate while you wait and thus give a more concentrated liquid?

I notice on my digital refractometer that if I wait the Brix keeps increasing.

 

[Homercidal]

You still want to cool it as quick as you can. It's just MUCH faster in that little pipette than waiting for a hydro tube.

I'd be leery of chilling it too much too. Might be hard to measure the temp of a very small sample.

I usually do what Revvy does and suck some into the pipette and either wave it around or dunk the bulb end in a glass of water (or beer if it's handy) to chill quickly.

 

[Bobby_M]

Grab a tiny sample in the pippette, invert it and put the bulb in a cup of icewater and jiggle it a bit. Now put it on the prism and read. No need to take the temp, just get it down from boiling.

 

[Spartan1979]

I would think the mass of the refractometer would be enough to get the sample down to ambient temperature.

 

[Revvy]

I would think the mass of the refractometer would be enough to get the sample down to ambient temperature.

Yeah, I mean you have 2 to 3 drops of liquid hitting a glass plate that is going to be ambient temp. Shouldn't that pretty much cool those drops pretty quickly?

 

[mavrick1903]

Yeah, I mean you have 2 to 3 drops of liquid hitting a glass plate that is going to be ambient temp. Shouldn't that pretty much cool those drops pretty quickly?

I agree with this, it's a couple of drops, it dropped lots of heat from when you took the sample, and yet more when you go .... drip.... drip.... drip. JMHO

 

[rcrabb22]

I agree with this, it's a couple of drops, it dropped lots of heat from when you took the sample, and yet more when you go .... drip.... drip.... drip. JMHO

+1

I worry more about the temperature of the refractometer itself. Remember ATC corrects for the temperature of the device not the sample.

I brew in the garage.

In the summer my garage is usually 90F+ on a sunny day and in the winter hovers around +10F of temperature outside. The manual says the refractometer can correct for temperatures in the ranges of 10C - 30C or 50F to 86F. If the ambient temperature of my garage is outside of that range and I can't leave the device out in the garage for any length of time without reducing the accuracy of the measurement. I leave my refractometer in the mudroom just inside from the garage and retrieve it when I want to use it.

 

[ave8tor]

I recently just bought the same refractometer from AHS, and have noticed a disparity between my refractometer and hydrometer. After adjusting the hydrometer reading for the temperature, the corrected specific gravity is approx .006~.008 points above the refractometer's corrected specific gravity. I recently made a red ale and wort hydrometer reading came in at 1.054 (corrected) while the refractometer read 12 Brix (1.047 corrected). This disparity was pretty consistent with fermented beer as well. I also just kegged a cider and the FG hydrometer and refractometer readings were 1.006/.997 (corrected) respectively. This red ale being my first complete batch with the refractometer, I haven't had a complete start to finish reading to compare against. I'd imagine the ABV will be the same regardless if I use the hydrometer or refractometer. I was just curious as to which tool was the more accurate one to use (for my brewing profile and expected gravities). Also, I did calibrate the refractometer, so that can be ruled out.

 

[Yooper]

I recently just bought the same refractometer from AHS, and have noticed a disparity between my refractometer and hydrometer. After adjusting the hydrometer reading for the temperature, the corrected specific gravity is approx .006~.008 points above the refractometer's corrected specific gravity. I recently made a red ale and wort hydrometer reading came in at 1.054 (corrected) while the refractometer read 12 Brix (1.047 corrected). This disparity was pretty consistent with fermented beer as well. I also just kegged a cider and the FG hydrometer and refractometer readings were 1.006/.997 (corrected) respectively. This red ale being my first complete batch with the refractometer, I haven't had a complete start to finish reading to compare against. I'd imagine the ABV will be the same regardless if I use the hydrometer or refractometer. I was just curious as to which tool was the more accurate one to use (for my brewing profile and expected gravities). Also, I did calibrate the refractometer, so that can be ruled out.

Once fermentation begins, and alcohol is in the beer, the readings from the refractometer are not accurate as alcohol skews the way light refracts (what the refractometer reads).

If your hydrometer reads 1.000 in distilled water, and the refractometer reads 0 in distilled water, all that is left to do is to calibrate them to each other. That is called the "wort correction factor". http://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/ is a quick and easy read on how to do that.

Then, you should match every time with wort. Not with beer, of course, as that is a different correction formula.