Hydrometer vs Refractometer

[mrbobble]

Are the majority of you using the ATC enabled refractometers that measure in gravity as well? Does anyone have any positive experience with refractometers? Usually no news is good news so there's got to be someone who isn't speaking up that's had good results with them...hopefully.
(I'm tired of breaking hydrometers. I break them about once a year/every six months)

 

[rycov]

Oops.... I've been out of pocket lately and didn't see this response. I'll probably just hang on to it, why I'm not sure. I definitely would not buy one again however.

Sorry about the tease....

its cool. i actually ended up buying on. just got it last weekend and haven't used it yet though. i calibrated it in water (actually i just checked it and it was already correct). its the one with ATC and it reads in brix and SG. i'll use it along with the hydrometer for the next few batches and see if i'm ok with the inconsistency/ can figure out a correction factor for it. i'll let you guys know what i find works for me

 

[Boru]

I have a friend that uses one which is in Brix, not SG. He's actually had fairly good success with it and by and large. He does have a fancy hydrometer that he used to calibrate it first and still occasionally does calibrate it but he by and large uses it with a fair amount of accuracy to check the FG readings. He enjoys not having to waste a half a beer.

I do have plans to get one some day so I'm curious as to what models people have had good experiences with, largely because a couple times I've forgotten to pour off a FG sample and it would be nice to be able to think, oh I'll just pull out the eyedropper and grab a bit off the top right now.

 

[rycov]

any idea how he calibrates it?

 

[DakotaRules]

To calibrate a brix meter or refractometer you use distilled water and zero out the meter.

 

[rycov]

oh. i meant for his beer. i was reading where others were saying you had to come up with a correction number to get an accurate reading for wort and a different calculation for fermenting or fermented beer

 

[ArcaneXor]

I have a refractometer that I originally got as a hydrometer replacement, but quickly realized that it doesn't work all that well for that purpose, since the ethanol correction formulas and spreadsheets are fairly useless. Someone just recently developed a set of formulas that are supposedly more accurate, but I haven't played with them yet. The link for the new formulas is http://seanterrill.com/2011/04/07/refractometer-fg-results/

A couple of things to note:

Refractometers with a SG scale still need to be corrected by the wort correction factor. Also, Gordon Strong reports that some of them are incorrectly scaled (i.e. the scale is SG=4 Brix, which isn't quite correct).

Refractometers are very useful when quick measurements of hot liquids are required, such as figuring out when the SG of the second or third runnings are starting to run too low, or for a pre-boil gravity reading to verify that starch conversion occurred properly.

Salt water refractometers are useless for brewing. You need a sugar hydro.

Immersing the refractometer into hot liquids can screw up the ATC. Take a sample and drip it onto the refractometer slide, then close it to take the reading.

Make sure that your sample doesn't have any air bubbles or protein/hop particles in it. That can skew the reading quite a bit.

Stir the liquid you are testing to make sure it is well-mixed. Since the sample size is so small, sampling bias is a much bigger problem than with a hydrometer.

Repeat each measurement twice to make sure you get a consistent reading.

 

[rycov]

good info. thanks for the link!

 

[wildwest450]

I'm going to use mine for the first time on Friday. I got the one with a brix and sg scale. It was spot on with distilled water calibration, and it was sopt on with my starter wort 1.036, checked with 3 hydrometers. Fwiw, they are designed to only measure sugar content, not alcohol, I knew this going in. Just hope it's easier than cooling 3-4 wort samples throughout the brew day.

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[Bobby_M]

Another thing to note here. ATC is meant to correct for varying ambient temps but NOT varying sample temps. The sample has to be the same temp as ambient for it to read accurately immediately, otherwise you have to give the prism/body some time to pull the heat out of the sample. The one issue you have if you let it sit for too long is that some of the water can evaporate out of the sample creating an artificially high reading.

Here's what I do. When I pull a sample into the pipette, I make sure it's a very small amount. Then I shake it bulb side down in a cup of icewater for 5 seconds before dropping the sample on the plate. Now it's closer to ambient temps and will be more accurate.

 

[rycov]

it only takes a drop or two. how long would that take to cool off? it seems like putting it in ice water would make it too cold?

 

[wildwest450]

Ok, I brewed yesterday and used the new refractometer. I cooled all samples to 68f as I was checking everything against the hydrometer anyways. My preboil was 1.035 with the refractometer, and 1.036 with the hydro. Finished wort was 1.046 with the refractometer and 1.047 with 3 different hydrometers. I did get some wacky readings if I didn't chill the samples, I guess the only advantage is you don't have to draw a large sample to chill, I just put an ounce in a plastic shot glass and put that in a glass of ice water.


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[Bobby_M]

Not even a shot glass. Like I was saying, the tiny ml in the pipette cools off really quickly in a ice bath.

 

[wildwest450]

Not even a shot glass. Like I was saying, the tiny ml in the pipette cools off really quickly in a ice bath.

But how do you know when it's "cool enough". I did try that and it gave me some strange readings.

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