Refractometer and Hydrometer Scales

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Keith66

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I'm looking at buying a refractometer for brewing my beer. In doing so I've learned a little about SG and brix scales, and the calculation between the two. I've also seen many people comment that the SG scale in refractometers is correct only at 1.000, with an increasing error relative to three brix scale. This is supported by the calculation. I've heard it explained that refractometers were designed for brix, then the SG scale was added, but not accurately. And every dual scale refractometer has the same scale, which makes me suspect that maybe there is some validity to it. So tonight I played with the Brewer's Friend calculator, compared it to my hydrometer, and found that not only do the refractometer scales appear to not match up, but my hydrometer scales don't match up either. So now I'm not sure what to believe. My beer turns out pretty good and gets me looped, so this is all semantics of course, but I'm curious to hear what others think or know about this. Thanks in advance!
 
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Keith66

Keith66

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That's the direction I'm heading. I was surprised to see that the scales didn't match up on my hydrometer. I'm tempted to get a brix refractometer and use the equations for SG and FG.
 

duboman

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Calibration is the key and also keep in mind that in the presence of alcohol, refractometers require calculations to read properly and IME can still be off.

Your hydrometer should read 1.000 in distilled water at its calibration temp printed on the label/insert, mine is 68oF. I don't use a refractometer for anything other than a simple, quick reading from the mash and pre-boil.
 

phug

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Now I have to go look at my hydrometer


Sent from my iPhone using Home Brew
 
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Keith66

Keith66

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I found the discrepancy. There are 3 ways to convert from brix to SG. There's the Kaminski BYO conversion, the Bruce's Blog conversion, and "multiply by 4". Refractometers use the Kaminski conversion accurately lined up next to the brix scale, and Brewer's Friend uses a conversion very similar to Bruce's Blog. That's why calculations come out different than the refractometer scales. And "multiply by 4" gets you in the ballpark. All of these are close enough for my brewing. Also, hydrometers read actual SG, whereas refractometers read light through sugar water, which is similar to wort but not exactly the same, and then approximate SG. I also learned that I don't really need a refractometer (after all this!). Since I BIAB, I'm not taking a bunch of gravity readings before and during the boil. I just brew, cool, top off to 5.25 gallons, check OG and pitch. I check OG to see where I got, not as a target. Fortunately I'm usually dead on or very close. One or two FG readings and I'm done. My hydrometer works fine for that. So this is all fine and great, and answered my question, but it's kinda mind-numbing too. Time for a brew.
 
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Keith66

Keith66

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Found this online.

1415683243889.jpg
 
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