Author Topic: Refractometer tool - calibration and purpose  (Read 9457 times)

Offline pretzelb

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Refractometer tool - calibration and purpose
« on: February 02, 2010, 06:43:12 AM »
My first question is what should you do for calibration if you don't have a hydrometer that you can rely on? Part of the reason I got a refractometer was because I didn't think my hydrometer was accurate and I was very frustrated in trying to test it with 60 degree water (too warm, no too cold, no too warm again). So if your hydrometer isn't accurate or you don't have one, what should you do?

More importantly I'm not sure I understand the purpose of this tool. I have readings for pre fermentation and pre bottle but I'm not seeing what I expect. If I select "unfermented" and enter my value I get a SG that I think is correct. I then switch to "finished" and try to enter that value but the results are very strange. Clearly I'm not using this as expected but I can't figure out what you're supposed to do. I just want to use my brix settings to find the translated gravity readings and ABV.

Offline BeerSmith

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Re: Refractometer tool - calibration and purpose
« Reply #1 on: February 02, 2010, 07:21:27 AM »
Hi,
  I am working on a video for this as I get frequent questions on this.  The calibration is necessary because refractometers are basically calibrated to sucrose and not maltose, which is why you need the tool in the first place.  The brix readings you get off a refractometer are not calibrated to malt.

Frankly a good quality hydrometer (which is what I use) is probably a more practical tool for the average homebrewer than a refractometer.

To determine OG for your wort, use the unfermented wort setting and simply enter the reading (once you have calibrated).  This will give you your OG.  For partially or fully fermented beer, use the "fermenting wort" setting, and enter both your refractometer reading and also your OG which hopefully you took up front.

Finally, the finished beer setting is really used to back out your OG if you missed it up front.  You can enter both the refractometer reading and a simultaneous hydrometer reading for the finished beer, and the tool will back calculate your OG.

Cheers,
Brad
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Offline MaltLicker

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Re: Refractometer tool - calibration and purpose
« Reply #2 on: February 02, 2010, 10:00:58 AM »
Frankly a good quality hydrometer (which is what I use) is probably a more practical tool for the average homebrewer than a refractometer.

Brad reminds us that refracts are made for sucrose, so his BSmith tools are necessary for our hobby.  But I LOVE my refract.  I too had a lousy hydro, and I was brewing small batches inside, so every drop of wort was sacred.  With cooling-down time, 4 oz to fill the hydro tube a few times was costly.  The uses of a refract pre-boil are numerous:  progress of mash, final runnings, pre-boil SG, near-terminal SG (to ensure progress), and final OG upon pitching.  You never have to accept a missed OG b/c you can verify and add/dilute before flame-out.  And each sample is drops worth. 

To calibrate a refract, use distilled water to set Zero, and you can make a sucrose (sugar) water solution at the ol' one pound per gallon ratio or 8 oz water and 1 oz sugar.  You should get 1.046 on the device.  If you do, it works, and you just need BSmith tools to adjust to maltose-relevant readings. 

But as far as brewing tools on brew day, I think refracts are very helpful.  They're on ebay for $38 delivered all the time. 

Offline pretzelb

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Re: Refractometer tool - calibration and purpose
« Reply #3 on: February 02, 2010, 12:11:50 PM »
I admit that I bought my refractometer without doing enough research but it would seem that all the calculations you can do pre-fermentation should be useful. Especially when it comes to working with hot wort. Looking back my money might have been better spent on a hydrometer that has a thermometer built in. But one thing I do hate about hydrometers is the need to use a thief and therefore a high (imo) risk to contamination.

As of right now I am disappointed in BrewSmith's ... shall we say "attitude" ... toward refractometers as indicated by the tool. If I'm understanding everything I see in the tool, a refractometer is totally useless without a hydrometer along side to validate it's readings. I know my knowledge is limited but you would think that if a refractometer is calculated on it's own against distilled water, it should be possible to get a reasonable conversion of brix to gravity.

I did calibrate with distilled water but I didn't try the 8oz water and 1oz sugar test. Let me try that.

Offline Andrewqld

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Re: Refractometer tool - calibration and purpose
« Reply #4 on: February 02, 2010, 02:45:34 PM »
Calibrating the refrac is not that hard and only really needs to be done the once,  I can't see any "attitude" as you were given a reply that answered your question, refractometers are designed for sucrose not maltose and that's not the fault of BeerSmith, however BeerSmith has provided the tools to convert the refrac readings so they are relevant to Maltose, I think that's pretty cool.

I have taken the time to calibrate my refractometer using a hydrometer and now only use my refrac for pre fermentation readings, and there are plenty of those as pointed out by maltlicker.

Andrew

Offline pretzelb

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Re: Refractometer tool - calibration and purpose
« Reply #5 on: February 02, 2010, 04:52:23 PM »
Calibrating the refrac is not that hard and only really needs to be done the once,  I can't see any "attitude" as you were given a reply that answered your question, refractometers are designed for sucrose not maltose and that's not the fault of BeerSmith, however BeerSmith has provided the tools to convert the refrac readings so they are relevant to Maltose, I think that's pretty cool.

I have taken the time to calibrate my refractometer using a hydrometer and now only use my refrac for pre fermentation readings, and there are plenty of those as pointed out by maltlicker.

Andrew


Let me be clear that when I say "attitude" I don't mean that any person has been anything but helpful. I mean the tool itself (not a person) as I understand it, seems to be saying that a refractometer is really only a hydrometer tag along. So I'm saying BeerSmith the software (not any person) is providing this calculator in way that says (to me) "sheesh, you have a refractometer? oh well, I guess I'll try and help you but it's really such a stupid thing to have." Also, I'm certainly not saying that I know better either.

I suppose I'm mostly mad at myself for buying the refractometer. From what I'm reading and what BeerSmith is saying, it would be useless without a hydrometer to validate it. I certainly didn't buy a refractometer to compliment my hydrometer because my hydrometer drove me nuts and didn't give me what I thought were accurate readings. Now I learn the better approach is to get a better hydrometer.

I need to read more about refractometers but I'm just annoyed that I have to calibrate it with a hydrometer. Especially since I'm not so sure about the accuracy of the hydrometer I own (and it's requirement to have 60 degree water for it's own calibration).

In the end I'm mostly ranting for which I apologize.

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Re: Refractometer tool - calibration and purpose
« Reply #6 on: February 02, 2010, 06:58:51 PM »
No problems,
  If you do some research online you will find that the three basic modes in the refractometer calculator are the same ones available if you assemble various formulas online.

  As others have pointed out, after you calibrate your refractometer you really don't need a hydrometer unless you forgot to take your OG reading and want to back it out from the final readings.

  I'm not negative on refractometers - they can be much quicker than hydrometers, and usually do not need the temperature correction when working with hot wort.  Keep in mind I'm a bit old school as well - I started brewing in the 80's!

Cheers,
Brad
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Offline MaltLicker

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Re: Refractometer tool - calibration and purpose
« Reply #7 on: February 02, 2010, 08:23:16 PM »
From what I'm reading and what BeerSmith is saying, it would be useless without a hydrometer to validate it.

I need to read more about refractometers but I'm just annoyed that I have to calibrate it with a hydrometer.

I think there might be a slight misunderstanding as to the types of calibration. 

Out of the box, one may not have to check the refract at all beyond verifying distilled reads Zero.  Then you trust your readings (in sucrose) and use BSmith to adjust to a maltose-based reading if desired.  I don't believe the differences are huge, and for the majority of these pre-boil uses, likely not critical. 

I was curious, and did the sugar water test partially b/c I was equally frustrated with a cheap hydro, and was testing both. 

Somewhere in the midst of this adventure for me, I also bought a quality hydro, but it only reads from 0.0 to 1.070, so no tool is the sole and best answer.  (And now that I brew outside and have excess wort I use the hydro for the final OG reading.)   I imagine you'll find your best uses for both as well.


 

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