Refractometer!!

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stephelton

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Picked up a refractometer on a bit of a whim at the LHBS today. I'm pretty excited.

I've got some questions, though for those who have used these before. First off, I'm worried about temperature. I'm sure a droplet of water cools very rapidly, but what is the safe temperature range for these things? The one-page manual didn't mention anything.

What the manual did mention was that I should not use water to clean it, and then it went on to warn about scratching the lense. What's the proper way to clean these?
 
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stephelton

stephelton

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i use a paper towel to wipe mine down.

also, 60* is the correct temperature, as far as i know. I am assuming yours doesn't have the auto-temp correction then.
mine is auto correcting. but i'm afraid that boiling water, for example, might break it. that's probably a little ridiculous, though, since a drop of water would cool very quickly.
 

denimglen

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I just take a sample from the boil/mash with a spoon and drop it on the lens, haven't had any dramas so far.

I think the water warnings are usually about the casing and/or submerging the whole thing.

I just use a wet sponge, rag, paper towel, whatever's handy then just dry it off with my t-shirt haha. Sometimes I'll lick the lens though...who says you can't taste a refrac sample?
 

DeathBrewer

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I've got misreadings from it being too hot on my temp-correcting refract. Just set it down and let it cool for a second if you take it from boiling wort. I think it only needs to get under 90°F or something, and it cools really quickly being exposed to the air in such a thin layer. They work great. I bought mine on a whim, too. Congrats.
:mug:
 

DBbrewing

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I just take a sample from the boil/mash with a spoon and drop it on the lens, haven't had any dramas so far.

I think the water warnings are usually about the casing and/or submerging the whole thing.

I just use a wet sponge, rag, paper towel, whatever's handy then just dry it off with my t-shirt haha. Sometimes I'll lick the lens though...who says you can't taste a refrac sample?
I do the same thing except for licking the lens.:drunk: LOL
 

PseudoChef

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I believe the standard refractometer working range is 60°-85°F. This means both the sample and the refractomter itself must be in this range. During insanely cold or insanely hot brewdays, it's best to keep the refract inside and take your readings there. For example, if the refractometer is sitting ambient at 40° or something, it's going to misread.

But it's such a useful tool - I had a small grain bill yesterday, so I way overshoot my gravity by almost 15 points. Refract allowed me to dilute the wort preboil and adjust hops without waiting for a hydro sample to cool. Was super nice.
 

HairyDogBrewing

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I use an eyedropper to collect samples.
If its really hot, I'll put the sample on a spoon or a plate for a few seconds to cool.

A transfer pipette can reach into fermenters and flasks to check progress.

MoreBeer has a spreadsheet to correct for the alcohol in fermenting beer.
MoreBeer!™: Using a refractometer in brewing | MoreBeer

So, I'm having fun with my refract, but you can certainly make beer without one.:mug:
 
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stephelton

stephelton

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Wtf.

I kegged a beer today and used my refractometer to try to calculate the FG. Based on my OG of 1.044, ProMash told me that I should have 1.0082 or so beer based on a Brix of 4.7 (or something like that.) That would leave me with a ridiculous attenuation, so I decided to try out the method of determining ABV & OG using both a hydrometer and refractometer reading.

My hydrometer sample was about 1.010 after temp adjustment. I decided to tripple (or quadruple) check my refractometer calibration -- and it's definitely spot on (calibrated at about 69 degrees., and I'm using some Ozarka distilled water, ensuring there are no bubbles, etc...)

So I start to wonder about my hydrometer. I happen to have two, so I compare their readings. Indeed, they were noticeably off, but not by much (my beer sample read 1.011 vs 1.010, give or take human error.) A sample taken using distilled water seemed pretty close (right at 1.00).

It's also quite likely that my $15 walmart thermometer is misleading me as well.

I took some New Belgium Abbey Ale, which claims to be 7% ABV as a test. My refractometer reading is 6.7, and my SG reading is 1.013. Plugging these values into ProMash, I'm told that would give me an OG of 1.04858 and ABV of 4.67%. The SG looks appropriate to me, so I'm guessing I've got issues with my refractometer.

Anyone else have any thoughts?
 

flyangler18

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Read this: Refractometer - Home Brewing Wiki

1) A refractometer cannot be used post-fermentation without a correction factor. Alcohol in the sample skews the reading. If you know your OG and input that into the correction calculator, post-fermentation refractometer readings are accurate.

2) You must also compensate for the composition of wort which isn't just water and sucrose.

Something is screwy with that calculation in Promash; Brix x 4 = OG, within a normal margin of error. So, 4.7 x 4 = approximately 1.018.
 
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stephelton

stephelton

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Read this: Refractometer - Home Brewing Wiki

1) A refractometer cannot be used post-fermentation without a correction factor. Alcohol in the sample skews the reading. If you know your OG and input that into the correction calculator, post-fermentation refractometer readings are accurate.

2) You must also compensate for the composition of wort which isn't just water and sucrose.

Something is screwy with that calculation in Promash; Brix x 4 = OG, within a normal margin of error. So, 4.7 x 4 = approximately 1.018.
From what I've read, that calculation is only approximate for pre-fermentation wort. Is it still approximate for post-fermentation? My beer is definitely not 1.018 at this point...

Here's a good read I found: Brew Your Own: The How-To Homebrew Beer Magazine - Projects and Equipment - Refractometers
 
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