Refractometer Question

[TheMattTrain]

I got myself a refractometer on Black Friday off Amazon for super cheap. I planned on taking a reading of my IIPA using both my refractometer and hydrometer to compare the samples, but I broke my hydrometer while setting up to siphon (whoops).

Anyway, I took the sample using my new refractometer and it measured 1.030 instead of the 1.010 I expected. I read later that alcohol can distort the reading on a refractometer.

Is it general practice to use a hydrometer after fermentation has begun or do you use a refractometer and do some type of conversion?

Thanks for your help!

 

[KartRacer54]

Seems I have seen that most people use refracts re for wort and hydrometer for beer. I have also found that there are several conversion tools available to use refractometer for beer. That is my choice because I hate wasting beer on the hydrometer. I have not had the opportunity yet though. BTW I also broke my hydrometer day before needing it.

 

[FarmerTed]

If you have brewsmith, use the refractometer tool to get at your finishing gravity. You need to input the O.G. and then the brix reading of the finished/fermenting beer. It's quite accurate. There are online calculators as well. If I input 1.070 g/ml (as an OG guess) and 7.5 brix, I get an FG of 1.005 and 8.6% abv (seems low on the FG).

 

[Yooper]

Some of the refractometer calculators for post-fermentation readings are considered to be ok- sean terrill's for one. But I've never had one be accurate, so I use my refractometer preboil and post boil and hydrometer post fermentation.

This is true for my wines, also- I use a hydrometer in winemaking except when I check fruit for brix. (I've been making wine a heck of a lot longer than brewing, and consider myself a winemaker first).

 

[kh54s10]

Some of the refractometer calculators for post-fermentation readings are considered to be ok- sean terrill's for one. But I've never had one be accurate, so I use my refractometer preboil and post boil and hydrometer post fermentation.

This is true for my wines, also- I use a hydrometer in winemaking except when I check fruit for brix. (I've been making wine a heck of a lot longer than brewing, and consider myself a winemaker first).

In the three + years I have been here I have found that you are a great source of info on wines...

You are also a great source of info on beer.

I would classify you as a Brewmaster/Sommelier.

 

[Yooper]

In the three + years I have been here I have found that you are a great source of info on wines...

You are also a great source of info on beer.

I would classify you as a Brewmaster/Sommelier.

Thank you for the kindness. I appreciate it!

But I'm pretty much just a winemaker/brewer.

 

[soccerdad]

I'm one of those who refracts on brew day (until yeast goes in) - and then I hydro. Otherwise there is math involved ... no math for this guy.

 

[b-boy]

I use a refractometer full time. I use the calculator in BeerSmith to do the conversions. The readings are close enough for my needs.

 

[raysmithtx]

Yep me too. I use a refractometer exclusively. I checked several batches comparing my hydrometer with the adjusted refractometer in Beersmith. The FG readings were/are extremely close.

I like only using a few drops to get my SG readings.

 

[Calder]

Many people are comfortable using refractometers for all readings. I am not one of them.

When deciding to use a refractometer, remember it is not as accurate as an hydrometer.

A refractometer measures simple sugars. Even the OG measurement of wort with a refrac is an estimate. You convert the BRIX to SG and then add 1 or 2 percent. If it is a highly fermentable wort, like a Belgian with lots of sugar you will be over estimating the gravity. If it is a thick Stout or BW with lots of complex sugars you will be underestimating the gravity. Not by much, but it is an inaccuracy in the measurement/estimation.

Once you have alcohol, you need to use a calculator to convert the reading to gravity. For average beers, with average attenuation, they are pretty good. The calculators are nothing more than a data set of fermentation results and use the average of the results for the conversion. Due to differences in complex sugars in worts/beers, you may or may not have a wort that conforms to the average. There is no science in the conversion, just math based on a data set. If your wort is a low OG, or high OG, you will get greater inaccuracy since the conversion is based on 'normal' beers. ........ And the FG is also based on the OG you measured, so any inaccuracy in that measurement is only compounded in the conversion.

My advice to anyone using a refractometer, is to take both a refrac and hydro measurement for several beers and different types and gravities, to understand how accurate the instrument is.

 

[Trollheim]

Hey,

I use a refractometer exclusively now as well. When I first decided to take the plunge I used both and compared the calculations over time, very accurate.

I will note that you HAVE to have taken your OG reading for the calculation.

I first saw this in a video from BobbyG/BobbyFromNJ in his comparison video.

http://youtu.be/KaonMYRODks

Part way through the video he links to the following tool I first used.

http://morebeer.com/public/beer/refractbeer.xls

I have since moved over to putting the numbers in Beersmith.

Cheers,

Scott

 

[TheMattTrain]

Thanks for your responses, everyone. I LOVE these boards because of how helpful everyone is. I swear, Yooper might be my guardian Brewangle. I feel like she responds to every thread I post.

Trollheim - That spreadsheet is exactly the type of thing I was looking for. I'm glad to know my FG isn't actually 1.030. What a sweet IIPA that would be! I'm glad it's more like a 1.010-1.005 FG so my ABV is around 8.5. I can't wait for that beer to finish carbing... Hopefully tomorrow after work.

Thanks again homebrewtalkers! You all rock!

 

[b-boy]

Many people are comfortable using refractometers for all readings. I am not one of them.

When deciding to use a refractometer, remember it is not as accurate as an hydrometer.

I hear this all the time, but to be honest with you there are a lot of variables that need to be in place to get a good reading off of a hydrometer. Temperature, dissolved CO2, the quality of the instrument, and reading the device properly also add a little error into the equation. Let's be honest, a $3 hydrometer and/or a $20 refractometer will only be so accurate.

I'm convinced that a professional using a hydrometer probably gets a more accurate reading every time.
-However -
A half-buzzed homebrewer in his garage probably doesn't. Why do you think so many hydrometers get broken?

I'd probably make the same argument for the refractometer as well.

For that reason I'm OK with a refractometer. I think the margin of user error involved in taking a hydrometer reading generally negates any perceived accuracy gains. If I was a professional brewer, that answer might be different.

Just my opinion - speaking out as a half-buzzed homerbrewer.

Of course YMMV.