The Great Bottle Opener Giveaway

Home Brew Forums > Home Brewing Beer > Equipment/Sanitation > Refractometer Help....?

Reply
 
LinkBack Thread Tools
Old 03-01-2009, 05:51 PM   #1
HOP-HEAD
Feedback Score: 0 reviews
Recipes 
 
Join Date: Oct 2008
Location: West Michigan
Posts: 519
Liked 9 Times on 8 Posts

Default Refractometer Help....?

I purchased a refractometer a few weeks back and am just trying to corolate it to my hydrometer. Unfortunately, I can't figure the darn thing out.

The OG on my English Bitter read just shy of 13 brix, or about 1.052, with the refractometer, which I considered to be reasonably close to my hydrometer reading of 1.050.

However, the OG reading of my Imperial Stout was way different. OG of 1.086 with the hydrometer, and about 10 brix, or 1.040 with the refractometer. This considering a target of 1.090.

When I racked the Imperial to secondary a few minutes ago, the reading was 1.018 with the hydrometer, but still 10 brix, or 1.040 with the refractometer.

Clearly the refractometer isn't reading the Imperial correctly, but why?

__________________
HOP-HEAD is offline
 
Reply With Quote Quick reply to this message
Old 03-01-2009, 06:01 PM   #2
ArcaneXor
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2007
Posts: 4,322
Liked 68 Times on 66 Posts
Likes Given: 10

Default

Three things are going on:

1.) Refractometer readings are not accurate during and post-fermentation, because the ethanol changes the way light is refracted. There is software available that will correct for this discrepancy (e.g. Beersmith), although these conversions aren't 100% accurate - but you can get pretty close.

2.) Refractometers are very sensitive to air bubbles and solids (e.g. tiny hop particles) in the sample. Try to get as clean a sample as possible for your readings.

3.) To get the most accuracy for OG readings, you also need to correct the OG by what's called the wort correction factor. The fact that wort is not a pure sugar solution skews readings slightly. A common correction factor is 1.04. I have found that for my equipment/beers it's closer to 1.02. The MoreBeer spreadsheet assumes it's around 1.07.

I hope this helps!

__________________
The Fiesty(sic) Goat Brewery est. 2007 & Clusterfuggle Experimental Ales est. 2009
Planned: Dark Mild w/ 002, Dark Mild w/ 028, sLambic II, Flanders Red II
Primary: Fat Man Porter w/ 1469, Fat Man Porter w/ 005, sLambic I
Secondary: Orange Blossom Mead, Flanders Red I
Kegged: Centennial Falcon w/ Conan, Centennial Falcon w/ Denny's, Barrel-aged Fat Man Porter, Belgian Dark Strong, Huell Melon Pale Ale
Bottled: Flanders Red I
ArcaneXor is offline
 
Reply With Quote Quick reply to this message
Old 03-01-2009, 06:17 PM   #3
tokolosh
Feedback Score: 0 reviews
Recipes 
 
Join Date: Oct 2008
Location: Portland, OR
Posts: 95
Default

Quote:
Originally Posted by ArcaneXor View Post
3.) To get the most accuracy for OG readings, you also need to correct the OG by what's called the wort correction factor. The fact that wort is not a pure sugar solution skews readings slightly. A common correction factor is 1.04. I have found that for my equipment/beers it's closer to 1.02. The MoreBeer spreadsheet assumes it's around 1.07.
So you're saying add .04 (or whatever your personal adjustment may be) to the brix calculation read as OG. i.e. after figuring out the brix to OG calculation I'm at 1.050. You're saying that my actual reading is 1.054, right?

I hope that made sense...
__________________
"A single fact can spoil a good argument." - Anonymous
tokolosh is offline
 
Reply With Quote Quick reply to this message
Old 03-02-2009, 01:20 AM   #4
ArcaneXor
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2007
Posts: 4,322
Liked 68 Times on 66 Posts
Likes Given: 10

Default

I think the wort correction factor is multiplied, not added, but I don't know the precise formula since I use software for those calculations. There are some online calculators that will do the trick though.

__________________
The Fiesty(sic) Goat Brewery est. 2007 & Clusterfuggle Experimental Ales est. 2009
Planned: Dark Mild w/ 002, Dark Mild w/ 028, sLambic II, Flanders Red II
Primary: Fat Man Porter w/ 1469, Fat Man Porter w/ 005, sLambic I
Secondary: Orange Blossom Mead, Flanders Red I
Kegged: Centennial Falcon w/ Conan, Centennial Falcon w/ Denny's, Barrel-aged Fat Man Porter, Belgian Dark Strong, Huell Melon Pale Ale
Bottled: Flanders Red I
ArcaneXor is offline
 
Reply With Quote Quick reply to this message
Old 03-02-2009, 03:52 AM   #5
Got Trub?
Feedback Score: 0 reviews
Recipes 
 
Join Date: Apr 2007
Location: Washington State
Posts: 1,538
Liked 7 Times on 5 Posts

Default

Here is an article that explains it all: Brew Your Own: The How-To Homebrew Beer Magazine - Projects and Equipment - Refractometers

GT

__________________
Got Trub? is offline
 
Reply With Quote Quick reply to this message
Reply


Quick Reply
Message:
Options
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Refractometer, which is best? Jumbo82 Equipment/Sanitation 10 07-02-2009 11:52 PM
Refractometer FG avaserfi Equipment/Sanitation 6 04-13-2009 05:18 PM
I tried a refractometer- not so hot Hammer General Beer Discussion 32 10-28-2008 02:42 PM
Refractometer akamatt Equipment/Sanitation 15 08-08-2008 08:51 PM
refractometer ROAD MUTANT Equipment/Sanitation 20 06-21-2006 05:16 AM