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Old 10-04-2012, 05:41 PM   #1
nman13
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So i realized what the problem was regarding my "stuck" fermentation. After reading up, i realized that you cant really rely on a refractometer to get brix after the wine begins fermenting as alcohol will distort the reading. I found this conversion sheet online (link below) and when i put in my data i get a reading of negative brix. Does this make sense? can my wine have negative brix or does that just mean it has hit 0 and there is no sugar left? Thank you for your help.


http://morewinemaking.com/content/winemanuals scroll down to where it says "MoreWine! Refractometer Spreadsheet"


PS. i put this on the beer forum because i figured as it is a question about a refractometer it is not exclusive to wine but beer brewers would know the answer as well.

 
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Old 10-04-2012, 06:14 PM   #2
FuzzeWuzze
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Quote:
Originally Posted by nman13 View Post
So i realized what the problem was regarding my "stuck" fermentation. After reading up, i realized that you cant really rely on a refractometer to get brix after the wine begins fermenting as alcohol will distort the reading. I found this conversion sheet online (link below) and when i put in my data i get a reading of negative brix. Does this make sense? can my wine have negative brix or does that just mean it has hit 0 and there is no sugar left? Thank you for your help.


http://morewinemaking.com/content/winemanuals scroll down to where it says "MoreWine! Refractometer Spreadsheet"


PS. i put this on the beer forum because i figured as it is a question about a refractometer it is not exclusive to wine but beer brewers would know the answer as well.
Its negative because you are now below 1.000 SG, which makes sense making wines because you are going to have a very high ABV (relative to beer)

1.000 is the SG of water, which means your liquid is less dense than water, because of its high alcohol content(alcohol is less dense than H2O)

 
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Old 10-04-2012, 09:58 PM   #3
ajf
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You are right that the alcohol will affect the Brix reading, but I'm pretty sure that you cannot get a negative reading.
I didn't check the linked spread sheet, but I did take a Brix reading of a Bordeaux that I will shortly drink with my dinner. It read 7*Brix.
I also know that the calculators that I have used used for beer are not very accurate when forecasting the F.G.

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Old 10-04-2012, 10:01 PM   #4
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As far as I know the alcohol compensation is for measuring finished gravity. Sugar content is read directly,

 
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Old 10-05-2012, 02:06 PM   #5
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Thinking about it, it is impossible to get a negative Brix.
It means that the calculator is not completely accurate as the Brix value will reduce to 0 when there is no more sugar, and cannot reduce any further.

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Old 10-05-2012, 02:21 PM   #6
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Correct. You cannot have negative Brix because it is a measure of sugar in water. Negative Brix would mean you had a situation where there was less than zero sugar in the solution (ie. you could add some sugar and still have none). Impossible.

However, since you determine Brix based on a hydrometer reading, it is possible to have a negative reading. This just means that there is enough alcohol (or anything else) to make the density of water less than 1.000.

As the last poster said, a correction is needed to fix that.

Strictly speaking, you cannot take a direct measurement of Brix in a solution containing anything BUT sucrose and water. Anything else (including the other constituents of wart) will require some correction factor, although many are likely so insignificant that the correction is not needed to be reasonably accurate. Alcohol content does require a correction, though.

 
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Old 10-05-2012, 02:37 PM   #7
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Final gravity brix conversion is unreliable. Use a hydrometer.
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