pint of lager
brewing on the verandah
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To understand the readings of feremnting wort, you must get a grasp of real and apparent attenuation.
Real attenuation is the actual amount of malt sugars remaining, as shown by the refractomter.
Apparent attenuation is the amount shown by the hydrometer, which is actually an incorrect reading.
Before pitching the yeast, the wort is a mixture of malt sugars and water. After fermentation starts, there is less sugars and more alcohol. Alcohol is less dense than water, and the hydrometer is a poor tool for measuring two fluids with different densities, and sugar. The less dense alcohol causes the hydrometer to float lower in the fermenting wort.
If you took a 200ml sample of fermenting wort, remove the alcohol by boiling, then add water to bring the volume back to 200ml, then floated your hydrometer in this sample, the hydrometer would show a much larger reading, and give the real attenuation.
So make sure you use your favourite brewing software to track the refractometer reading of the ferementing wort and give you apparent antenuation like you are used to with the hydrometer.
For the first few brews, I suggest you do a hydrometer reading and refractometer reading at the same time, to give you a good understanding of what is happening.
Using a refractometer really makes you pay attention to the residual sweetness that must be balanced by the correct amount of hops.
Real attenuation is the actual amount of malt sugars remaining, as shown by the refractomter.
Apparent attenuation is the amount shown by the hydrometer, which is actually an incorrect reading.
Before pitching the yeast, the wort is a mixture of malt sugars and water. After fermentation starts, there is less sugars and more alcohol. Alcohol is less dense than water, and the hydrometer is a poor tool for measuring two fluids with different densities, and sugar. The less dense alcohol causes the hydrometer to float lower in the fermenting wort.
If you took a 200ml sample of fermenting wort, remove the alcohol by boiling, then add water to bring the volume back to 200ml, then floated your hydrometer in this sample, the hydrometer would show a much larger reading, and give the real attenuation.
So make sure you use your favourite brewing software to track the refractometer reading of the ferementing wort and give you apparent antenuation like you are used to with the hydrometer.
For the first few brews, I suggest you do a hydrometer reading and refractometer reading at the same time, to give you a good understanding of what is happening.
Using a refractometer really makes you pay attention to the residual sweetness that must be balanced by the correct amount of hops.