7bruno7 wrote: ↑Tue Aug 16, 2022 11:07 am
I checked the fermenter earlier this morning with the digital refractometer, like the one in the pic below, and the gravity was still 1.025, but when I checked the gravity with the glass hydrometer, the gravity was only 1.008. So, apparently my digital refractometer may not be correct, even though it was calibrated to 1.00 with water. Has anyone else experienced the cheapo digital refractometers from Amazon being super inaccurate??
I think what you have pictured there is an (analog) optical refractometer - not a digital one.
My refractometer (looks like yours) arrived in the mail the day before yesterday. Yesterday afternoon I tried to read the ABV of a commercial beer that was labeled as 5.5%. My (freshly calibrated) refractometer gave me a weak 3.3% measurement instead.
I spent most of this morning reading about refractometers. My optical instrument has a Brix scale and an
ABV scale (labeled “Approximate Value Degree Alcohol”). Other similar looking refractometers might have a Brix and a
specific gravity scale, instead.
Over and over it was repeated in various other forums, that SG and ABV scales in such instruments are crap (for SG readings / not Brix). The instrument does not read density (specific gravity). These scales are estimations and are notoriously inaccurate. Don't use them. Use only the Brix scale. And then later rely upon a hydrometer, not the refractometer, once fermentation has begun.
Conclusion: Refractometers are really useful for reading sugar levels in something like a ripe grape. But not once fermentation begins and alcohol begins to replace sugar.
Pure water = 0 deg Brix
25 deg Brix = 25 grams sugar / 100 grams water
The target range for harvesting white grapes is between 19 – 25 deg Brix (11 - 13.3% ABV)
The target range for harvesting red grapes is between 22 – 26 deg Brix (12 -14.3% ABV)
A Brix reading can be multiplied by 0.55, to roughly estimate the ABV of a dry wine.
< for the OP of this thread>
Your not making wine, but look down at the bottom half of
this page, to notice what is said about temperature shifts, rehydration of dry yeast in water (not must or wort) and stirring in more oxygen.